Merge ../kassandra

.obelisk/impl/default.nix

@@ -0,0 +1,2 @@
+# DO NOT HAND-EDIT THIS FILE
+import (import ./thunk.nix)

.obelisk/impl/github.json

@@ -0,0 +1,8 @@
+{
+  "owner": "obsidiansystems",
+  "repo": "obelisk",
+  "branch": "release/0.9.0.1",
+  "private": false,
+  "rev": "11beb6e8cd2419b2429925b76a98f24035e40985",
+  "sha256": "0b4m33b7yyzsbkvfz2kwg4v9hlnvbjlmjikbvwd7pg52vy84and0"
+}

.obelisk/impl/thunk.nix

@@ -0,0 +1,9 @@
+# DO NOT HAND-EDIT THIS FILE
+let fetch = { private ? false, fetchSubmodules ? false, owner, repo, rev, sha256, ... }:
+  if !fetchSubmodules && !private then builtins.fetchTarball {
+    url = "https://github.com/${owner}/${repo}/archive/${rev}.tar.gz"; inherit sha256;
+  } else (import <nixpkgs> {}).fetchFromGitHub {
+    inherit owner repo rev sha256 fetchSubmodules private;
+  };
+  json = builtins.fromJSON (builtins.readFile ./github.json);
+in fetch json

apps/kassandra/.gitignore

@@ -0,0 +1,14 @@
+.envrc
+.direnv
+.ghc.environment.x86_64-linux-8.6.5
+dist-newstyle
+dist
+result
+result-*
+result-android
+result-ios
+result-exe
+.attr-cache
+ghcid-output.txt
+profile
+hie-output

apps/kassandra/README.md

@@ -0,0 +1,37 @@
+# kassandra
+
+*Kassandra from Greek mythology tells the Trojan _warriors_ in the Illiad not to take in the horse offer by the Greek. They don‘t listen to her.*
+
+This is a taskwarrior frontend build with Haskell and reflex-frp.
+
+**WARNING: This will eat all of your tasks! This app is underdocumented and not intended for use by anyone else, yet.**
+
+## State
+
+* This project is primarily for my personal use. I share it in the spirit of free software but it is not primarily intendend to be usable for anyone else, at least at the moment.
+* This app provides a GUI to view and edit tasks.
+* You can compile the standalone:kassandra2 target with ghc to get a webkit-gtk-app or you can compile with obelisk to get a webserver. (Which needs some authorization right now.)
+* Right now there are only a few custom lists to see tasks. The most useful one under the button "List" are lists based on any tag.
+* It is supposed to be completely reactive, so everything it shows should be up-to-date. It relies right now on two netcat hooks to get updated from taskwarrior:
+
+```shell
+❯ cat ~/.task/hooks/on-add.kassandra-notification
+#!/bin/bash
+tee > (nc 127.0.0.1 6545)
+❯ cat ~/.task/hooks/on-modify.kassandra-notification
+#!/bin/bash
+tail -n 1 | tee >(nc 127.0.0.1 6545)
+```
+
+(In the future these hooks might be generated by the program.)
+
+* Right now the app shows tasks in a tree. Tasks tagged with +root are roots. Tasks with partof:<uuid-of-parent> are children. If you dont use this feature you can still see a plain list of tasks and edit them.
+* You can sort tasks by dragging and dropping them either in a taglist or as children of a common parent. The sortposition is saved in custom uda attributes.
+
+## Plans
+
+* The default UI should use some reasonable search dialog which should more or less fit normal taskwarrior use.
+* Some calendar integration to sort tasks by time.
+* UI improvements und documentation. The current UI is not self explanatory and has some ugly quirks.
+* Custom UDA based features should be deconfigurable.
+* There is supposed to be a solid auth system so you can use any client: Android/webkit/web to connect to any server.

apps/kassandra/backend/LICENSE

@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU Affero General Public License is a free, copyleft license for
+software and other kinds of works, specifically designed to ensure
+cooperation with the community in the case of network server software.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+our General Public Licenses are intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
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+want it, that you can change the software or use pieces of it in new
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+
+  Developers that use our General Public Licenses protect your rights
+with two steps: (1) assert copyright on the software, and (2) offer
+you this License which gives you legal permission to copy, distribute
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+conveyed by you (or copies made from those copies), or (b) primarily
+for and in connection with specific products or compilations that
+contain the covered work, unless you entered into that arrangement,
+or that patent license was granted, prior to 28 March 2007.
+
+  Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+  12. No Surrender of Others' Freedom.
+
+  If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot convey a
+covered work so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you may
+not convey it at all.  For example, if you agree to terms that obligate you
+to collect a royalty for further conveying from those to whom you convey
+the Program, the only way you could satisfy both those terms and this
+License would be to refrain entirely from conveying the Program.
+
+  13. Remote Network Interaction; Use with the GNU General Public License.
+
+  Notwithstanding any other provision of this License, if you modify the
+Program, your modified version must prominently offer all users
+interacting with it remotely through a computer network (if your version
+supports such interaction) an opportunity to receive the Corresponding
+Source of your version by providing access to the Corresponding Source
+from a network server at no charge, through some standard or customary
+means of facilitating copying of software.  This Corresponding Source
+shall include the Corresponding Source for any work covered by version 3
+of the GNU General Public License that is incorporated pursuant to the
+following paragraph.
+
+  Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
+under version 3 of the GNU General Public License into a single
+combined work, and to convey the resulting work.  The terms of this
+License will continue to apply to the part which is the covered work,
+but the work with which it is combined will remain governed by version
+3 of the GNU General Public License.
+
+  14. Revised Versions of this License.
+
+  The Free Software Foundation may publish revised and/or new versions of
+the GNU Affero General Public License from time to time.  Such new versions
+will be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU Affero General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU Affero General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU Affero General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If your software can interact with users remotely through a computer
+network, you should also make sure that it provides a way for users to
+get its source.  For example, if your program is a web application, its
+interface could display a "Source" link that leads users to an archive
+of the code.  There are many ways you could offer source, and different
+solutions will be better for different programs; see section 13 for the
+specific requirements.
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU AGPL, see
+<https://www.gnu.org/licenses/>.

apps/kassandra/backend/backend.cabal

@@ -0,0 +1,106 @@
+cabal-version:      2.4
+name:               backend
+version:            0.1
+
+-- BEGIN dhall generated common configuration
+license-file:       LICENSE
+author:             Malte Brandy
+maintainer:         malte.brandy@maralorn.de
+build-type:         Simple
+extra-source-files: CHANGELOG.md
+
+common common-config
+  default-extensions:
+    AllowAmbiguousTypes
+    ConstraintKinds
+    DataKinds
+    DeriveAnyClass
+    DeriveGeneric
+    DuplicateRecordFields
+    EmptyCase
+    FlexibleContexts
+    FlexibleInstances
+    GADTs
+    LambdaCase
+    MultiParamTypeClasses
+    NamedFieldPuns
+    OverloadedLabels
+    OverloadedStrings
+    PartialTypeSignatures
+    PatternGuards
+    PatternSynonyms
+    QuasiQuotes
+    RankNTypes
+    RecursiveDo
+    ScopedTypeVariables
+    StandaloneDeriving
+    StrictData
+    TemplateHaskell
+    TupleSections
+    TypeApplications
+    TypeFamilies
+    UndecidableInstances
+    ViewPatterns
+
+  ghc-options:
+    -Weverything -Wno-unsafe -Wno-safe -Wno-all-missed-specialisations
+    -Wno-implicit-prelude -Wno-missed-specialisations
+    -Wno-monomorphism-restriction -Wno-partial-fields
+    -Wno-missing-import-lists -Wno-orphans -Wcompat
+
+  mixins:             base hiding (Prelude)
+  default-language:   Haskell2010
+
+-- END dhall generated common configuration
+
+
+library
+  import:          common-config
+  hs-source-dirs:  src
+
+  if impl(ghcjs -any)
+    buildable: False
+
+  build-depends:
+    , aeson
+    , async
+    , base
+    , containers
+    , dhall
+    , data-default-class
+    , frontend
+    , say
+    , kassandra
+    , network-simple
+    , obelisk-backend
+    , obelisk-route
+    , password         >=2.0.1.0
+    , relude
+    , snap-core
+    , standalone
+    , stm
+    , taskwarrior
+    , uuid
+    , websockets
+    , websockets-snap
+
+  exposed-modules:
+    Backend
+    Backend.Config
+
+executable backend
+  import:         common-config
+  main-is:        main.hs
+  hs-source-dirs: src-bin
+
+  if impl(ghcjs -any)
+    buildable: False
+
+  build-depends:
+    , backend
+    , base
+    , frontend
+    , kassandra
+    , obelisk-backend
+
+  ghc-options:    -threaded

apps/kassandra/backend/frontend.jsexe

@@ -0,0 +1 @@
+../frontend-js/bin/frontend.jsexe

apps/kassandra/backend/frontendJs/frontend.jsexe

@@ -0,0 +1 @@
+../../frontend-js/bin/frontend.jsexe

apps/kassandra/backend/hie.yaml

@@ -0,0 +1,2 @@
+cradle:
+   none:

apps/kassandra/backend/src-bin/main.hs

@@ -0,0 +1,8 @@
+module Main (main) where
+
+import Backend
+import Frontend
+import Obelisk.Backend
+
+main :: IO ()
+main = runBackend backend frontend

apps/kassandra/backend/src/Backend.hs

@@ -0,0 +1,87 @@
+module Backend (
+  backend,
+) where
+
+import Backend.Config (BackendConfig, readConfig, users)
+import Control.Concurrent.STM.TQueue (TQueue, newTQueueIO, writeTQueue)
+import Control.Exception (try)
+import qualified Data.Aeson as Aeson
+import Data.Map (lookup)
+import Data.Password.Argon2
+import Frontend.Route (BackendRoute (..), FrontendRoute, fullRouteEncoder)
+import Kassandra.Config (AccountConfig (..))
+import Kassandra.LocalBackend (LocalBackendRequest (..))
+import Kassandra.Standalone.State (localBackendProvider)
+import Network.WebSockets (ConnectionException, ServerApp, acceptRequest, forkPingThread, receiveData, rejectRequest, sendTextData)
+import Network.WebSockets.Snap (runWebSocketsSnap)
+import Obelisk.Backend (Backend (..))
+import Obelisk.Route (R, pattern (:/))
+import Say (say)
+import Snap.Core (MonadSnap, Snap)
+
+backend :: Backend BackendRoute FrontendRoute
+backend =
+  Backend
+    { _backend_run = serveSnaplet
+    , _backend_routeEncoder = fullRouteEncoder
+    }
+
+serveSnaplet :: ((R BackendRoute -> Snap ()) -> IO b) -> IO ()
+serveSnaplet serve = do
+  config <- readConfig Nothing
+  backendRequestQueue <- newTQueueIO
+  let backendSnaplet :: MonadSnap m => R BackendRoute -> m ()
+      backendSnaplet = \case
+        BackendRouteSocket :/ (_, params) -> serveWebsocket config backendRequestQueue params
+        BackendRouteMissing :/ () -> pass
+  concurrently_
+    (localBackendProvider backendRequestQueue)
+    (serve backendSnaplet)
+
+serveWebsocket ::
+  MonadSnap m =>
+  BackendConfig ->
+  TQueue LocalBackendRequest ->
+  Map Text (Maybe Text) ->
+  m ()
+serveWebsocket config backendRequestQueue params =
+  let mayUsername = join (params ^. at "username")
+      mayPassword = join (params ^. at "password")
+      mayCreds = liftA2 (,) mayUsername mayPassword
+      action (Just (username, password))
+        | Just userConfig <- lookup username (users config)
+          , PasswordCheckSuccess <- checkPassword (mkPassword password) (passwordHash userConfig) =
+          acceptSocket backendRequestQueue username userConfig
+      action (Just (username, _))
+        | Just _ <- lookup username (users config) =
+          \connection -> do
+            say [i|Rejecting Websocket request for #{username :: Text}, wrong password.|]
+            rejectRequest connection "No valid 'username' and 'password' provided."
+      action _ = \connection -> do
+        say [i|Rejecting Websocket request #{show mayUsername :: Text}. No matching user found.|]
+        rejectRequest connection "No valid 'username' and 'password' provided."
+   in runWebSocketsSnap . action $ mayCreds
+
+acceptSocket :: TQueue LocalBackendRequest -> Text -> AccountConfig -> ServerApp
+acceptSocket backendRequestQueue username accountConfig pendingConnection = do
+  say [i|Websocket Client by user #{username} connected!|]
+  connection <- acceptRequest pendingConnection
+  forkPingThread connection 30
+  let responseCallback = sendTextData connection . Aeson.encode
+  alive <- newTVarIO True
+  requestQueue <- newTQueueIO
+  atomically . writeTQueue backendRequestQueue $
+    LocalBackendRequest
+      { userConfig = accountConfig ^. #userConfig
+      , alive
+      , responseCallback
+      , requestQueue
+      }
+  let go =
+        (try (receiveData connection) :: IO (Either ConnectionException LByteString)) >>= \case
+          Left err -> do
+            say [i|Socket for #{username} closed. With error #{err}|]
+            atomically (writeTVar alive False)
+          Right (Aeson.decode -> msg) ->
+            concurrently_ go . whenJust msg $ atomically . writeTQueue requestQueue
+  go

apps/kassandra/backend/src/Backend/Config.hs

@@ -0,0 +1,31 @@
+module Backend.Config (
+  readConfig,
+  BackendConfig (..),
+) where
+
+import Dhall (FromDhall)
+import Kassandra.Config (
+  AccountConfig,
+  Dict,
+ )
+import Kassandra.Config.Dhall (
+  DhallLoadConfig (
+    DhallLoadConfig
+  ),
+  defaultConfig,
+  defaultFile,
+  envName,
+  loadDhallConfig,
+ )
+import Kassandra.Standalone.Config (
+  BackendConfig (..),
+ )
+
+readConfig :: Maybe Text -> IO BackendConfig
+readConfig =
+  loadDhallConfig
+    DhallLoadConfig
+      { envName = "KASSANDRA_BACKEND_CONFIG"
+      , defaultFile = "~/.config/kassandra/backend.dhall"
+      , defaultConfig = "{ = }"
+      }

apps/kassandra/backend/static

@@ -0,0 +1 @@
+../static

apps/kassandra/cabal.project

@@ -0,0 +1,3 @@
+packages:
+  kassandra/
+  standalone/

apps/kassandra/cabal.project.local

@@ -0,0 +1,2 @@
+package *
+  ghc-options: -fwrite-ide-info

apps/kassandra/code.nix

@@ -0,0 +1 @@
+"16"

apps/kassandra/common-config.dhall

@@ -0,0 +1,71 @@
+let Prelude = https://prelude.dhall-lang.org/v16.0.0/package.dhall
+
+let extensions =
+      [ "AllowAmbiguousTypes"
+      , "BlockArguments"
+      , "ConstraintKinds"
+      , "DataKinds"
+      , "DeriveAnyClass"
+      , "DeriveGeneric"
+      , "DerivingStrategies"
+      , "DuplicateRecordFields"
+      , "EmptyCase"
+      , "FlexibleContexts"
+      , "FlexibleInstances"
+      , "GADTs"
+      , "LambdaCase"
+      , "MultiParamTypeClasses"
+      , "NamedFieldPuns"
+      , "OverloadedLabels"
+      , "OverloadedStrings"
+      , "PartialTypeSignatures"
+      , "PatternGuards"
+      , "PatternSynonyms"
+      , "QuasiQuotes"
+      , "RankNTypes"
+      , "RecursiveDo"
+      , "ScopedTypeVariables"
+      , "StandaloneDeriving"
+      , "StrictData"
+      , "TemplateHaskell"
+      , "TupleSections"
+      , "TypeApplications"
+      , "TypeFamilies"
+      , "UndecidableInstances"
+      , "ViewPatterns"
+      ]
+
+let ghc-options =
+      [ "-Wall"
+      , "-Wcompat"
+      , "-Wno-orphans"
+      , "-Wincomplete-uni-patterns"
+      , "-Wincomplete-record-updates"
+      , "-Wmissing-export-lists"
+      , "-Widentities"
+      , "-Wredundant-constraints"
+      , "-Wmissing-home-modules"
+      ]
+
+let multiLineList =
+      Prelude.Text.concatMapSep "\n" Text (λ(x : Text) → "    ${x}")
+
+in  ''
+    -- BEGIN dhall generated common configuration
+    -- generate with: dhall text --file common-config.dhall
+    license-file:       LICENSE
+    author:             Malte Brandy
+    maintainer:         malte.brandy@maralorn.de
+    build-type:         Simple
+    extra-source-files: CHANGELOG.md
+
+    common common-config
+      default-extensions:
+    ${multiLineList extensions}
+      ghc-options:
+    ${multiLineList ghc-options}
+      mixins:             base hiding (Prelude)
+      default-language:   Haskell2010
+    -- END dhall generated common configuration
+
+    ''

apps/kassandra/config/common/example

@@ -0,0 +1 @@
+This string comes from config/common/example

apps/kassandra/config/common/route

@@ -0,0 +1 @@
+http://localhost:8000

apps/kassandra/config/readme.md

@@ -0,0 +1,9 @@
+### Config
+
+Obelisk projects should contain a config folder with the following subfolders: common, frontend, and backend.
+
+Things that should never be transmitted to the frontend belong in backend/ (e.g., email credentials)
+
+Frontend-only configuration belongs in frontend/.
+
+Shared configuration files (e.g., the route config) belong in common/

apps/kassandra/default.nix

@@ -0,0 +1,147 @@
+{ obelisk ? import ./.obelisk/impl {
+    system = builtins.currentSystem;
+    config.android_sdk.accept_license = true;
+  }
+}:
+with obelisk;
+project ./. (
+  { pkgs, ... }:
+  let
+    inherit (pkgs.haskell.lib)
+      markUnbroken dontCheck addBuildDepend doJailbreak
+      overrideCabal
+      ;
+  in
+  {
+    android = {
+      applicationId = "de.maralorn.kassandra";
+      displayName = "Kassandra";
+      releaseKey = null;
+      isRelease = true;
+      version = {
+        code = import ./code.nix;
+        name = "0.1.0";
+      };
+    };
+    overrides = self: super: {
+      kassandra = overrideCabal super.kassandra { doHaddock = false; };
+      backend = addBuildDepend super.backend pkgs.taskwarrior;
+      clay = markUnbroken (dontCheck super.clay);
+      haskeline = dontCheck (self.callHackage "haskeline" "0.8.0.1" { });
+      repline = doJailbreak (self.callHackage "repline" "0.4.0.0" { });
+      dhall = dontCheck (self.callHackage "dhall" "1.35.0" { });
+      relude = dontCheck super.relude;
+      stm-containers = markUnbroken super.stm-containers;
+      stm-hamt = markUnbroken (doJailbreak super.stm-hamt);
+      streamly-bytestring = self.callHackageDirect
+        {
+          pkg = "streamly-bytestring";
+          ver = "0.1.2";
+          sha256 = "08xhp8zgf5n1j4v1br1dz9ih8j05vk92swp3nz9in5xajllkc7qv";
+        }
+        { };
+      streamly = self.callHackageDirect
+        {
+          pkg = "streamly";
+          ver = "0.7.0";
+          sha256 = "0hr2cz14w6nnbvhnq1fvr8v4rzyqcj3b9khf2rszyji00fmp27l1";
+        }
+        { };
+      nonempty-vector = self.callHackageDirect
+        {
+          pkg = "nonempty-vector";
+          ver = "0.1.0.0";
+          sha256 = "06abdmdy9z0w6ishiibir3qfjpqxmb4mrkhgyc4j58hd14s8rj0x";
+        }
+        { };
+      nonempty-containers = self.callHackageDirect
+        {
+          pkg = "nonempty-containers";
+          ver = "0.3.4.1";
+          sha256 = "0nbnr0az201lv09dwcxcppkfc9b05kyw4la990z5asn9737pvpr2";
+        }
+        { };
+      iCalendar = overrideCabal (doJailbreak (markUnbroken super.iCalendar)) {
+        preConfigure = ''substituteInPlace iCalendar.cabal --replace "network >=2.6 && <2.7" "network -any"'';
+      };
+      prettyprinter = self.callHackageDirect
+        {
+          pkg = "prettyprinter";
+          ver = "1.5.1";
+          sha256 = "0wx01rvgwnnmg10sh9x2whif5z12058w5djh7m5swz94wvkg5cg3";
+        }
+        { };
+      cborg-json = self.callHackageDirect
+        {
+          pkg = "cborg-json";
+          ver = "0.2.2.0";
+          sha256 = "1s7pv3jz8s1qb0ydcc5nra9f63jp4ay4d0vncv919bakf8snj4vw";
+        }
+        { };
+      generic-random = self.callHackageDirect
+        {
+          pkg = "generic-random";
+          ver = "1.3.0.0";
+          sha256 = "0m7lb40wgmyszv8l6qmarkfgs8r0idgl9agwsi72236hpvp353ad";
+        }
+        { };
+      atomic-write = self.callHackageDirect
+        {
+          pkg = "atomic-write";
+          ver = "0.2.0.7";
+          sha256 = "1r9ckwljdbw3mi8rmzmsnh89z8nhw2qnds9n271gkjgavb6hxxf3";
+        }
+        { };
+      taskwarrior = self.callHackageDirect
+        {
+          pkg = "taskwarrior";
+          ver = "0.5.0.0";
+          sha256 = "sha256-elDUtz0NSG4WHxkyCQ1CunYXWIVRj6EqkKSchPy+c3E=";
+        }
+        { };
+      base64 = self.callHackageDirect
+        {
+          pkg = "base64";
+          ver = "0.4.1";
+          sha256 = "1pz9s8bmnkrrr3v5mhkwv8vaf251vmxs87zzc5nsjsa027j9lr22";
+        }
+        { };
+      password = self.callHackageDirect
+        {
+          pkg = "password";
+          ver = "2.0.1.0";
+          sha256 = "1q99v7w6bdfpnw245aa3zaj3x7mhl9i2y7f2rzlc30g066p9jhaz";
+        }
+        { };
+      indexed-profunctors = self.callHackageDirect
+        {
+          pkg = "indexed-profunctors";
+          ver = "0.1";
+          sha256 = "0vpgbymfhnvip90jwvyniqi34lhz5n3ni1f21g81n5rap0q140za";
+        }
+        { };
+      generic-lens-core = self.callHackageDirect
+        {
+          pkg = "generic-lens-core";
+          ver = "2.0.0.0";
+          sha256 = "07parw0frqxxkjbbas9m9xb3pmpqrx9wz63m35wa6xqng9vlcscm";
+        }
+        { };
+      generic-optics = self.callHackageDirect
+        {
+          pkg = "generic-optics";
+          ver = "2.0.0.0";
+          sha256 = "0xy5k5b35w1i1zxy0dv5fk1b3zrd3hx3v5kh593k2la7ri880wmq";
+        }
+        { };
+      optics-core = self.callHackage "optics-core" "0.3.0.1" { };
+      optics-th = self.callHackage "optics-th" "0.3.0.2" { };
+      optics-extra = self.callHackage "optics-extra" "0.3" { };
+      optics = self.callHackage "optics" "0.3" { };
+    };
+    packages = {
+      kassandra = ./kassandra;
+      standalone = ./standalone;
+    };
+  }
+)

apps/kassandra/frontend/LICENSE

@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU Affero General Public License is a free, copyleft license for
+software and other kinds of works, specifically designed to ensure
+cooperation with the community in the case of network server software.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+our General Public Licenses are intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
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+                     END OF TERMS AND CONDITIONS
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+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If your software can interact with users remotely through a computer
+network, you should also make sure that it provides a way for users to
+get its source.  For example, if your program is a web application, its
+interface could display a "Source" link that leads users to an archive
+of the code.  There are many ways you could offer source, and different
+solutions will be better for different programs; see section 13 for the
+specific requirements.
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU AGPL, see
+<https://www.gnu.org/licenses/>.

apps/kassandra/frontend/frontend.cabal

@@ -0,0 +1,104 @@
+cabal-version:      2.4
+name:               frontend
+version:            0.1
+
+-- BEGIN dhall generated common configuration
+license-file:       LICENSE
+author:             Malte Brandy
+maintainer:         malte.brandy@maralorn.de
+build-type:         Simple
+extra-source-files: CHANGELOG.md
+
+common common-config
+  default-extensions:
+    AllowAmbiguousTypes
+    ConstraintKinds
+    DataKinds
+    DeriveAnyClass
+    DeriveGeneric
+    DuplicateRecordFields
+    EmptyCase
+    FlexibleContexts
+    FlexibleInstances
+    GADTs
+    LambdaCase
+    MultiParamTypeClasses
+    NamedFieldPuns
+    OverloadedLabels
+    OverloadedStrings
+    PartialTypeSignatures
+    PatternGuards
+    QuasiQuotes
+    RankNTypes
+    RecursiveDo
+    ScopedTypeVariables
+    StandaloneDeriving
+    StrictData
+    TemplateHaskell
+    TupleSections
+    TypeApplications
+    TypeFamilies
+    UndecidableInstances
+    ViewPatterns
+
+  ghc-options:
+    -Weverything -Wno-unsafe -Wno-safe -Wno-all-missed-specialisations
+    -Wno-implicit-prelude -Wno-missed-specialisations
+    -Wno-monomorphism-restriction -Wno-partial-fields
+    -Wno-missing-import-lists -Wno-orphans -Wcompat
+
+  mixins:             base hiding (Prelude)
+  default-language:   Haskell2010
+
+-- END dhall generated common configuration
+
+
+library
+  import:          common-config
+  hs-source-dirs:  src
+  build-depends:
+    , aeson
+    , base
+    , dependent-map
+    , dependent-sum-template
+    , extra
+    , generic-optics
+    , jsaddle
+    , kassandra
+    , mtl
+    , obelisk-executable-config-lookup
+    , obelisk-frontend
+    , obelisk-generated-static
+    , obelisk-route
+    , optics
+    , optics-th
+    , reflex
+    , reflex-dom
+    , scientific
+    , taskwarrior
+    , text
+    , these
+    , time
+    , unordered-containers
+    , uuid
+    , relude
+
+  exposed-modules:
+    Frontend
+    Frontend.Route
+
+executable frontend
+  import:         common-config
+  main-is:        main.hs
+  hs-source-dirs: src-bin
+  build-depends:
+    , base
+    , frontend
+    , kassandra
+    , obelisk-frontend
+    , obelisk-generated-static
+    , obelisk-route
+    , reflex-dom
+
+  ghc-options:    -threaded
+  mixins:             base hiding (Prelude)

apps/kassandra/frontend/hie.yaml

@@ -0,0 +1,2 @@
+cradle:
+   none:

apps/kassandra/frontend/src-bin/main.hs

@@ -0,0 +1,12 @@
+module Main (main) where
+
+import Frontend
+import Frontend.Route
+import Obelisk.Frontend
+import Obelisk.Route.Frontend
+import Reflex.Dom
+
+main :: IO ()
+main = do
+  let Right validFullEncoder = checkEncoder fullRouteEncoder
+  run $ runFrontend validFullEncoder frontend

apps/kassandra/frontend/src/Frontend.hs

@@ -0,0 +1,39 @@
+module Frontend (
+  frontend,
+) where
+
+import Obelisk.Frontend
+import Obelisk.Generated.Static
+import Obelisk.Route
+
+import Frontend.Route (FrontendRoute)
+import Kassandra.Css (cssAsText)
+import Kassandra.MainWidget (mainWidget)
+import Kassandra.RemoteBackendWidget (
+  CloseEvent (..),
+  remoteBackendWidget,
+ )
+import Kassandra.Types
+import qualified Reflex.Dom as D
+import Relude.Extra.Newtype
+
+-- This runs in a monad that can be run on the client or the server.
+-- To run code in a pure client or pure server context, use one of the
+-- `prerender` functions.
+frontend :: Frontend (R FrontendRoute)
+frontend =
+  Frontend
+    { _frontend_head = frontendHead
+    , _frontend_body = void $ D.prerender pass frontendBody
+    }
+
+frontendBody :: WidgetJSM t m => m ()
+frontendBody = D.dyn_ . fmap (maybe pass mainWidget)
+  =<< remoteBackendWidget (wrap D.never) Nothing
+
+css = cssAsText (static @"MaterialIcons-Regular-Outlined.otf")
+
+frontendHead :: ObeliskWidget js t route m => m ()
+frontendHead = do
+  D.el "title" $ D.text "Kassandra 2 Webversion"
+  D.elAttr "style" mempty . D.text $ css

apps/kassandra/frontend/src/Frontend/Route.hs

@@ -0,0 +1,55 @@
+module Frontend.Route (
+  BackendRoute (..),
+  FrontendRoute (..),
+  fullRouteEncoder,
+) where
+
+{- -- You will probably want these imports for composing Encoders.
+import Prelude hiding (id, (.))
+import Control.Category
+-}
+
+import qualified Control.Category
+import Data.Text (Text)
+
+--import Data.Functor.Identity
+
+import Obelisk.Route
+import Obelisk.Route.TH
+
+data BackendRoute :: Type -> Type where
+  -- | Used to handle unparseable routes.
+  BackendRouteMissing :: BackendRoute ()
+  BackendRouteSocket :: BackendRoute PageName
+
+-- You can define any routes that will be handled specially by the backend here.
+-- i.e. These do not serve the frontend, but do something different, such as serving static files.
+
+data FrontendRoute :: Type -> Type where
+  FrontendRouteMain :: FrontendRoute ()
+
+-- This type is used to define frontend routes, i.e. ones for which the backend will serve the frontend.
+
+fullRouteEncoder ::
+  Encoder
+    (Either Text)
+    Identity
+    (R (FullRoute BackendRoute FrontendRoute))
+    PageName
+fullRouteEncoder =
+  mkFullRouteEncoder
+    (FullRoute_Backend BackendRouteMissing :/ ())
+    ( \case
+        BackendRouteMissing -> PathSegment "missing" $ unitEncoder mempty
+        BackendRouteSocket -> PathSegment "socket" $ Control.Category.id
+    )
+    ( \case
+        FrontendRouteMain -> PathEnd $ unitEncoder mempty
+    )
+
+concat
+  <$> mapM
+    deriveRouteComponent
+    [ ''BackendRoute
+    , ''FrontendRoute
+    ]

apps/kassandra/hie.yaml

@@ -0,0 +1,2 @@
+cradle:
+   cabal:

apps/kassandra/kassandra/CHANGELOG.md

@@ -0,0 +1,5 @@
+# Revision history for kassandra
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.

apps/kassandra/kassandra/LICENSE

@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU Affero General Public License is a free, copyleft license for
+software and other kinds of works, specifically designed to ensure
+cooperation with the community in the case of network server software.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+our General Public Licenses are intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+  Developers that use our General Public Licenses protect your rights
+with two steps: (1) assert copyright on the software, and (2) offer
+you this License which gives you legal permission to copy, distribute
+and/or modify the software.
+
+  A secondary benefit of defending all users' freedom is that
+improvements made in alternate versions of the program, if they
+receive widespread use, become available for other developers to
+incorporate.  Many developers of free software are heartened and
+encouraged by the resulting cooperation.  However, in the case of
+software used on network servers, this result may fail to come about.
+The GNU General Public License permits making a modified version and
+letting the public access it on a server without ever releasing its
+source code to the public.
+
+  The GNU Affero General Public License is designed specifically to
+ensure that, in such cases, the modified source code becomes available
+to the community.  It requires the operator of a network server to
+provide the source code of the modified version running there to the
+users of that server.  Therefore, public use of a modified version, on
+a publicly accessible server, gives the public access to the source
+code of the modified version.
+
+  An older license, called the Affero General Public License and
+published by Affero, was designed to accomplish similar goals.  This is
+a different license, not a version of the Affero GPL, but Affero has
+released a new version of the Affero GPL which permits relicensing under
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+
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+modification follow.
+
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+or that patent license was granted, prior to 28 March 2007.
+
+  Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+  12. No Surrender of Others' Freedom.
+
+  If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
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+
+  13. Remote Network Interaction; Use with the GNU General Public License.
+
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+Program, your modified version must prominently offer all users
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+
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+
+  14. Revised Versions of this License.
+
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+
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+Program specifies that a certain numbered version of the GNU Affero General
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+
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+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
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+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
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+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
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+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
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+  You should also get your employer (if you work as a programmer) or school,
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+For more information on this, and how to apply and follow the GNU AGPL, see
+<https://www.gnu.org/licenses/>.

apps/kassandra/kassandra/Setup.hs

@@ -0,0 +1,3 @@
+import Distribution.Simple
+
+main = defaultMain

apps/kassandra/kassandra/kassandra.cabal

@@ -0,0 +1,124 @@
+cabal-version:      2.4
+name:               kassandra
+version:            0.1.0.0
+
+-- BEGIN dhall generated common configuration
+-- generate with: dhall text --file common-config.dhall
+license-file:       LICENSE
+author:             Malte Brandy
+maintainer:         malte.brandy@maralorn.de
+build-type:         Simple
+extra-source-files: CHANGELOG.md
+
+common common-config
+  default-extensions:
+    AllowAmbiguousTypes
+    ConstraintKinds
+    DataKinds
+    DeriveAnyClass
+    DeriveGeneric
+    DerivingStrategies
+    DuplicateRecordFields
+    EmptyCase
+    FlexibleContexts
+    FlexibleInstances
+    GADTs
+    GeneralizedNewtypeDeriving
+    LambdaCase
+    MultiParamTypeClasses
+    NamedFieldPuns
+    OverloadedLabels
+    OverloadedStrings
+    PartialTypeSignatures
+    PatternGuards
+    PatternSynonyms
+    QuasiQuotes
+    RankNTypes
+    RecursiveDo
+    ScopedTypeVariables
+    StandaloneDeriving
+    StrictData
+    TemplateHaskell
+    TupleSections
+    TypeApplications
+    TypeFamilies
+    UndecidableInstances
+    ViewPatterns
+
+  ghc-options:
+    -Wall -Wcompat -Wno-orphans -Wincomplete-uni-patterns
+    -Wincomplete-record-updates -Wmissing-export-lists -Widentities
+    -Wredundant-constraints -Wmissing-home-modules
+
+  mixins:             base hiding (Prelude)
+  default-language:   Haskell2010
+
+-- END dhall generated common configuration
+
+
+library
+  import:          common-config
+  exposed-modules:
+    Kassandra.Api
+    Kassandra.Calendar
+    Kassandra.Config
+    Kassandra.Css
+    Kassandra.Debug
+    Kassandra.LocalBackend
+    Kassandra.LocalBackendWidget
+    Kassandra.MainWidget
+    Kassandra.RemoteBackendWidget
+    Kassandra.SelectorWidget
+    Kassandra.State
+    Kassandra.Types
+    Kassandra.Util
+    Prelude
+
+  other-modules:
+    Kassandra.AgendaWidget
+    Kassandra.BaseWidgets
+    Kassandra.DragAndDrop
+    Kassandra.ListElementWidget
+    Kassandra.ListWidget
+    Kassandra.LogWidget
+    Kassandra.ReflexUtil
+    Kassandra.Sorting
+    Kassandra.TaskWidget
+    Kassandra.TextEditWidget
+    Kassandra.TimeWidgets
+
+  build-depends:
+    , aeson
+    , ansi-terminal
+    , async
+    , base
+    , clay
+    , containers
+    , data-default-class
+    , extra
+    , generic-optics
+    , jsaddle
+    , jsaddle-dom
+    , nonempty-containers
+    , optics
+    , optics-th
+    , password
+    , patch
+    , process
+    , reflex
+    , reflex-dom
+    , relude
+    , say
+    , scientific
+    , stm
+    , string-interpolate
+    , taskwarrior
+    , template-haskell
+    , text
+    , these
+    , time
+    , unordered-containers
+    , uuid
+    , witherable
+
+  hs-source-dirs:  src

apps/kassandra/kassandra/src/Kassandra/AgendaWidget.hs

@@ -0,0 +1,98 @@
+{-# LANGUAGE BlockArguments #-}
+
+module Kassandra.AgendaWidget (agendaWidget) where
+
+import qualified Data.Sequence as Seq
+import qualified Data.Sequence.NonEmpty as NESeq
+import Kassandra.BaseWidgets (br, button, icon)
+import Kassandra.Calendar (
+  CalendarEvent (
+    CalendarEvent,
+    calendarName,
+    comment,
+    description,
+    location,
+    time,
+    todoList,
+    uid
+  ),
+  CalendarList (entries),
+  EventTime (AllDayEvent, SimpleEvent),
+  switchToCurrentZone,
+ )
+import Kassandra.Config (DefinitionElement (..), ListItem (..))
+import Kassandra.DragAndDrop (insertArea)
+import Kassandra.ListElementWidget (AdhocContext (..), definitionElementWidget, tellList)
+import Kassandra.ReflexUtil (listWithGaps)
+import Kassandra.TextEditWidget (createTextWidget)
+import Kassandra.Types (StandardWidget, Widget, getAppState)
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+
+agendaWidget :: StandardWidget t m r e => m ()
+agendaWidget = do
+  appState <- getAppState
+  let calendarEvents = appState ^. #calendarEvents
+  void $
+    D.dyn_ $
+      calendarEvents <&> mapM_ \CalendarEvent{description, time, calendarName, location, comment, uid, todoList} ->
+        D.divClass "event" $ do
+          icon "" "event"
+          D.text description
+          whenJust location \l -> do
+            br
+            icon "" "room"
+            D.text l
+          whenJust comment \c -> do
+            br
+            icon "" "comment"
+            D.text c
+          br
+          icon "" "schedule"
+          printEventTime time
+          br
+          icon "" "list"
+          D.text calendarName
+          br
+          calendarListWidget uid todoList
+
+calendarListWidget :: StandardWidget t m r e => Text -> CalendarList -> m ()
+calendarListWidget uid calendarList = do
+  listWithGaps widget gapWidget (pure (entries calendarList))
+  newTaskEvent <- createTextWidget (button "selector" $ D.text "New Task")
+  tellList uid $ newTaskEvent <&> \content -> (#entries %~ (Seq.|> ListElement (AdHocTask content))) calendarList
+ where
+  widget definitionElement = D.divClass "definitionElement" do
+    D.divClass "definitionUI" $ do
+      delete <- button "" (D.text "x")
+      tellList uid $ delete $> (#entries %~ Seq.filter (definitionElement /=)) calendarList
+    D.divClass "element" $ definitionElementWidget (AgendaEvent uid calendarList) definitionElement
+  gapWidget around = do
+    evs <- insertArea (pure mempty) $ icon "dropHere above" "forward"
+    tellList uid $ R.attachWith (flip insertedCalendarList) (R.current around) evs
+  insertedCalendarList toInsert = \case
+    (Nothing, Nothing) -> updateOnList (const (toSeq toInsert))
+    (Just _, Nothing) -> updateOnList (<> toSeq toInsert)
+    (Nothing, Just _) -> updateOnList (toSeq toInsert <>)
+    (Just _, Just after) -> updateOnList ((\(a, b) -> a <> toSeq toInsert <> b) . Seq.breakl (== after))
+   where
+    updateOnList upd = (#entries %~ upd . Seq.filter (isNothing . flip NESeq.elemIndexL toInsert)) calendarList
+
+printEventTime :: Widget t m => EventTime -> m ()
+printEventTime (SimpleEvent start end) = do
+  showstart <- switchToCurrentZone (start ^. #time)
+  showend <- switchToCurrentZone (end ^. #time)
+  let printFullTime = toText . formatTime defaultTimeLocale "%a %Y-%m-%d %H:%M"
+  let printEndTime = toText . formatTime defaultTimeLocale "%H:%M"
+  let zone = start ^. #zone
+  D.text (printFullTime showstart)
+  icon "" "arrow_right_alt"
+  D.text (printEndTime showend)
+  D.text [i|(Defined in #{zone})|]
+printEventTime (AllDayEvent startDay endDay) = do
+  let printFullTime = toText . formatTime defaultTimeLocale "%a %Y-%m-%d"
+  D.text (printFullTime startDay)
+  when (startDay /= endDay) do
+    icon "" "arrow_right_alt"
+    D.text (printFullTime endDay)
+printEventTime _ = pass

apps/kassandra/kassandra/src/Kassandra/Api.hs

@@ -0,0 +1,29 @@
+module Kassandra.Api (
+  SocketMessage (..),
+  SocketRequest (..),
+) where
+
+import Kassandra.Calendar
+import Kassandra.Config (UIConfig)
+
+type SocketError = Text
+
+data SocketMessage
+  = TaskUpdates (NESeq Task)
+  | CalendarEvents (Seq CalendarEvent)
+  | UIConfigResponse UIConfig
+  | SocketError SocketError
+  | ConnectionEstablished
+  deriving stock (Show, Read, Generic)
+  deriving anyclass (ToJSON, FromJSON)
+makePrismLabels ''SocketMessage
+
+data SocketRequest
+  = UIConfigRequest
+  | AllTasks
+  | CalenderRequest
+  | ChangeTasks (NESeq Task)
+  | SetCalendarList Text CalendarList
+  deriving stock (Show, Read, Eq, Generic)
+  deriving anyclass (ToJSON, FromJSON)
+makePrismLabels ''SocketRequest

apps/kassandra/kassandra/src/Kassandra/BaseWidgets.hs

@@ -0,0 +1,32 @@
+module Kassandra.BaseWidgets (
+  br,
+  icon,
+  button,
+  stateWidget,
+) where
+
+import Kassandra.Types (Widget)
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+import Relude.Extra.Bifunctor (secondF)
+
+br :: D.DomBuilder t m => m ()
+br = D.el "br" pass
+
+stateWidget ::
+  Widget t m =>
+  state ->
+  (state -> m (R.Event t a, R.Event t state)) ->
+  m (R.Event t a)
+stateWidget initialState widget = do
+  eventsEvent <- D.workflowView $ stateToWorkflow initialState
+  R.switchHold R.never eventsEvent
+ where
+  stateToWorkflow = D.Workflow . secondF (fmap stateToWorkflow) . widget
+
+icon :: Widget t m => Text -> Text -> m ()
+icon cssClass = D.elClass "i" ("material-icons icon " <> cssClass) . D.text
+
+button :: Widget t m => Text -> m () -> m (R.Event t ())
+button cssClass =
+  fmap (D.domEvent D.Click . fst) . D.elClass' "span" ("button " <> cssClass)

apps/kassandra/kassandra/src/Kassandra/Calendar.hs

@@ -0,0 +1,76 @@
+module Kassandra.Calendar (
+  CalendarEvent (..),
+  CalendarList (..),
+  EventTime (..),
+  TZTime (..),
+  sortEvents,
+  tzTimeToUTC,
+  zonedDay,
+  switchToCurrentZone,
+) where
+
+import Data.Time
+import Kassandra.Config
+
+data TZTime = TZTime
+  { time :: ZonedTime
+  , zone :: Text
+  }
+  deriving stock (Show, Read, Generic)
+  deriving anyclass (ToJSON, FromJSON)
+makeLabels ''TZTime
+
+data EventTime
+  = SimpleEvent {start :: TZTime, end :: TZTime}
+  | AllDayEvent {startDay :: Day, endDay :: Day}
+  | RecurringEvent
+  deriving stock (Show, Read, Generic)
+  deriving anyclass (ToJSON, FromJSON)
+makeLabels ''EventTime
+
+data CalendarList = CalendarList
+  { entries :: Seq DefinitionElement
+  , completed :: Set Text
+  }
+  deriving stock (Eq, Show, Read, Generic)
+  deriving anyclass (ToJSON, FromJSON)
+makeLabels ''CalendarList
+
+data CalendarEvent = CalendarEvent
+  { uid :: Text
+  , time :: EventTime
+  , description :: Text
+  , location :: Maybe Text
+  , comment :: Maybe Text
+  , todoList :: CalendarList
+  , calendarName :: Text
+  }
+  deriving stock (Show, Read, Generic)
+  deriving anyclass (ToJSON, FromJSON)
+makeLabels ''CalendarEvent
+
+sortEvents :: CalendarEvent -> CalendarEvent -> Ordering
+sortEvents = sortEventTimes `on` (^. #time)
+
+sortEventTimes :: EventTime -> EventTime -> Ordering
+sortEventTimes lhs rhs = case (lhs, rhs) of
+  (SimpleEvent startTimeLhs _, SimpleEvent startTimeRhs _) -> compare (tzTimeToUTC startTimeLhs) (tzTimeToUTC startTimeRhs)
+  (AllDayEvent startDayLhs _, AllDayEvent startDayRhs _) -> compare startDayLhs startDayRhs
+  (AllDayEvent startDayLhs _, SimpleEvent startTimeRhs _) -> case compare startDayLhs (tzTimeDay startTimeRhs) of EQ -> LT; a -> a
+  (SimpleEvent startTimeLhs _, AllDayEvent startDayRhs _) -> case compare (tzTimeDay startTimeLhs) startDayRhs of EQ -> GT; a -> a
+  (_, _) -> EQ
+
+switchToCurrentZone :: MonadIO m => ZonedTime -> m ZonedTime
+switchToCurrentZone time = do
+  let inUtc = zonedTimeToUTC time
+  zone <- liftIO $ getTimeZone inUtc
+  pure $ utcToZonedTime zone inUtc
+
+tzTimeToUTC :: TZTime -> UTCTime
+tzTimeToUTC = zonedTimeToUTC . (^. #time)
+
+tzTimeDay :: TZTime -> Day
+tzTimeDay = localDay . zonedTimeToLocalTime . (^. #time)
+
+zonedDay :: ZonedTime -> Day
+zonedDay = localDay . zonedTimeToLocalTime

apps/kassandra/kassandra/src/Kassandra/Config.hs

@@ -0,0 +1,216 @@
+module Kassandra.Config (
+  AccountConfig (..),
+  RemoteBackend (..),
+  NamedBackend (..),
+  UserConfig (..),
+  LocalBackend (..),
+  Dict,
+  UIConfig (..),
+  PortConfig (..),
+  Widget (..),
+  TreeOption (..),
+  ListItem (..),
+  HabiticaTask (..),
+  HabiticaList (..),
+  DefinitionElement (..),
+  ListQuery,
+  Query,
+  QueryFilter (..),
+  TaskProperty (..),
+  UIFeatures (..),
+  PasswordConfig (..),
+  NamedListQuery (..),
+  TaskwarriorOption (..),
+) where
+
+import Data.Default.Class ( Default(..) )
+import Data.Password.Argon2 (
+  Argon2,
+  PasswordHash,
+ )
+
+type Dict = Map Text
+
+data UIFeatures = UIFeatures
+  { sortInTag :: Bool
+  , treeOption :: TreeOption
+  }
+  deriving stock (Show, Eq, Ord, Generic, Read)
+  deriving anyclass (ToJSON, FromJSON)
+
+data TreeOption = NoTree | PartOfTree | DependsTree
+  deriving stock (Show, Eq, Ord, Generic, Read)
+  deriving anyclass (ToJSON, FromJSON)
+
+data HabiticaTask = HabiticaDaily | HabiticaTodo
+  deriving stock (Show, Eq, Ord, Generic, Read)
+  deriving anyclass (ToJSON, FromJSON)
+
+data ListItem
+  = TaskwarriorTask {uuid :: UUID}
+  | AdHocTask {description :: Text}
+  | HabiticaTask {task :: HabiticaTask}
+  | Mail {id :: Text}
+  deriving stock (Show, Eq, Ord, Generic, Read)
+  deriving anyclass (ToJSON, FromJSON)
+makePrismLabels ''ListItem
+
+data HabiticaList = HabiticaDailys | HabiticaTodos
+  deriving stock (Show, Eq, Ord, Generic, Read)
+  deriving anyclass (ToJSON, FromJSON)
+
+data TaskProperty
+  = DescriptionMatches {filter :: Text}
+  | ParentBlocked
+  | Blocked
+  | Waiting
+  | Pending
+  | Completed
+  | Deleted
+  | IsParent
+  | OnList
+  | HasTag {tag :: Text}
+  | HasParent
+  deriving stock (Show, Eq, Ord, Generic, Read)
+  deriving anyclass (ToJSON, FromJSON)
+
+data TaskwarriorOption = TaskwarriorOption
+  { name :: Text
+  , value :: Text
+  }
+  deriving stock (Show, Eq, Ord, Generic)
+  deriving anyclass (Hashable)
+
+data QueryFilter
+  = HasProperty {property :: TaskProperty}
+  | HasntProperty {property :: TaskProperty}
+  deriving stock (Show, Eq, Ord, Generic, Read)
+  deriving anyclass (ToJSON, FromJSON)
+
+type Query = Seq QueryFilter
+
+data DefinitionElement
+  = ConfigList {name :: Text, limit :: Maybe Natural}
+  | ListElement {item :: ListItem}
+  | QueryList {query :: Query}
+  | TagList {name :: Text}
+  | ChildrenList {uuid :: UUID}
+  | DependenciesList {uuid :: UUID}
+  | HabiticaList {list :: HabiticaList}
+  | Mails
+  deriving stock (Show, Eq, Ord, Generic, Read)
+  deriving anyclass (ToJSON, FromJSON)
+makePrismLabels ''DefinitionElement
+
+data Widget
+  = SearchWidget
+  | DefinitionElementWidget {name :: Text, definitionElement :: DefinitionElement}
+  deriving stock (Show, Eq, Ord, Generic, Read)
+  deriving anyclass (ToJSON, FromJSON)
+
+type ListQuery = Seq DefinitionElement
+
+data NamedListQuery = NamedListQuery
+  { name :: Text
+  , list :: ListQuery
+  }
+  deriving stock (Show, Eq, Ord, Generic, Read)
+  deriving anyclass (ToJSON, FromJSON)
+
+data UIConfig = UIConfig
+  { viewList :: Seq Widget
+  , configuredLists :: Seq NamedListQuery
+  , uiFeatures :: UIFeatures
+  }
+  deriving stock (Show, Eq, Ord, Generic, Read)
+  deriving anyclass (ToJSON, FromJSON)
+makeLabels ''UIConfig
+
+instance Default UIConfig where
+  def =
+    UIConfig
+      { viewList = mempty
+      , configuredLists = mempty
+      , uiFeatures = UIFeatures True PartOfTree
+      }
+
+data PortConfig = Port {port :: Word16} | PortRange {min :: Word16, max :: Word16}
+  deriving stock (Show, Eq, Ord, Generic)
+
+data PasswordConfig = Prompt | Password {plaintext :: Text} | PasswordCommand {command :: Text}
+  deriving stock (Show, Eq, Ord, Generic)
+
+data LocalBackend
+  = TaskwarriorBackend
+      { -- | Set config file
+        taskRcPath :: Maybe Text
+      , -- | Set task data directory
+        taskDataPath :: Maybe Text
+      , -- | Override config variables
+        taskConfig :: Seq TaskwarriorOption
+      , -- | Path to taskwarrior binary. Nothing => Lookup "task" from PATH
+        taskBin :: Maybe Text
+      , -- | Use the first free port from the given range for the taskwarrior hook listener.
+        hookListenPort :: PortConfig
+      , -- | Created hooks are called ".on-add.<suffix>.<port>" and ".on-remove.<suffix>.<port>"
+        hookSuffix :: Text
+      , -- | Ensure existence of taskwarrior hook on every start
+        createHooksOnStart :: Bool
+      , -- | Remove hook on exit.
+        removeHooksOnExit :: Bool
+      }
+  | GitBackend
+      { directoryPath :: Text
+      , commit :: Bool
+      , configureMerge :: Bool
+      , createIfMissing :: Bool
+      , origin :: Maybe Text
+      , pushOnWrite :: Bool
+      , watchFiles :: Bool
+      , pullTimerSeconds :: Maybe Natural
+      }
+  deriving stock (Show, Eq, Ord, Generic)
+
+instance Default LocalBackend where
+  def =
+    TaskwarriorBackend
+      { taskRcPath = Nothing
+      , taskDataPath = Nothing
+      , taskConfig = mempty
+      , taskBin = Nothing
+      , hookListenPort = Port 6545
+      , hookSuffix = "kassandra"
+      , createHooksOnStart = True
+      , removeHooksOnExit = True
+      }
+
+data RemoteBackend a = RemoteBackend
+  { url :: Text
+  , user :: Text
+  , password :: a
+  }
+  deriving stock (Show, Eq, Ord, Generic)
+
+data NamedBackend b = NamedBackend
+  { name :: Text
+  , backend :: b
+  }
+  deriving stock (Show, Eq, Ord, Generic)
+
+data UserConfig = UserConfig
+  { localBackend :: LocalBackend
+  , uiConfig :: UIConfig
+  }
+  deriving stock (Show, Eq, Ord, Generic)
+
+instance Default UserConfig where
+  def = UserConfig def def
+
+data AccountConfig = AccountConfig
+  { passwordHash :: PasswordHash Argon2
+  , userConfig :: UserConfig
+  , filterTag :: Text
+  }
+  deriving stock (Show, Eq, Ord, Generic)
+
+makeLabels ''AccountConfig

apps/kassandra/kassandra/src/Kassandra/Css.hs

@@ -0,0 +1,166 @@
+module Kassandra.Css (
+  cssAsBS,
+  cssAsText,
+) where
+
+import Clay
+import Prelude hiding (
+  i,
+  (&),
+  (|>),
+ )
+
+cssToBS :: Css -> ByteString
+cssToBS = encodeUtf8 . cssToText
+
+cssToText :: Css -> Text
+cssToText = toStrict . render
+
+cssAsBS :: ByteString
+cssAsBS = $$([||cssToBS (css (Just ""))||])
+
+cssAsText :: Text -> Text
+cssAsText fontPath = cssToText (css (Just fontPath))
+
+fontName :: Text
+fontName = "Material Icons"
+
+css :: Maybe Text -> Css
+css fontPath = do
+  whenJust fontPath $ \fontSrc -> do
+    fontFace $ do
+      fontFamily [fontName] []
+      fontFaceSrc [FontFaceSrcUrl fontSrc (Just OpenType)]
+  let --darkBlue      = rgb 0 0 33
+      lightBlue = rgb 200 200 255
+      noMargin = margin (px 0) (px 0) (px 0) (px 0)
+      noPadding = padding (px 0) (px 0) (px 0) (px 0)
+  star ? do
+    fontFamily ["B612"] []
+    noMargin
+    noPadding
+  body ? do
+    background white
+    color black
+    minHeight (pct 100)
+  ".definitionElement" ? do
+    clear clearLeft
+  ".definitionUI" ? do
+    float floatLeft
+  ".remoteBackend" ? do
+    textAlign (alignSide sideRight)
+  ".loginDialog" ? do
+    textAlign (alignSide sideCenter)
+    padding (em 5) (em 5) (em 5) (em 5)
+  ".header" ? do
+    padding (em 0.2) (em 0.2) (em 0.2) (em 0.2)
+    background lightBlue
+    fontWeight bold
+    fontSize (em 1.5)
+  ".content" ? do
+    paddingBottom (em 4)
+  ".footer" ? do
+    position fixed
+    bottom (px 0)
+    width (pct 100)
+    padding (em 0.22) (em 0.2) (em 0.2) (em 0.2)
+    background (grayish 200)
+    color black
+  ".container" ? do
+    display flex
+    minHeight (pct 100)
+  ".dropHere" ? do
+    position absolute
+    background white
+    color black
+    border (em 0.1) solid black
+  let offset = 2
+  ".plusOne" ? marginLeft (em offset)
+  ".plusTwo" ? marginLeft (em (offset * 2))
+  ".above" ? marginTop (em (-0.8))
+  ".pane" ? width (pct 100)
+  let buttonPadding =
+        padding (em 0.3) (em 0.5) (em 0.3) (em 0.5)
+      buttonCss = do
+        display inlineBlock
+        margin (px 1) (px 1) (px 1) (px 1)
+        buttonPadding
+        border (em 0.1) solid black
+        active & do
+          background black
+          color white
+  ".button" ? buttonCss
+  ".selector" ? buttonCss
+  --".tag" ? ".icon" ? do
+  --position absolute
+  --borderRadius tagRadius tagRadius tagRadius tagRadius
+  --background lightBlue
+  --marginLeft (em (-1.1))
+  --marginTop (em 0.70)
+  --fontSize (em 0.85)
+  ".material-icons" ? do
+    fontFamily [fontName] []
+    fontWeight normal
+    fontStyle normal
+    fontSize (em 1)
+    display inlineBlock
+    lineHeight (em 1)
+    width (em 1)
+    textTransform none
+    letterSpacing normal
+    wordWrap normal
+    whiteSpace nowrap
+    direction ltr
+    "-webkit-font-smoothing" -: "antialiased"
+  ".path" ? do
+    color grey
+    fontSize (em 0.8)
+  let radius = em 0.3
+      leftBarWidth = em 1.8
+  ".activeEdit" ? buttonPadding
+  ".event" ? do
+    border (px 1) solid black
+  ".task" ? do
+    color (rgb 0 0 33)
+    border (px 1) solid black
+    background white
+    ".task" ? do
+      noMargin
+      ".parentPath" ? display none
+  ".righttask" ? do
+    width (pct 100)
+  ".statusWrapper" ? do
+    background black
+    width leftBarWidth
+    minWidth leftBarWidth
+  ".uppertask" ? do
+    display flex
+    ".edit" ? visibility visible
+  i ? cursor cursorDefault
+  ".icon" ? padding radius radius radius radius
+  ".children" ? do
+    padding (px 0) (px 0) (px 0) leftBarWidth
+    background black
+  --".slimButton" ? do
+  --marginRight (px (-5))
+  --marginLeft (px (-5))
+  let blockSize = do
+        width (em 1)
+        height (em 1)
+      bg = grayish 255
+  ".checkbox" ? do
+    marginTop (em 0.28)
+    marginBottom (em 0.28)
+    marginLeft (em 0.25)
+    display inlineBlock
+    fontSize (em 1.2)
+    blockSize
+    borderRadius (em 0.2) (em 0.2) (em 0.2) (em 0.2)
+    background bg
+    i ? do
+      ".hide" & color bg
+      ".grey" & color (grayish 160)
+      ".show" & color black
+      ".showable" & display none
+    active & i ? do
+      background black

apps/kassandra/kassandra/src/Kassandra/Debug.hs

@@ -0,0 +1,164 @@
+module Kassandra.Debug (
+  log,
+  logShow,
+  logR,
+  logRShow,
+  setLogLevel,
+  Severity (..),
+) where
+
+import Control.Concurrent (
+  ThreadId,
+  modifyMVar,
+  myThreadId,
+ )
+import GHC.Stack (
+  SrcLoc (SrcLoc),
+  srcLocModule,
+  srcLocStartLine,
+ )
+import Reflex as R
+import System.IO.Unsafe (unsafePerformIO)
+
+import qualified Debug.Trace as Trace
+import System.Console.ANSI (
+  Color (..),
+  ColorIntensity (Vivid),
+  ConsoleLayer (Foreground),
+  SGR (..),
+  setSGRCode,
+ )
+import Relude.Extra.Bifunctor
+import Relude.Extra.Enum
+import Say
+
+data Severity = Debug | Info | Warning | Error deriving stock (Show, Read, Eq, Ord)
+
+class ReflexLoggable l where
+  useLogString :: (Text -> a -> Text) -> l a -> l a
+
+instance R.Reflex t => ReflexLoggable (R.Dynamic t) where
+  useLogString f d =
+    let e' = traceEventWith (toString . f "updated Dynamic") $ updated d
+        getV0 = do
+          x <- sample $ current d
+          Trace.trace (toString $ f "initialized Dynamic" x) $ return x
+     in unsafeBuildDynamic getV0 e'
+
+instance R.Reflex t => ReflexLoggable (R.Event t) where
+  useLogString f e = traceEventWith (toString . f "triggered Event") e
+
+logR ::
+  (HasCallStack, MonadIO m, ReflexLoggable l) =>
+  Severity ->
+  (a -> Text) ->
+  l a ->
+  m (l a)
+logR severity decorate loggable = do
+  isSevere <- severeEnough severity
+  if isSevere
+    then do
+      myId <- liftIO $ modifyMVar traceID $ \a -> pure (next a, a)
+      withFrozenCallStack $ log Debug ("Registering eventTrace " <> show myId)
+      let f comment value =
+            formatMessage
+              Message
+                { msgSeverity = severity
+                , msgCallStack = callStack
+                , msgThreadId = unsafePerformIO myThreadId
+                , msgTime = unsafePerformIO getZonedTime
+                , msgComment = Just (comment <> " " <> show myId)
+                , msgContent = decorate value
+                }
+      pure $ useLogString f loggable
+    else pure loggable
+
+logRShow ::
+  (HasCallStack, MonadIO m, ReflexLoggable l, Show a) =>
+  Severity ->
+  l a ->
+  m (l a)
+logRShow a = withFrozenCallStack (logR a show)
+
+logShow :: (HasCallStack, Show a, MonadIO m) => Severity -> a -> m ()
+logShow s = withFrozenCallStack (log s . show)
+
+log :: (HasCallStack, MonadIO m) => Severity -> Text -> m ()
+log severity text = do
+  thread <- liftIO myThreadId
+  time <- liftIO getZonedTime
+  whenM (severeEnough severity) . say . formatMessage $
+    Message
+      { msgSeverity = severity
+      , msgCallStack = callStack
+      , msgThreadId = thread
+      , msgTime = time
+      , msgComment = Nothing
+      , msgContent = text
+      }
+
+{-# NOINLINE logLevel #-}
+logLevel :: MVar (Maybe Severity)
+logLevel = unsafePerformIO . newMVar $ Just Warning
+
+{-# NOINLINE traceID #-}
+traceID :: MVar Int
+traceID = unsafePerformIO . newMVar $ 0
+
+setLogLevel :: Maybe Severity -> IO ()
+setLogLevel = void . swapMVar logLevel
+
+severeEnough :: MonadIO m => Severity -> m Bool
+severeEnough severity = severeEnough' <$> readMVar logLevel
+ where
+  severeEnough' (Just minSeverity) | minSeverity <= severity = True
+  severeEnough' _ = False
+
+data Message = Message
+  { msgSeverity :: !Severity
+  , msgCallStack :: !CallStack
+  , msgThreadId :: !ThreadId
+  , msgTime :: !ZonedTime
+  , msgComment :: !(Maybe Text)
+  , msgContent :: !Text
+  }
+
+formatMessage :: Message -> Text
+formatMessage Message{msgSeverity, msgTime, msgCallStack, msgThreadId, msgComment, msgContent} =
+  showSeverity msgSeverity
+    <> showTime msgTime
+    <> showSourceLoc msgCallStack
+    <> square (show msgThreadId)
+    <> maybe "" square msgComment
+    <> msgContent
+
+square :: Text -> Text
+square t = "[" <> t <> "] "
+
+-- [30 May 2020 16:44:03.534 +00:00]
+showTime :: ZonedTime -> Text
+showTime = square . toText . formatTime defaultTimeLocale "%F %T%3Q %z"
+
+-- | Formats severity in different colours with alignment.
+showSeverity :: Severity -> Text
+showSeverity = \case
+  Debug -> color Green "[Debug]   "
+  Info -> color Blue "[Info]    "
+  Warning -> color Yellow "[Warning] "
+  Error -> color Red "[Error]   "
+ where
+  color :: Color -> Text -> Text
+  color c txt =
+    toText (setSGRCode [SetColor Foreground Vivid c]) <> txt
+      <> toText
+        (setSGRCode [Reset])
+
+showSourceLoc :: CallStack -> Text
+showSourceLoc = square . showCallStack . firstF toText . getCallStack
+ where
+  showCallStack = \case
+    [] -> "<unknown loc>"
+    [(name, SrcLoc{srcLocModule, srcLocStartLine})] ->
+      name <> "@" <> toText srcLocModule <> "#" <> show srcLocStartLine
+    (_, SrcLoc{srcLocModule, srcLocStartLine}) : (callerName, _) : _ ->
+      toText srcLocModule <> "." <> callerName <> "#" <> show srcLocStartLine

apps/kassandra/kassandra/src/Kassandra/DragAndDrop.hs

@@ -0,0 +1,83 @@
+module Kassandra.DragAndDrop (
+  childDropArea,
+  taskDropArea,
+  tellSelected,
+  insertArea,
+) where
+
+import Kassandra.Config (DefinitionElement)
+import Kassandra.Debug (
+  Severity (..),
+  logRShow,
+ )
+import Kassandra.Sorting (
+  SortPosition,
+  saveSorting,
+ )
+import Kassandra.Types (
+  AppStateChange,
+  DataChange,
+  SelectState,
+  StandardWidget,
+  TaskInfos,
+  WriteApp,
+  getSelectState,
+  getTasks,
+ )
+import Kassandra.Util (
+  lookupTask,
+  tellSingleton,
+ )
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+
+tellSelected :: (MonadIO m, WriteApp t m e) => R.Event t (Seq DefinitionElement) -> m ()
+tellSelected = tellSingleton . fmap (_Typed @AppStateChange % _Typed @SelectState #) <=< logRShow Info
+
+insertArea :: StandardWidget t m r e => R.Dynamic t (Seq DefinitionElement) -> m () -> m (R.Event t (NESeq DefinitionElement))
+insertArea blacklistD areaW = do
+  selectStateD <- getSelectState
+  let dropActive = do
+        selectState <- selectStateD
+        blacklist <- blacklistD
+        pure $ if all (`notElem` blacklist) selectState then nonEmptySeq selectState else Nothing
+  evEv <-
+    D.dyn $
+      dropActive <&> \case
+        Just entry -> do
+          dropEl <- fmap fst <$> D.element "span" D.def $ areaW
+          let event = D.domEvent D.Click dropEl
+          tellSelected (mempty <$ event)
+          pure $ entry <$ event
+        Nothing -> pure R.never
+  R.switchHold R.never evEv
+
+taskDropArea ::
+  StandardWidget t m r e =>
+  R.Dynamic t (Seq UUID) ->
+  m () ->
+  (R.Event t (NESeq TaskInfos) -> R.Event t (NESeq Task)) ->
+  m ()
+taskDropArea blacklistD areaW handler = do
+  tasksD <- getTasks
+  let blackListDefinitionElements = (#_ListElement % #_TaskwarriorTask #) <<$>> blacklistD
+  insertEvent <- insertArea blackListDefinitionElements areaW
+  let droppedTaskEvent =
+        R.attachWithMaybe
+          (\tasks -> nonEmptySeq . mapMaybe (lookupTask tasks <=< (^? #_ListElement % #_TaskwarriorTask)) . toSeq)
+          (R.current tasksD)
+          insertEvent
+  R.tellEvent $
+    fmap (_Typed @AppStateChange % _Typed @DataChange % #_ChangeTask #)
+      <$> handler droppedTaskEvent
+
+childDropArea ::
+  StandardWidget t m r e =>
+  SortPosition t ->
+  R.Dynamic t (Seq UUID) ->
+  m () ->
+  m ()
+childDropArea pos blacklistD areaW =
+  taskDropArea blacklistD areaW $
+    saveSorting (pos ^. #mode) (pos ^. #list)
+      . R.attachWith (\u t -> ((^. #task) <$> t, u)) (pos ^. #before)

apps/kassandra/kassandra/src/Kassandra/ListElementWidget.hs

@@ -0,0 +1,128 @@
+{-# LANGUAGE BlockArguments #-}
+
+module Kassandra.ListElementWidget (
+  definitionElementWidget,
+  configListWidget,
+  AdhocContext (..),
+  tellList,
+  queryWidget,
+  selectWidget,
+) where
+
+import qualified Data.HashMap.Strict as HashMap
+import qualified Data.Sequence as Seq
+import qualified Data.Set as Set
+import Kassandra.BaseWidgets (br, button, icon)
+import Kassandra.Calendar (CalendarList, completed)
+import Kassandra.Config (
+  DefinitionElement (
+    ChildrenList,
+    ConfigList,
+    DependenciesList,
+    HabiticaList,
+    ListElement,
+    Mails,
+    QueryList,
+    TagList
+  ),
+  ListItem (AdHocTask, HabiticaTask, Mail, TaskwarriorTask),
+  ListQuery,
+  NamedListQuery (NamedListQuery),
+ )
+import Kassandra.DragAndDrop (tellSelected)
+import Kassandra.ReflexUtil (smartSimpleList)
+import Kassandra.Sorting (SortMode (SortModeTag), sortTasks)
+import Kassandra.TaskWidget (
+  taskList,
+  taskTreeWidget,
+  uuidWidget,
+ )
+import Kassandra.TextEditWidget (createTextWidget)
+import Kassandra.Types (AppStateChange, DataChange (SetEventList), StandardWidget, TaskInfos, TaskState, getAppState, getSelectState, getTasks)
+import Kassandra.Util (tellNewTask, tellSingleton)
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+
+data AdhocContext = NoContext | AgendaEvent Text CalendarList | AgendaList Text (Set Text)
+
+selectWidget :: StandardWidget t m r e => DefinitionElement -> m ()
+selectWidget definitionElement = do
+  (dragEl, _) <- D.elClass' "span" "button" $ icon "" "filter_list"
+  selectStateB <- toggleContainElement definitionElement <<$>> R.current <$> getSelectState
+  tellSelected $ R.tag selectStateB (D.domEvent D.Click dragEl)
+ where
+  toggleContainElement :: DefinitionElement -> Seq DefinitionElement -> Seq DefinitionElement
+  toggleContainElement entry selectedTasks =
+    Seq.findIndexL (== entry) selectedTasks & maybe (selectedTasks |> entry) (`Seq.deleteAt` selectedTasks)
+
+listElementWidget :: StandardWidget t m r e => AdhocContext -> ListItem -> m ()
+listElementWidget context = \case
+  TaskwarriorTask uuid -> uuidWidget taskTreeWidget (pure uuid)
+  AdHocTask t -> adhocTaskWidget t context
+  HabiticaTask _ -> error "HabiticaTasks are not yet supported"
+  Mail _ -> error "Mails are not yet supported"
+
+configListWidget :: forall t m r e. StandardWidget t m r e => AdhocContext -> Text -> Maybe Natural -> m ()
+configListWidget context name limit = do
+  D.text name >> br
+  namedListQueries <- getAppState ^. mapping (#uiConfig % mapping #configuredLists)
+  D.dyn_ $ namedListQueries <&> maybe (D.text [i|No list with name "#{name}" configured.|]) (queryWidget context) . getWidget
+ where
+  getWidget = Seq.lookup 0 . mapMaybe f
+  f (NamedListQuery x query) | x == name = Just query
+  f _ = Nothing
+
+queryWidget :: StandardWidget t m r e => AdhocContext -> ListQuery -> m ()
+queryWidget context els = smartSimpleList ((>> br) . definitionElementWidget context) (pure els)
+
+tasksToShow :: Text -> TaskState -> Seq TaskInfos
+tasksToShow tag = filter inList . fromList . HashMap.elems
+ where
+  inList :: TaskInfos -> Bool
+  inList ((^. #task) -> task) = tag `Set.member` (task ^. #tags) && has (#status % #_Pending) task
+
+definitionElementWidget :: StandardWidget t m r e => AdhocContext -> DefinitionElement -> m ()
+definitionElementWidget context el = do
+  selectWidget el
+  el & \case
+    ConfigList name limit -> configListWidget context name limit
+    ListElement el' -> listElementWidget context el'
+    QueryList query -> D.text "QueryLists not implemented"
+    (TagList tag) ->
+      do
+        D.text tag
+        tasks <- getTasks
+        let showTasks = tasksToShow tag <$> tasks
+        let sortMode = SortModeTag tag
+        taskList
+          (R.constant sortMode)
+          (sortTasks sortMode <$> showTasks)
+          (R.constDyn IsEmpty)
+          taskTreeWidget
+        tellNewTask . fmap (,#tags %~ Set.insert tag)
+          =<< createTextWidget
+            (button "selector" $ D.text "Add task to list")
+    (ChildrenList uuid) -> D.text "ChildrenList not implemented"
+    (DependenciesList uuid) -> D.text "DependenciesList not implemented"
+    (HabiticaList list) -> D.text "HabiticaList not implemented"
+    Mails -> D.text "Mails not implemented"
+
+adhocTaskWidget :: StandardWidget t m r e => Text -> AdhocContext -> m ()
+adhocTaskWidget description = \case
+  AgendaEvent uid calendarList -> do
+    changeDoneStatus <- checkBox (completed calendarList)
+    D.text [i| #{description}|]
+    tellList uid $
+      changeDoneStatus <&> \case
+        True -> (#completed %~ Set.insert description) calendarList
+        False -> (#completed %~ Set.delete description) calendarList
+  AgendaList _ completed -> do
+    checkBox completed >> text
+  NoContext ->
+    checkBox mempty >> text
+ where
+  checkBox completed = if description `Set.member` completed then (False <$) <$> button "" (D.text "[x]") else (True <$) <$> button "" (D.text "[ ]")
+  text = D.text [i| #{description}|]
+
+tellList :: StandardWidget t m r e => Text -> D.Event t CalendarList -> m ()
+tellList uid listEvent = tellSingleton $ (_Typed @AppStateChange % _Typed @DataChange #) . SetEventList uid <$> listEvent

apps/kassandra/kassandra/src/Kassandra/ListWidget.hs

@@ -0,0 +1,52 @@
+module Kassandra.ListWidget (
+  listsWidget,
+  listWidget,
+) where
+
+import qualified Data.HashMap.Strict as HashMap
+import Kassandra.Config (DefinitionElement (TagList))
+import Kassandra.ListElementWidget (AdhocContext (NoContext), definitionElementWidget)
+import Kassandra.Types (
+  StandardWidget,
+  TaskState,
+  Widget,
+  getTasks,
+ )
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+
+listsWidget :: (StandardWidget t m r e) => m ()
+listsWidget = do
+  taskState <- getTasks
+  D.text "Select a list"
+  list <- listSelector (getLists <$> taskState)
+  maybeList <- R.maybeDyn list
+  D.dyn_ $ maybeList <&> maybe (D.text "Select a list") listWidget
+ where
+  getLists :: TaskState -> Seq Text
+  getLists =
+    fromList
+      . toList
+      . foldMap (^. #tags)
+      . filter (has $ #status % #_Pending)
+      . (^. mapping #task)
+      . HashMap.elems
+  listSelector ::
+    (Widget t m) => R.Dynamic t (Seq Text) -> m (R.Dynamic t (Maybe Text))
+  listSelector lists = D.el "div" $ do
+    buttons <- D.dyn $ mapM listButton <$> lists
+    buttonSum <- R.switchHold R.never $ R.leftmost . toList <$> buttons
+    R.holdDyn Nothing (Just <$> buttonSum)
+  listButton :: Widget t m => Text -> m (R.Event t Text)
+  listButton tag =
+    fmap ((tag <$) . D.domEvent D.Click . fst)
+      . D.elClass' "a" "selector"
+      . D.text
+      $ tag
+
+listWidget ::
+  forall t m r e. StandardWidget t m r e => R.Dynamic t Text -> m ()
+listWidget list = D.dyn_ (innerRenderList <$> list)
+ where
+  innerRenderList :: Text -> m ()
+  innerRenderList tag = definitionElementWidget NoContext (TagList tag)

apps/kassandra/kassandra/src/Kassandra/LocalBackend.hs

@@ -0,0 +1,41 @@
+module Kassandra.LocalBackend (
+  localClientSocket,
+  LocalBackendRequest (LocalBackendRequest, userConfig, alive, responseCallback, requestQueue),
+  BackendError (..),
+) where
+
+import Control.Concurrent.STM (TQueue, newTQueueIO, writeTQueue)
+import Kassandra.Api (SocketMessage, SocketRequest)
+import Kassandra.Config (UserConfig)
+import Kassandra.State (ClientSocket)
+import Kassandra.Types (WidgetIO)
+import qualified Reflex as R
+
+data LocalSocketState = LocalError Text | SettingUp deriving (Show)
+makePrismLabels ''LocalSocketState
+
+newtype BackendError = BackendError Text
+
+data LocalBackendRequest = LocalBackendRequest
+  { userConfig :: UserConfig
+  , alive :: TVar Bool
+  , responseCallback :: SocketMessage -> IO ()
+  , requestQueue :: TQueue SocketRequest
+  }
+makeLabels ''LocalBackendRequest
+
+localClientSocket ::
+  WidgetIO t m =>
+  TQueue LocalBackendRequest ->
+  UserConfig ->
+  m (ClientSocket t m)
+localClientSocket requestsQueue userConfig = do
+  requestQueue <- liftIO newTQueueIO
+  (socketMessageEvent, responseCallback) <- R.newTriggerEvent
+  alive <- newTVarIO True
+  let backendRequest = LocalBackendRequest{userConfig, alive, responseCallback, requestQueue}
+      clientSocket socketRequestEvent = do
+        R.performEvent_ $ atomically . mapM_ (writeTQueue requestQueue) <$> socketRequestEvent
+        pure (pure socketMessageEvent)
+  atomically $ writeTQueue requestsQueue backendRequest
+  pure clientSocket

apps/kassandra/kassandra/src/Kassandra/LocalBackendWidget.hs

@@ -0,0 +1,22 @@
+module Kassandra.LocalBackendWidget (
+  localBackendWidget,
+) where
+
+import Control.Concurrent.STM (TQueue)
+import Kassandra.Config (
+  NamedBackend (NamedBackend, backend),
+  UserConfig,
+ )
+import Kassandra.LocalBackend (LocalBackendRequest, localClientSocket)
+import Kassandra.State (StateProvider, makeStateProvider)
+import Kassandra.Types (WidgetIO)
+import qualified Reflex as R
+
+localBackendWidget ::
+  WidgetIO t m =>
+  TQueue LocalBackendRequest ->
+  NamedBackend UserConfig ->
+  m (R.Dynamic t (Maybe (StateProvider t m)))
+localBackendWidget requestsQueue NamedBackend{backend} =
+  -- TODO: Use the uiConfig
+  pure . pure . makeStateProvider <$> localClientSocket requestsQueue backend

apps/kassandra/kassandra/src/Kassandra/LogWidget.hs

@@ -0,0 +1,4 @@
+module Kassandra.LogWidget (logWidget) where
+
+logWidget :: Monad m => m ()
+logWidget = pass

apps/kassandra/kassandra/src/Kassandra/MainWidget.hs

@@ -0,0 +1,200 @@
+{-# LANGUAGE PatternSynonyms #-}
+
+module Kassandra.MainWidget (
+  mainWidget,
+) where
+
+import qualified Data.HashMap.Strict as HashMap
+import qualified Data.Sequence as Seq
+import qualified Data.Sequence.NonEmpty as NESeq
+import qualified Data.Set as Set
+import Kassandra.AgendaWidget (agendaWidget)
+import Kassandra.BaseWidgets (button, br)
+import Kassandra.Calendar (CalendarEvent)
+import Kassandra.Config (DefinitionElement, Widget (DefinitionElementWidget, SearchWidget))
+import Kassandra.Debug (
+  Severity (..),
+  log,
+  logR,
+  setLogLevel,
+ )
+import Kassandra.ListElementWidget (AdhocContext (NoContext), definitionElementWidget)
+import Kassandra.ListWidget (listsWidget)
+import Kassandra.LogWidget (logWidget)
+import Kassandra.State (StateProvider)
+import Kassandra.TaskWidget (taskTreeWidget)
+import Kassandra.TextEditWidget (createTextWidget)
+import Kassandra.Types (
+  AppState (AppState),
+  AppStateChange,
+  StandardWidget,
+  TaskInfos,
+  TaskState,
+  WidgetIO,
+  getAppState,
+  getSelectState,
+  getTasks,
+  getTime,
+ )
+import Kassandra.Util (lookupTasks, stillTodo, tellNewTask)
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+
+mainWidget :: WidgetIO t m => StateProvider t m -> m ()
+mainWidget stateProvider = do
+  -- TODO: Use ui Config
+  liftIO $ setLogLevel $ Just Info
+  log Info "Loaded Mainwidget"
+  time <- liftIO getZonedTime
+  timeDyn <-
+    fmap (utcToZonedTime (zonedTimeZone time) . (^. lensVL R.tickInfo_lastUTC))
+      <$> R.clockLossy 1 (zonedTimeToUTC time)
+  rec let (appChangeEvents, dataChangeEvents) =
+            R.fanThese $ partitionEithersNESeq <$> stateChanges
+      appData <- stateProvider dataChangeEvents
+      selectedDyn <- R.holdDyn mempty $ NESeq.last <$> appChangeEvents
+      uiConfig <- R.holdUniqDyn $ appData ^. mapping #uiConfig
+      (_, stateChanges' :: R.Event t (NESeq AppStateChange)) <-
+        R.runEventWriterT $
+          runReaderT
+            ( do
+                taskDiagnosticsWidget
+                D.divClass "content" widgetSwitcher
+                infoFooter
+            )
+            ( AppState
+                (appData ^. mapping #taskState)
+                timeDyn
+                selectedDyn
+                (appData ^. mapping #calendarData)
+                uiConfig
+            )
+      stateChanges <- logR Info (\a -> [i|StateChange: #{a}|]) stateChanges'
+  pass
+
+infoFooter :: StandardWidget t m r e => m ()
+infoFooter = D.divClass "footer" $ do
+  selectedState <- getSelectState
+  D.dyn_ $
+    selectedState <&> \a -> do
+      whenJust (nonEmptySeq a) $ \(selectedTasks :: NESeq DefinitionElement) -> do
+        forM_ selectedTasks $ \t -> D.divClass "selectedTask" (definitionElementWidget NoContext t)
+  tellNewTask . fmap (,id)
+    =<< createTextWidget
+      (button "selector" $ D.text "New Task")
+  tasks <- getTasks
+  D.el "p" $
+    D.dynText $
+      tasks <&> \taskMap ->
+        let taskList = HashMap.elems taskMap
+            countTasks a = length . filter (has (#task % #status % a))
+            pending = countTasks #_Pending taskList
+            completed = countTasks #_Completed taskList
+         in [i|#{pending} pending and #{completed} completed tasks. Kassandra-ToDo-Management|]
+
+taskDiagnosticsWidget :: StandardWidget t m r e => m ()
+taskDiagnosticsWidget = do
+  tasks <- getTasks
+  D.dynText $ do
+    tasksMap <- tasks
+    let uuids = HashMap.keys tasksMap
+        hasLoop :: Seq UUID -> UUID -> Maybe UUID
+        hasLoop seen new
+          | new `elem` seen = Just new
+          | otherwise = Seq.lookup 0 (mapMaybe (hasLoop (new <| seen)) nexts)
+         where
+          nexts = maybe mempty (^. #children) $ HashMap.lookup new tasksMap
+    pure $
+      firstJust (hasLoop mempty) uuids & \case
+        Just uuid -> "Found a loop for uuid " <> show uuid
+        Nothing -> "" -- everything fine
+
+widgets :: StandardWidget t m r e => Seq (Text, m ())
+widgets =
+  fromList
+    [ ("Agenda", agendaWidget)
+    , ("Sort", nextWidget)
+    , ("Tag Lists", listsWidget)
+    , ("Logs", logWidget)
+    ]
+
+widgetSwitcher :: forall t m r e. StandardWidget t m r e => m ()
+widgetSwitcher = do
+  uiConfigD <- getAppState ^. mapping #uiConfig
+  D.el "div" . D.dyn_ $ uiConfigD <&> withUIConfig
+ where
+  withUIConfig uiConfig = do
+    let userWidgets = mkWidget <$> uiConfig ^. #viewList
+    buttons <- forM (widgets <> userWidgets) selectButton
+    listName <- R.holdDyn (fromMaybe ("No list", pass) (Seq.lookup 0 widgets)) (R.leftmost (toList buttons))
+    D.el "div" $ D.dyn_ (snd <$> listName)
+  selectButton label =
+    (label <$) . D.domEvent D.Click . fst
+      <$> D.elClass'
+        "a"
+        "selector"
+        (D.text $ fst label)
+  mkWidget :: Widget -> (Text, m ())
+  mkWidget SearchWidget = ("Search", D.text "Not implemented")
+  mkWidget (DefinitionElementWidget name definitionElement) = (name, definitionElementWidget NoContext definitionElement)
+
+filterInbox :: UTCTime -> TaskState -> Seq CalendarEvent -> Seq TaskInfos
+filterInbox now tasks events =
+  Seq.reverse . Seq.sortOn (^. #modified) . fromList . toListOf (folded % filtered inInbox) $ tasks
+ where
+  scheduledEvents :: Set UUID
+  scheduledEvents = fromList $ toList $ mapMaybe (^? #_ListElement % #_TaskwarriorTask) <$> (^. #todoList % #entries) =<< events
+  inInbox :: TaskInfos -> Bool
+  inInbox taskInfos =
+    has (#tags % _Empty) taskInfos
+      && maybe True (now >=) (taskInfos ^. #wait)
+      && has (#status % #_Pending) taskInfos
+      && (not . any stillTodo . lookupTasks tasks) (taskInfos ^. #children)
+      && ( not
+            . any (`notElem` ["kategorie", "root"])
+            . Set.unions
+            . view (mapping #tags)
+            $ lookupTasks tasks (taskInfos ^. #parents)
+         )
+      && not (taskInfos ^. #blocked)
+      && not ((taskInfos ^. #uuid) `Set.member` scheduledEvents)
+
+getInboxTasks :: StandardWidget t m r e => m (D.Dynamic t (Seq TaskInfos))
+getInboxTasks = do
+  appState <- getAppState
+  timeDyn <- zonedTimeToUTC <<$>> getTime
+  let calendarEvents = appState ^. #calendarEvents
+  tasks <- getTasks
+  R.holdUniqDyn $ filterInbox <$> timeDyn <*> tasks <*> calendarEvents
+
+nextWidget :: StandardWidget t m r e => m ()
+nextWidget = do
+  inboxTasks <- getInboxTasks
+  unsortedTasks <-
+    fmap
+      ( filter
+          ( \task ->
+              not (Set.member "root" (task ^. #tags))
+                && has (#partof % _Nothing) task
+                && has (#status % #_Pending) task
+          )
+          . HashMap.elems
+      )
+      <$> getTasks
+  D.dynText $
+    (\x y -> if length x + length y > 0 then [i|There are #{length x} tasks in the inbox and #{length y} tasks unsorted.|] else "Nothing to do.")
+      <$> inboxTasks <*> unsortedTasks
+  inboxTaskDyn <- R.maybeDyn $ Seq.lookup 0 <$> inboxTasks
+  let decorateSortTask x = D.el "p" (D.text "Sort this task into the task tree:") *> taskTreeWidget x
+      decorateInboxTask x = D.el "p" $ do
+         D.text "Process this task from the inbox:" *> br
+         D.text "1. Does it need to be done?" *> br
+         D.text "2. Can you do it in under 2 minutes?" *> br
+         D.text "3. Should someone else do this?" *> br
+         D.text "4. Should you split this task into sub tasks?" *> br
+         D.text "5. On which tag list does it belong or when do you want to do it?" *> br
+       *> taskTreeWidget x
+      sortTask = do
+        taskDyn <- R.maybeDyn $ viaNonEmpty head <$> unsortedTasks
+        D.dyn_ (maybe pass decorateSortTask <$> taskDyn)
+  D.dyn_ (maybe sortTask decorateInboxTask <$> inboxTaskDyn)

apps/kassandra/kassandra/src/Kassandra/ReflexUtil.hs

@@ -0,0 +1,84 @@
+{-# LANGUAGE BlockArguments #-}
+{-# LANGUAGE PartialTypeSignatures #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
+module Kassandra.ReflexUtil (
+  smartSimpleList,
+  listWithGaps,
+  keyDynamic,
+) where
+
+import qualified Data.Map as Map
+import qualified Data.Patch.Map as Patch
+--import qualified Data.Patch.MapWithMove as Patch
+import qualified Data.Sequence as Seq
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+
+{- | Renders a list of widgets depending on a Dynamic list of inputs. This will
+ call the widget constructor once per value in the list.
+ When the list changes, the widget will move and reuse all values that it can
+ so that it only needs to call the constructor again, when a new value (or a
+ second copy of a same value) appears in the list.
+-}
+smartSimpleList ::
+  forall t m v.
+  (R.Adjustable t m, R.PostBuild t m, Ord v, R.MonadHold t m, MonadFix m, D.NotReady t m) =>
+  (v -> m ()) ->
+  R.Dynamic t (Seq v) ->
+  m ()
+smartSimpleList widget listElements = do
+  void $ R.simpleList (toList <$> listElements) \vDyn -> do
+     u <- R.holdUniqDyn vDyn
+     D.dyn_ . fmap widget $ u
+  --postBuild <- R.getPostBuild
+  --keyMap <- R.holdUniqDyn $ Seq.foldMapWithIndex (curry one) <$> listElements
+  --let keyMapChange =
+        --R.attachWith
+          --((Newtype.under @(Map Int (Patch.NodeInfo Int v)) fixPatchMap .) . Patch.patchThatChangesMap)
+          --(R.current keyMap)
+          --(R.updated keyMap)
+      --initialKeyMap = Patch.patchMapWithMoveInsertAll <$> R.tag (R.current keyMap) postBuild
+      --keyMapEvents = keyMapChange <> initialKeyMap
+  --void $ R.mapMapWithAdjustWithMove (const widget) mempty keyMapEvents
+
+-- | A workaround for a bug in patchThatChangesMap in patch 0.0.3.2.
+--fixPatchMap :: Map Int (Patch.NodeInfo Int v) -> Map Int (Patch.NodeInfo Int v)
+--fixPatchMap inputMap = appEndo setMoves . fmap (Patch.nodeInfoSetTo Nothing) $ inputMap
+-- where
+--  setMoves = Map.foldMapWithKey f inputMap
+--  f to' (Patch.NodeInfo (Patch.From_Move from) _) = Endo $ Map.adjust (Patch.nodeInfoSetTo (Just to')) from
+--  f _ _ = mempty
+
+listWithGaps ::
+  (R.Adjustable t m, R.PostBuild t m, R.MonadHold t m, MonadFix m, Ord v, D.NotReady t m) =>
+  (v -> m ()) ->
+  (R.Dynamic t (Maybe v, Maybe v) -> m ()) ->
+  R.Dynamic t (Seq v) ->
+  m ()
+listWithGaps widget gapWidget listD = do
+  smartSimpleList elementWidget listD
+  lastElementD <- R.holdUniqDyn $ (,Nothing) . lastOf folded <$> listD
+  gapWidget lastElementD
+ where
+  elementWidget currentElement = do
+      elementPair <- R.holdUniqDyn $ (,Just currentElement) . Map.lookup currentElement <$> prevElementsD
+      gapWidget elementPair
+      widget currentElement
+  prevElementsD = (\xs -> Map.unions . fmap one $ Seq.zip (Seq.drop 1 xs) xs) <$> listD
+
+keyDynamic ::
+  forall t k v.
+  (R.Reflex t, Ord k) =>
+  R.Incremental t (Patch.PatchMap k v) ->
+  k ->
+  R.Dynamic t (Maybe v)
+keyDynamic incremental key =
+  R.incrementalToDynamic
+    . R.unsafeMapIncremental mapMap mapPatchMap
+    $ incremental
+ where
+  mapMap :: Map k v -> Maybe v
+  mapMap = Map.lookup key
+  mapPatchMap :: Patch.PatchMap k v -> Identity (Maybe v)
+  mapPatchMap = Identity . join . Map.lookup key . Patch.unPatchMap

apps/kassandra/kassandra/src/Kassandra/RemoteBackendWidget.hs

@@ -0,0 +1,167 @@
+module Kassandra.RemoteBackendWidget (
+  remoteBackendWidget,
+  webClientSocket,
+  CloseEvent (..),
+) where
+
+import Data.Aeson (decode, encode)
+import Data.Map (elems, insert)
+import Data.Text (stripPrefix)
+import JSDOM (currentWindowUnchecked)
+import JSDOM.Custom.Window (getLocalStorage)
+import JSDOM.Generated.Storage (Storage, getItem, setItem)
+import Kassandra.Api (
+  SocketMessage,
+  SocketRequest (AllTasks),
+ )
+import Kassandra.BaseWidgets (button, stateWidget)
+import Kassandra.Config (
+  PasswordConfig (..),
+  RemoteBackend (..),
+ )
+import Kassandra.State (
+  ClientSocket,
+  StateProvider,
+  makeStateProvider,
+ )
+import Kassandra.Types (WidgetJSM)
+import Language.Javascript.JSaddle (liftJSM)
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+import Relude.Extra.Newtype (un, wrap)
+import System.Process (readCreateProcess, shell)
+
+data Connecting = LoggedOut | LoggedIn deriving (Show, Read)
+
+newtype CloseEvent t = CloseEvent (R.Event t ()) deriving newtype (Semigroup, Monoid)
+
+urlKey, userKey, passwordKey, loginStateKey :: String
+urlKey = "Url"
+userKey = "User"
+passwordKey = "Password"
+loginStateKey = "LoginState"
+
+remoteBackendWidget ::
+  forall t m.
+  WidgetJSM t m =>
+  CloseEvent t ->
+  Maybe (RemoteBackend PasswordConfig) ->
+  m (R.Dynamic t (Maybe (StateProvider t m)))
+remoteBackendWidget closeEvent mayBackend = D.divClass "remoteBackend" $ do
+  backendDyn <- maybe inputBackend getPassword mayBackend
+  responseEvent <-
+    D.dyn
+      (withBackend (closeEvent <> wrap (() <$ R.updated backendDyn)) <$> backendDyn)
+  D.holdDyn Nothing responseEvent
+ where
+  getPassword :: RemoteBackend PasswordConfig -> m (R.Dynamic t (Maybe (RemoteBackend Text)))
+  getPassword RemoteBackend{url, user, password} = do
+    fmap (pure . RemoteBackend url user) <$> case password of
+      Password plain -> pure (pure plain)
+      PasswordCommand command -> pure . Text <$> liftIO (readCreateProcess (shell $ toString command) "")
+      Prompt -> do
+        D.text [i|Enter password for #{user} on #{url}:|]
+        storage <- getStorage
+        initialPassword <- fromMaybe "" <$> getItem storage passwordKey
+        passwordInput <- textInput True initialPassword
+        let sendEvent = R.tag (inputValue passwordInput) (D.keypress D.Enter passwordInput)
+        R.performEvent_ $ sendEvent <&> setItem storage ([i|PasswordFor#{user}On#{url}|] :: String) . toString
+        R.holdDyn "" sendEvent
+  inputBackend :: m (R.Dynamic t (Maybe (RemoteBackend Text)))
+  inputBackend = do
+    protocol <- D.getLocationProtocol
+    host <- D.getLocationHost
+    let defaultUrl = protocol <> "//" <> host
+        defaultUser = ""
+        defaultPassword = ""
+    storage <- getStorage
+    initialUrl <- fromMaybe defaultUrl <$> getItem storage urlKey
+    initialUser <- fromMaybe defaultUser <$> getItem storage userKey
+    initialPassword <- fromMaybe defaultPassword <$> getItem storage passwordKey
+    initialState <- fromMaybe LoggedOut . (readMaybe =<<) <$> getItem storage loginStateKey
+    stateEvent <- stateWidget (initialState, initialUrl, initialUser, initialPassword) stateTransition
+    R.performEvent_ $
+      stateEvent <&> \(loginState, url, user, password) -> do
+        setItem storage loginStateKey (show loginState :: String)
+        setItem storage urlKey url
+        setItem storage userKey user
+        setItem storage passwordKey password
+    fmap backendFromState <$> R.holdDyn (initialState, initialUrl, initialUser, initialPassword) stateEvent
+  stateTransition (loginState, url, user, password) = case loginState of
+    LoggedOut -> D.divClass "loginDialog" $ do
+      D.text "Host:"
+      urlInput <- textInput False url
+      D.el "br" pass
+      D.text "User:"
+      userNameInput <- textInput False user
+      D.el "br" pass
+      D.text "Password:"
+      passwordInput <- textInput True password
+      D.el "br" pass
+      saveButton <- button "selector" $ D.text "Login"
+      let saveEvent =
+            liftA3
+              (LoggedIn,,,)
+              (inputValue urlInput)
+              (inputValue userNameInput)
+              (inputValue passwordInput)
+              R.<@ fold (saveButton : (D.keypress D.Enter <$> [urlInput, userNameInput, passwordInput]))
+      pure (saveEvent, saveEvent)
+    LoggedIn -> do
+      D.text [i|#{user} @ #{url}|]
+      logoutEvent <-
+        ((LoggedOut, url, user, password) <$)
+          <$> button "selector" (D.text "Logout")
+      pure (logoutEvent, logoutEvent)
+  backendFromState (LoggedIn, url, user, password) = Just $ RemoteBackend url user password
+  backendFromState (LoggedOut, _, _, _) = Nothing
+  withBackend :: CloseEvent t -> Maybe (RemoteBackend Text) -> m (Maybe (StateProvider t m))
+  withBackend innerCloseEvent = traverse (fmap makeStateProvider . webClientSocket innerCloseEvent)
+  -- TODO: Get UI Config from Server
+  textInput hidden defaultValue =
+    D.inputElement $
+      D.def
+        & lensVL D.inputElementConfig_initialValue
+        .~ defaultValue
+        & lensVL (D.inputElementConfig_elementConfig . D.elementConfig_initialAttributes)
+        .~ if hidden then "type" D.=: "password" else mempty
+  inputValue = R.current . D._inputElement_value
+
+data WebSocketState = WebSocketError Text | Connecting deriving stock (Show)
+
+getStorage :: WidgetJSM t m => m Storage
+getStorage = getLocalStorage =<< currentWindowUnchecked
+
+webClientSocket ::
+  WidgetJSM t m => CloseEvent t -> RemoteBackend Text -> m (ClientSocket t m)
+webClientSocket closeEvent backend@RemoteBackend{url, user, password} = do
+  refreshEvent <- button "selector" $ D.text "Refresh Tasks"
+  let wsUrl = maybe "ws://localhost:8000" ("ws" <>) $ stripPrefix "http" url -- TODO: Warn user about missing http
+      socketString = [i|#{wsUrl}/socket?username=#{user}&password=#{password}|]
+      clientSocket socketRequestEvent = do
+        let socketConfig =
+              D.def
+                & (lensVL D.webSocketConfig_send .~ (toList <$> (socketRequestEvent <> (one AllTasks <$ refreshEvent))))
+                  . (lensVL D.webSocketConfig_reconnect .~ True)
+                  . (lensVL D.webSocketConfig_close .~ ((3000, "Client unloaded websocket.") <$ un closeEvent))
+        storage <- getStorage
+        socket <- D.jsonWebSocket @SocketRequest @SocketMessage socketString socketConfig
+        let messages = R.fmapMaybe id $ socket ^. lensVL D.webSocket_recv
+            err = [i|Connection to kassandra server not possible. Check network connection, server url and credentials. #{backend}|]
+            close = Just err <$ socket ^. lensVL D.webSocket_close
+            open = Nothing <$ socket ^. lensVL D.webSocket_open
+            messageParseFail = maybe (Just "Failed to parse SocketMessage JSON") (const Nothing) <$> socket ^. lensVL D.webSocket_recv
+            nextStateEvent = R.leftmost [messageParseFail, close, open]
+        D.dynText . fmap (fromMaybe "") =<< R.holdDyn (Just "Websocket Connecting ...") nextStateEvent
+        let taskUpdates = (^? #_TaskUpdates) <$?> messages
+            mapKey = [i|TaskMap#{wsUrl}#{user}|] :: String
+            foldTasksToMap tasks currentMap = foldr (\task theMap -> insert (task ^. #uuid) task theMap) currentMap tasks
+            asyncSaveStorage = void . liftJSM . D.forkJSM . setItem storage mapKey . decodeUtf8 @Text . encode
+        taskMap :: Map UUID Task <- maybeToMonoid . (decode . encodeUtf8 @Text =<<) <$> getItem storage mapKey
+        tasksToSave <- R.foldDyn foldTasksToMap taskMap taskUpdates
+        -- TODO: Saving the whole Map everytime is probably quite inefficient, we should try to reduce writes by a smarter saving scheme
+        void . R.performEventAsync $ const . asyncSaveStorage <$> R.updated tasksToSave
+        ev <- R.getPostBuild
+        let cachedTasks = R.fmapMaybe (nonEmptySeq . fromList) $ elems taskMap <$ ev
+        pure . pure $ R.leftmost [messages, (#_TaskUpdates #) <$> cachedTasks]
+  pure clientSocket

apps/kassandra/kassandra/src/Kassandra/SelectorWidget.hs

@@ -0,0 +1,18 @@
+module Kassandra.SelectorWidget (
+  backendSelector,
+) where
+
+import Kassandra.Config (NamedBackend (..))
+import Kassandra.Types (Widget)
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+
+backendSelector ::
+  Widget t m => NonEmpty (NamedBackend a) -> m (R.Dynamic t (NamedBackend a))
+backendSelector backends = D.el "div" $ do
+  buttons <- forM backends $ \backend -> do
+    fmap ((backend <$) . D.domEvent D.Click . fst)
+      . D.elClass' "a" "selector"
+      . D.text
+      $ name backend
+  R.holdDyn (head backends) $ R.leftmost (toList buttons)

apps/kassandra/kassandra/src/Kassandra/Sorting.hs

@@ -0,0 +1,182 @@
+module Kassandra.Sorting (
+  sortTasks,
+  saveSorting,
+  SortPosition (SortPosition),
+  SortMode (SortModePartof, SortModeTag),
+) where
+
+import qualified Data.Aeson as Aeson
+import Data.Scientific (toRealFloat)
+import Data.Set (member)
+import Kassandra.Types (TaskInfos)
+import qualified Reflex as R
+import Relude.Extra.Foldable1 (maximum1)
+import qualified Taskwarrior.Task as Task
+import qualified Data.Sequence as Seq
+
+data SortMode = SortModePartof UUID | SortModeTag Task.Tag
+  deriving stock (Show, Eq, Ord, Generic)
+makePrismLabels ''SortMode
+
+data SortState = HasSortPos Double | WillWrite {iprev :: Double, dprev :: Int, inext :: Double, dnext :: Int}
+  deriving stock (Eq, Show, Ord, Read, Generic)
+makePrismLabels ''SortState
+
+declareFieldLabels
+  [d|
+    data SortPosition t = SortPosition
+      { mode :: R.Behavior t SortMode
+      , list :: R.Behavior t (Seq Task)
+      , before :: R.Behavior t (Maybe UUID)
+      }
+    |]
+
+sortTasks :: SortMode -> Seq TaskInfos -> Seq TaskInfos
+sortTasks mode = Seq.sortOn (getSortOrder mode . (^. #task))
+
+getSortOrder :: SortMode -> Task -> Maybe Double
+getSortOrder mode = valToNumber <=< (^. #uda % at (sortFieldName mode))
+
+valToNumber :: Aeson.Value -> Maybe Double
+valToNumber = \case
+  Aeson.Number a -> _Just # toRealFloat a
+  Aeson.String a -> readMaybe $ a ^. unpacked
+  _ -> Nothing
+
+sortFieldName :: SortMode -> Text
+sortFieldName = \case
+  SortModeTag tag -> "kassandra_tag_pos_" <> tag
+  SortModePartof _ -> "kassandra_partof_pos"
+
+setSortOrder :: SortMode -> Double -> Task -> Task
+setSortOrder mode val = #uda %~ at (sortFieldName mode) ?~ Aeson.toJSON val
+
+taskInList :: SortMode -> Task -> Bool
+taskInList (SortModePartof uuid) = (Just uuid ==) . (^. #partof)
+taskInList (SortModeTag tag) = member tag . Task.tags
+
+insertInList :: SortMode -> Task -> Task
+insertInList (SortModePartof uuid) = #partof ?~ uuid
+insertInList (SortModeTag tag) = #tags %~ addTag
+ where
+  addTag tags
+    | tag `member` tags = tags
+    | otherwise = tags <> one tag
+
+unSetSortOrder :: SortMode -> Task -> Task
+unSetSortOrder mode = #uda %~ sans (sortFieldName mode)
+
+-- ! Returns a list of tasks for which the UDA attributes need to be changed to reflect the order of the given list.
+sortingChanges :: SortMode -> Seq Task -> Seq Task
+sortingChanges mode list =
+  let addState = addSortState (getSortOrder mode)
+      assureSort delta =
+        applyUntil
+          (addState . unSetWorstUnsorted (unSetSortOrder mode) delta)
+          (tasksSorted delta)
+      sortedList = assureSort 0 $ addState list
+      finalList
+        | tasksSorted minDist sortedList = sortedList
+        | otherwise = assureSort minTouchedDist sortedList
+      getWrite (task, sortState)
+        | has #_WillWrite sortState || not (taskInList mode task) =
+          Just . setSortOrder mode (newValue sortState) . insertInList mode $ task
+        | otherwise =
+          Nothing
+   in mapMaybe getWrite finalList
+
+applyUntil :: (a -> a) -> (a -> Bool) -> a -> a
+applyUntil f condition x
+  | condition x = x
+  | otherwise = applyUntil f condition (f x)
+
+minOrder, maxOrder, minDist, minTouchedDist :: Double
+minOrder = -1
+maxOrder = - minOrder
+minDist = 10 ** (-6)
+minTouchedDist = 10 ** (-3)
+
+tasksSorted :: Show a => Double -> Seq (a, SortState) -> Bool
+tasksSorted = isSortedOn (newValue . (^. _2))
+isSortedOn :: Show a => (a -> Double) -> Double -> Seq a -> Bool
+isSortedOn f delta = \case
+  IsEmpty -> True
+  IsNonEmpty (_ :<|| IsEmpty) -> True
+  IsNonEmpty (x :<|| IsNonEmpty (y :<|| ys)) -> f x + delta < f y && isSortedOn f delta (y <| ys)
+
+unSetWorstUnsorted :: (a -> a) -> Double -> Seq (a, SortState) -> Seq a
+unSetWorstUnsorted _ _ IsEmpty = mempty
+unSetWorstUnsorted unSet delta (IsNonEmpty (x :<|| xs))
+  | ((fst <$>) -> fine, (fst <$>) -> IsNonEmpty (a :<|| alsoFine)) <-
+      Seq.breakl
+        ((worst ==) . snd)
+        (toSeq badnesses) =
+    fine <> (unSet a <| alsoFine)
+  | otherwise =
+    error "Assumed wrong invariant in unSetWorstUnsorted" -- The list of badnesses has to contain its maximum
+ where
+  badnesses = go mempty (x :<|| xs) <&> \(a, _, badness) -> (a, badness)
+  worst = maximum1 $ snd <$> badnesses
+  go :: Seq Double -> NESeq (a, SortState) -> NESeq (a, Double, Int)
+  go before ((a, s@(newValue -> value)) :<|| ys)
+    | has #_WillWrite s = (a, value, 0) :<|| rest
+    | otherwise = (a, value, foundBefore + foundAfter) :<|| rest
+   where
+    foundBefore = length $ filter (value - delta <=) before
+    (foundAfter, rest) = maybe (0, mempty) countThroughRest (nonEmptySeq ys)
+    countThroughRest list =
+      (length $ filter (\(_, int, _) -> value + delta >= int) zs, zs)
+     where
+      zs = toSeq (go (value <| before) list)
+
+newValue :: SortState -> Double
+newValue (HasSortPos x) = x
+newValue (WillWrite iprev (fromIntegral -> dprev) inext (fromIntegral -> dnext))
+  | dprev + dnext == 0 = iprev
+  | otherwise = iprev + ((inext - iprev) * dprev / (dprev + dnext))
+
+sortStateNext :: SortState -> (Double, Int)
+sortStateNext (HasSortPos a) = (a, 0)
+sortStateNext (WillWrite _ _ int d) = (int, d)
+
+addSortState :: forall a. (a -> Maybe Double) -> Seq a -> Seq (a, SortState)
+addSortState f = go (minOrder, 0)
+ where
+  go :: (Double, Int) -> Seq a -> Seq (a, SortState)
+  go (iprev, dprev) list
+    | IsEmpty <- list = mempty
+    | IsNonEmpty (x :<|| xs) <- list
+      , Just int <- f x =
+      (x, HasSortPos int) <| go (int, 0) xs
+    | IsNonEmpty (x :<|| xs) <- list
+      , next@(IsNonEmpty ((_, sortStateNext -> (inext, dnext)) :<|| _)) <-
+          go
+            (iprev, dprev + 1)
+            xs =
+      (x, WillWrite iprev (dprev + 1) inext (dnext + 1)) <| next
+    | IsNonEmpty (x :<|| _) <- list =
+      one (x, WillWrite iprev (dprev + 1) maxOrder 1)
+
+insertBefore :: Seq Task -> Seq Task -> Maybe UUID -> Seq Task
+insertBefore list toInsert = \case
+  Just uuid ->
+    let (front, back) = Seq.breakl ((== uuid) . (^. #uuid)) cleanList
+     in front <> toInsert <> back
+  Nothing -> cleanList <> toInsert
+ where
+  cleanList = filter ((`notElem` (toInsert ^. mapping #uuid)) . (^. #uuid)) list
+
+type InsertEvent t = R.Event t (NESeq Task, Maybe UUID)
+
+saveSorting ::
+  R.Reflex t =>
+  R.Behavior t SortMode ->
+  R.Behavior t (Seq Task) ->
+  InsertEvent t ->
+  R.Event t (NESeq Task)
+saveSorting modeB listB =
+  R.fmapMaybe nonEmptySeq
+    . R.attachWith attach ((,) <$> modeB <*> listB)
+ where
+  attach (mode, list) (toSeq -> tasks, before) =
+    sortingChanges mode $ insertBefore list tasks before

apps/kassandra/kassandra/src/Kassandra/State.hs

@@ -0,0 +1,104 @@
+module Kassandra.State (
+  makeStateProvider,
+  StateProvider,
+  ClientSocket,
+  DataState (..),
+) where
+
+import qualified Data.HashMap.Strict as HashMap
+import qualified Data.Sequence as Seq
+import Kassandra.Api (SocketMessage (..), SocketRequest (..))
+import Kassandra.Calendar
+import Kassandra.Config (UIConfig)
+import Kassandra.Types (
+  DataChange,
+  TaskInfos (..),
+  TaskState,
+  WidgetIO,
+ )
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+import Taskwarrior.IO (createTask)
+
+getParents :: HashMap UUID Task -> UUID -> Seq UUID
+getParents tasks = go mempty (\uuid -> (^. #partof) =<< tasks ^. at uuid)
+ where
+  go :: (Eq a, Show a) => Seq a -> (a -> Maybe a) -> a -> Seq a
+  go accu f x
+    | x `elem` accu = mempty
+    | Just next <- f x = next <| go (x <| accu) f next
+    | otherwise = mempty
+
+data DataState = DataState
+  { taskState :: TaskState
+  , uiConfig :: UIConfig
+  , calendarData :: Seq CalendarEvent
+  }
+makeLabels ''DataState
+
+type StateProvider t m = R.Event t (NESeq DataChange) -> m (R.Dynamic t DataState)
+
+type ClientSocket t m = R.Event t (NESeq SocketRequest) -> m (R.Dynamic t (R.Event t SocketMessage))
+
+makeStateProvider :: forall t m. WidgetIO t m => ClientSocket t m -> StateProvider t m
+makeStateProvider clientSocket dataChangeEvents = do
+  let fanEvent :: (b -> Maybe a) -> R.Event t (NESeq b) -> R.Event t (NESeq a)
+      fanEvent decons = R.fmapMaybe (nonEmptySeq . mapMaybe decons . toSeq)
+      createTaskEvent = fanEvent (^? #_CreateTask) dataChangeEvents
+      changeTaskEvent = fanEvent (^? #_ChangeTask) dataChangeEvents
+      setListEvent = fanEvent (^? #_SetEventList) dataChangeEvents
+  changesFromCreateEvents <- createToChangeEvent createTaskEvent
+  let localChanges = changeTaskEvent <> changesFromCreateEvents
+  rec remoteChanges <- R.switchDyn <$> clientSocket (fold eventsToSend)
+      let connectedEvent = (^? #_ConnectionEstablished) <$?> remoteChanges
+          eventsToSend =
+            [ one . ChangeTasks <$> localChanges
+            , AllTasks :<|| fromList [CalenderRequest, UIConfigRequest] <$ connectedEvent
+            , uncurry SetCalendarList <<$>> setListEvent
+            ]
+  let errorEvent = (^? #_SocketError) <$?> remoteChanges
+  calendarData <- R.holdDyn mempty $ Seq.sortBy sortEvents <$> ((^? #_CalendarEvents) <$?> remoteChanges)
+  uiConfig <- R.holdDyn D.def $ (^? #_UIConfigResponse) <$?> remoteChanges
+  D.dynText =<< R.foldDyn (<>) "" errorEvent
+  tasksStateDyn <- buildTaskInfosMap <<$>> holdTasks (localChanges <> ((^? #_TaskUpdates) <$?> remoteChanges))
+  pure (DataState <$> tasksStateDyn <*> uiConfig <*> calendarData)
+
+createToChangeEvent :: WidgetIO t m => D.Event t (NESeq (Text, Task -> Task)) -> m (D.Event t (NESeq Task))
+createToChangeEvent = R.performEvent . fmap (liftIO . mapM (\(desc, properties) -> properties <$> createTask desc))
+
+holdTasks :: WidgetIO t m => R.Event t (NESeq Task) -> m (R.Dynamic t (HashMap UUID Task))
+holdTasks = R.foldDyn foldTasks mempty
+
+foldTasks :: Foldable t => t Task -> HashMap UUID Task -> HashMap UUID Task
+foldTasks = flip (foldr (\task -> HashMap.insert (task ^. #uuid) task))
+
+buildChildrenMap :: HashMap a Task -> HashMap UUID (Seq a)
+buildChildrenMap =
+  HashMap.fromListWith (<>)
+    . mapMaybe (\(uuid, task) -> (,pure uuid) <$> task ^. #partof)
+    . HashMap.toList
+
+buildDependenciesMap :: HashMap a Task -> HashMap UUID (Seq a)
+buildDependenciesMap = HashMap.fromListWith (<>) . (HashMap.toList >=> \(uuid, task) -> (,pure uuid) <$> toList (task ^. #depends))
+
+buildTaskInfosMap :: HashMap UUID Task -> TaskState
+buildTaskInfosMap tasks =
+  HashMap.mapWithKey foldTaskMap tasks
+ where
+  foldTaskMap uuid task =
+    TaskInfos
+      { task = task
+      , children = HashMap.lookupDefault mempty uuid childrenMap
+      , parents = getParentTasks uuid
+      , revDepends = HashMap.lookupDefault mempty uuid dependenciesMap
+      , blocked = isBlockedTask task
+      }
+  isBlockedTask = isBlocked tasks
+  getParentTasks = getParents tasks
+  dependenciesMap = buildDependenciesMap tasks
+  childrenMap = buildChildrenMap tasks
+
+isBlocked :: HashMap UUID Task -> Task -> Bool
+isBlocked tasks task = any isActive . mapMaybe (`HashMap.lookup` tasks) . toList $ task ^. #depends
+ where
+  isActive t = has (#status % #_Pending) t

apps/kassandra/kassandra/src/Kassandra/TaskWidget.hs

@@ -0,0 +1,409 @@
+module Kassandra.TaskWidget (
+  taskTreeWidget,
+  taskList,
+  uuidWidget,
+) where
+
+import qualified Data.HashSet as HashSet
+import qualified Data.Sequence as Seq
+import qualified Data.Sequence.NonEmpty as NESeq
+import qualified Data.Set as Set
+import qualified Data.Text as Text
+import Kassandra.BaseWidgets (
+  button,
+  icon, br
+ )
+import Kassandra.Config (DefinitionElement)
+import Kassandra.Debug (
+  Severity (..),
+  log,
+ )
+import Kassandra.DragAndDrop (
+  childDropArea,
+  taskDropArea,
+  tellSelected,
+ )
+import Kassandra.ReflexUtil (listWithGaps)
+import Kassandra.Sorting (
+  SortMode (SortModePartof),
+  SortPosition (SortPosition),
+  sortTasks,
+ )
+import Kassandra.TextEditWidget (
+  createTextWidget,
+  lineWidget,
+ )
+import Kassandra.TimeWidgets (dateSelectionWidget)
+import Kassandra.Types (
+  AppState,
+  Have,
+  StandardWidget,
+  TaskInfos,
+  TaskTreeState,
+  TaskTreeStateChange,
+  TaskTreeWidget,
+  ToggleEvent (ToggleEvent),
+  getAppState,
+  getExpandedTasks,
+  getIsExpanded,
+  getSelectState,
+  getTime,
+ )
+import Kassandra.Util (lookupTaskM, lookupTasksDynM, lookupTasksM, stillTodo, tellNewTask, tellTask, tellToggle)
+import qualified Reflex as R
+import Reflex.Dom ((=:))
+import qualified Reflex.Dom as D
+import qualified Taskwarrior.Status as Status
+import Taskwarrior.UDA (UDA)
+
+type TaskWidget t m r e = (TaskTreeWidget t m r e, HaveTask m r)
+type HaveTask m r = Have m r TaskInfos
+
+instance LabelOptic "taskInfos" A_Lens (a, TaskInfos) (a, TaskInfos) TaskInfos TaskInfos where
+  labelOptic = _2
+
+getTaskInfos :: HaveTask m r => m TaskInfos
+getTaskInfos = ask ^. mapping typed
+
+getChildren :: TaskWidget t m r e => m (R.Dynamic t (Seq TaskInfos))
+getChildren = getTaskInfos ^. mapping #children >>= lookupTasksM
+
+taskTreeWidget ::
+  forall t m r e. StandardWidget t m r e => R.Dynamic t TaskInfos -> m ()
+taskTreeWidget taskInfosD = do
+  log Debug "Creating Tasktree Widget"
+  (appState :: AppState t) <- getAppState
+  rec treeState <-
+        R.foldDyn
+          ( flip $
+              foldr
+                ( \case
+                    ToggleEvent uuid False -> HashSet.delete uuid
+                    ToggleEvent uuid True -> HashSet.insert uuid
+                ) ::
+              NESeq ToggleEvent -> HashSet UUID -> HashSet UUID
+          )
+          mempty
+          treeStateChanges
+      (_, events :: R.Event t (NESeq TaskTreeStateChange)) <-
+        R.runEventWriterT $
+          runReaderT (taskWidget taskInfosD) (appState, treeState)
+      let (appStateChanges, treeStateChanges) =
+            R.fanThese $ partitionEithersNESeq <$> events
+  R.tellEvent (fmap (_Typed #) <$> appStateChanges)
+
+taskWidget ::
+  forall t m r e. (TaskTreeWidget t m r e) => R.Dynamic t TaskInfos -> m ()
+taskWidget taskInfos' = D.divClass "task" $ do
+  taskInfosD <- R.holdUniqDyn taskInfos'
+  appState <- getAppState
+  treeState <- ask ^. mapping typed
+  D.dyn_ $ taskInfosD <&> \taskInfos -> runReaderT widgets (appState, taskInfos, treeState)
+  childrenWidget taskInfosD
+ where
+  widgets :: ReaderT (AppState t, TaskInfos, TaskTreeState t) m ()
+  widgets = D.divClass "uppertask" $ do
+    D.divClass "statusWrapper" statusWidget
+    D.divClass "righttask" $ do
+      collapseButton
+      descriptionWidget
+      tagsWidget
+      waitWidget
+      dueWidget
+      pathWidget
+      parentButton
+      dependenciesWidget
+      addChildWidget
+      deleteButton
+      completedWidget
+      selectWidget
+      dropChildWidget
+
+pathWidget :: TaskWidget t m r e => m ()
+pathWidget = do
+  parents <- getTaskInfos ^. mapping #parents >>= lookupTasksM ^. mapping (mapping (mapping (mapping #description)))
+  D.dyn_ $ flip whenJust showPath . nonEmptySeq <$> parents
+ where
+  showPath :: TaskWidget t m r e => NESeq Text -> m ()
+  showPath parents = D.elClass "span" "parentPath" $ do
+    br
+    makePath parents
+
+makePath :: (TaskWidget t m r e) => NESeq Text -> m ()
+makePath = D.elClass "span" "path" . D.text . Text.intercalate " ≫ " . toList . NESeq.reverse
+
+dependenciesWidget :: (TaskWidget t m r e) => m ()
+dependenciesWidget = do
+  taskInfos <- getTaskInfos
+  revDepends <- filter stillTodo <<$>> lookupTasksM (taskInfos ^. #revDepends)
+  depends <- filter stillTodo <<$>> (lookupTasksM . toList) (taskInfos ^. #depends)
+  D.dyn_ $
+    whenNotNull <$> depends
+      <*> pure
+        ( \ds -> do
+            br
+            D.text "dependencies: "
+            forM_ ds $ \d -> do
+              makeOwnPath d
+              deleteEvent <- button "edit" $ icon "" "delete"
+              tellTask $ removeDep (taskInfos ^. #task) d <$ deleteEvent
+              br
+        )
+  D.dyn_ $
+    whenJust . nonEmptySeq <$> revDepends
+      <*> pure
+        ( \rds -> do
+            br
+            D.text "reverse dependencies: "
+            forM_ rds $ \rd -> do
+              makeOwnPath rd
+              deleteEvent <- button "edit" $ icon "" "delete"
+              tellTask $ removeDep (rd ^. #task) taskInfos <$ deleteEvent
+              br
+        )
+ where
+  removeDep ::
+    ( Is k1 A_Getter
+    , Is k2 A_Setter
+    , LabelOptic "depends" k2 s1 t (Set UUID) (Set UUID)
+    , LabelOptic "uuid" k1 s2 s2 UUID UUID
+    ) =>
+    s1 ->
+    s2 ->
+    t
+  removeDep task dependency =
+    #depends %~ Set.filter (dependency ^. #uuid /=) $ task
+
+makeOwnPath :: (TaskWidget t m r e) => TaskInfos -> m ()
+makeOwnPath task =
+  D.dyn_
+    . fmap (makePath . (\ps -> task ^. #description :<|| ps))
+    =<< lookupTasksM (task ^. #parents) ^. mapping (mapping (mapping #description))
+
+dropChildWidget :: (TaskWidget t m r e) => m ()
+dropChildWidget = do
+  taskInfos <- getTaskInfos
+  childrenD <- getChildren
+  showIcon <- fmap not <$> getIsExpanded (taskInfos ^. #uuid)
+  D.dyn_ $
+    when <$> showIcon
+      <*> pure
+        ( childDropArea
+            ( SortPosition
+                (SortModePartof <$> taskInfos ^. #uuid % to R.constant)
+                (childrenD ^. mapping (mapping #task) % #current)
+                (R.constant Nothing)
+            )
+            ( R.constDyn
+                (taskInfos ^. #uuid <| taskInfos ^. #parents <> taskInfos ^. #children)
+            )
+            $ icon "dropHere" "move_to_inbox"
+        )
+  taskDropArea
+    (taskInfos ^. #uuid % to (R.constDyn . one))
+    (icon "dropHere plusOne" "block")
+    $ fmap
+      ( \dependencies ->
+          one $
+            #depends
+              %~ Set.union (Set.fromList $ toList $ (^. #uuid) <$> dependencies)
+              $ taskInfos
+                ^. #task
+      )
+  taskDropArea
+    (taskInfos ^. #uuid % to (R.constDyn . one))
+    (icon "dropHere plusTwo" "schedule")
+    $ fmap (fmap ((#depends %~ Set.insert (taskInfos ^. #uuid)) . (^. #task)))
+
+tagsWidget :: forall t m r e. TaskWidget t m r e => m ()
+tagsWidget = do
+  task <- getTaskInfos ^. mapping #task
+  forM_ (task ^. #tags) $ \tag -> D.elClass "span" "tag" $ do
+    D.text tag
+    deleteEvent <- button "edit" $ icon "" "delete"
+    tellTask $ (#tags %~ Set.filter (tag /=) $ task) <$ deleteEvent
+  tagEvent <- createTextWidget . button "edit" $ icon "" "add_box"
+  tellTask $ (\tag -> #tags %~ Set.insert tag $ task) <$> tagEvent
+
+getNewUDA :: forall t m r e. TaskWidget t m r e => m UDA
+getNewUDA = one . ("partof",) . toJSON <$> getTaskInfos ^. mapping #uuid
+
+addChildWidget :: TaskWidget t m r e => m ()
+addChildWidget = do
+  descriptionEvent <- createTextWidget . button "edit" $ icon "" "add_task"
+  newUDA <- getNewUDA
+  tellNewTask $ (,#uda .~ newUDA) <$> descriptionEvent
+
+childrenWidget :: forall t m r e. TaskTreeWidget t m r e => R.Dynamic t TaskInfos -> m ()
+childrenWidget taskInfosD = do
+  expandedTasks <- getExpandedTasks
+  showChildren <-
+    R.holdUniqDyn $
+      R.zipDynWith HashSet.member (taskInfosD ^. mapping #uuid) expandedTasks
+  D.dyn_ $ showOptional <$> showChildren
+ where
+  showOptional :: Bool -> m ()
+  showOptional x = when x $ do
+    children <-
+      R.holdUniqDyn . fmap (filter stillTodo) =<< lookupTasksDynM
+        =<< R.holdUniqDyn
+          (taskInfosD ^. mapping #children)
+    let sortModeD = SortModePartof <$> taskInfosD ^. mapping #uuid
+    blacklist <-
+      R.holdUniqDyn $
+        liftA2 (<|) (taskInfosD ^. mapping #uuid) (taskInfosD ^. mapping #parents)
+    sortedList <- R.holdUniqDyn $ sortTasks <$> sortModeD <*> children
+    D.divClass "children" $
+      taskList (sortModeD ^. #current) sortedList blacklist taskWidget
+
+
+taskList ::
+  StandardWidget t m r e =>
+  R.Behavior t SortMode ->
+  R.Dynamic t (Seq TaskInfos) ->
+  R.Dynamic t (Seq UUID) ->
+  (R.Dynamic t TaskInfos -> m ()) ->
+  m ()
+taskList mode tasksD blacklistD elementWidget =
+  listWithGaps (uuidWidget elementWidget . pure) gapWidget uuidsD
+ where
+  gapWidget pairD =
+    childDropArea
+      (partialSortPosition (snd <$> R.current pairD))
+      ((maybesToSeq <$> pairD) <> blacklistD)
+      $ icon "dropHere above" "forward"
+  maybesToSeq (a, b) = fromList (toList a <> toList b)
+  partialSortPosition = SortPosition mode (tasksD ^. mapping (mapping #task) % #current)
+  uuidsD = tasksD ^. mapping (mapping #uuid)
+
+uuidWidget :: StandardWidget t m r e => (R.Dynamic t TaskInfos -> m ()) -> R.Dynamic t UUID -> m ()
+uuidWidget widget uuid = do
+  maybeCurrentTaskD <- R.maybeDyn =<< R.holdUniqDyn =<< lookupTaskM uuid
+  D.dyn_ $
+    maybe
+      (D.dynText $ (\u -> [i|Task #{u} not found.|]) <$> uuid)
+      widget
+      <$> maybeCurrentTaskD
+
+waitWidget :: forall t m r e. TaskWidget t m r e => m ()
+waitWidget = do
+  task <- getTaskInfos ^. mapping #task
+  event <- getTaskInfos >>= ((^. #wait) >>> dateSelectionWidget "wait")
+  tellTask $ flip (#wait .~) task <$> event
+
+dueWidget :: TaskWidget t m r e => m ()
+dueWidget = do
+  task <- getTaskInfos ^. mapping #task
+  event <- dateSelectionWidget "due" $ task ^. #due
+  tellTask $ flip (#due .~) task <$> event
+
+selectWidget :: TaskWidget t m r e => m ()
+selectWidget = do
+  uuid <- getTaskInfos ^. mapping (#task % #uuid)
+  (dragEl, _) <- D.elClass' "span" "button" $ icon "" "filter_list"
+  selectStateB <- toggleContainUUID uuid <<$>> R.current <$> getSelectState
+  tellSelected $ R.tag selectStateB (D.domEvent D.Click dragEl)
+ where
+  toggleContainUUID :: UUID -> Seq DefinitionElement -> Seq DefinitionElement
+  toggleContainUUID ((#_ListElement % #_TaskwarriorTask #) -> entry) selectedTasks =
+    Seq.findIndexL (== entry) selectedTasks & maybe (selectedTasks |> entry) (`Seq.deleteAt` selectedTasks)
+
+descriptionWidget :: TaskWidget t m r e => m ()
+descriptionWidget = do
+  task <- getTaskInfos ^. mapping #task
+  event <- lineWidget $ task ^. #description
+  tellTask $ flip (#description .~) task <$> event
+
+tellStatusByTime ::
+  TaskWidget t m r e => ((UTCTime -> Status) -> R.Event t a -> m ())
+tellStatusByTime handler ev = do
+  time <- getTime
+  tellStatus $ handler . zonedTimeToUTC <$> R.tag (R.current time) ev
+
+tellStatus :: TaskWidget t m r e => R.Event t Status -> m ()
+tellStatus ev = do
+  task <- getTaskInfos ^. mapping #task
+  tellTask $ flip (#status .~) task <$> ev
+
+parentButton :: forall t m r e. TaskWidget t m r e => m ()
+parentButton = do
+  task <- getTaskInfos ^. mapping #task
+  when (isn't (#partof % _Nothing) task) $ do
+    event <- button "edit" (icon "" "layers_clear")
+    tellTask $ (#partof .~ Nothing $ task) <$ event
+
+deleteButton :: forall t m r e. TaskWidget t m r e => m ()
+deleteButton = do
+  task <- getTaskInfos ^. mapping #task
+  deleteWidget $ task ^. #status
+ where
+  deleteWidget :: Status -> m ()
+  deleteWidget (Status.Deleted time) = do
+    event <- dateSelectionWidget "deleted" $ Just time
+    tellStatus $ maybe Status.Pending Status.Deleted <$> event
+  deleteWidget _ =
+    button "edit" (icon "" "delete") >>= tellStatusByTime Status.Deleted
+
+completedWidget :: forall t m r e. TaskWidget t m r e => m ()
+completedWidget = do
+  status <- getTaskInfos ^. mapping (#task % #status)
+  whenJust (status ^? #_Completed) $ \time -> do
+    event <- dateSelectionWidget "completed" $ Just time
+    tellStatus $ maybe Status.Pending Status.Completed <$> event
+
+statusWidget :: forall t m r e. TaskWidget t m r e => m ()
+statusWidget = do
+  status <- getTaskInfos <&> (\t -> (t ^. #status, t ^. #blocked))
+  widget . widgetState $ status
+ where
+  widget :: (Text, Text, Maybe (Text, Text, UTCTime -> Status.Status)) -> m ()
+  widget (iconName, showClass, handlerMay) = do
+    let (altIcon, handler) = case handlerMay of
+          Nothing -> (D.blank, const D.blank)
+          Just (altIconLabel, altClass, handlerPure) ->
+            ( D.elClass "i" ("material-icons " <> altClass <> " showable") $
+                D.text altIconLabel
+            , tellStatusByTime handlerPure . D.domEvent D.Mouseup
+            )
+    (el, ()) <- D.elAttr' "div" ("class" =: "checkbox") $ do
+      D.elClass
+        "i"
+        ( "material-icons " <> showClass
+            <> if isJust handlerMay
+              then " hideable"
+              else ""
+        )
+        $ D.text iconName
+      altIcon
+    handler el
+  widgetState ::
+    (Status, Bool) ->
+    (Text, Text, Maybe (Text, Text, UTCTime -> Status.Status))
+  widgetState = \case
+    (Status.Pending, False) ->
+      ("done", "hide", Just ("done", "grey", Status.Completed))
+    (Status.Pending, True) ->
+      ("block", "show", Just ("done", "grey", Status.Completed))
+    (Status.Completed{}, _) ->
+      ("done", "show", Just ("done", "hide", const Status.Pending))
+    (Status.Deleted{}, _) ->
+      ("delete", "show", Just ("done", "hide", const Status.Pending))
+    (Status.Recurring{}, _) -> ("repeat", "show", Nothing)
+
+collapseButton :: forall t m r e. TaskWidget t m r e => m ()
+collapseButton = do
+  taskInfos <- getTaskInfos
+  hasChildren <-
+    R.holdUniqDyn . fmap (any (has (#task % #status % #_Pending)))
+      =<< lookupTasksM
+        (taskInfos ^. #children)
+  D.dyn_ $
+    when <$> hasChildren ?? do
+      open <- getIsExpanded $ taskInfos ^. #uuid
+      let label = \case
+            True -> "unfold_less"
+            False -> "unfold_more"
+      buttonEvent <-
+        button "slimButton" $
+          D.dyn_ (icon "collapse" . label <$> open)
+      tellToggle $ taskInfos ^. #uuid <$ buttonEvent

apps/kassandra/kassandra/src/Kassandra/TextEditWidget.hs

@@ -0,0 +1,57 @@
+module Kassandra.TextEditWidget (
+  lineWidget,
+  createTextWidget,
+  enterTextWidget,
+  editText,
+) where
+
+import Kassandra.BaseWidgets (
+  button,
+  icon,
+  stateWidget,
+ )
+import Kassandra.Types (Widget)
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+
+lineWidget :: Widget t m => Text -> m (R.Event t Text)
+lineWidget text = enterTextWidget text (showText text)
+
+createTextWidget :: Widget t m => m (R.Event t ()) -> m (R.Event t Text)
+createTextWidget = enterTextWidget ""
+
+enterTextWidget :: Widget t m => Text -> m (R.Event t ()) -> m (R.Event t Text)
+enterTextWidget text altLabel = stateWidget False (selectWidget text altLabel)
+
+selectWidget ::
+  Widget t m =>
+  Text ->
+  m (R.Event t ()) ->
+  Bool ->
+  m (R.Event t Text, R.Event t Bool)
+selectWidget text _ True = do
+  editEvent <- editText text
+  pure (R.fmapMaybe id editEvent, False <$ editEvent)
+selectWidget _ altLabel False = do
+  editEvent <- altLabel
+  pure (R.never, True <$ editEvent)
+
+-- ! Takes a dynamic text and fires an event, when the user wants to edit it.
+showText :: Widget t m => Text -> m (R.Event t ())
+showText text = do
+  D.text text
+  button "edit slimButton" $ icon "" "edit"
+
+-- ! Prompts the user for a text edit and fires an event, when the user confirms the result. Nothing is cancelation.
+editText :: Widget t m => Text -> m (R.Event t (Maybe Text))
+editText text = D.elClass "span" "activeEdit" $ do
+  textinput <-
+    D.inputElement $ D.def & lensVL D.inputElementConfig_initialValue .~ text
+  saveButton <- button "" $ icon "" "save"
+  let saveEvent =
+        Just
+          <$> R.tag
+            (textinput ^. to D._inputElement_value % #current)
+            (D.keypress D.Enter textinput <> saveButton)
+  cancelEvent <- button "" $ icon "" "cancel"
+  pure $ R.leftmost [saveEvent, Nothing <$ cancelEvent]

apps/kassandra/kassandra/src/Kassandra/TimeWidgets.hs

@@ -0,0 +1,91 @@
+module Kassandra.TimeWidgets (
+  dateSelectionWidget,
+) where
+
+import Kassandra.BaseWidgets (
+  button,
+  icon,
+  stateWidget,
+ )
+import Kassandra.TextEditWidget (editText)
+import Kassandra.Types (
+  StandardWidget,
+  Widget,
+  getTime,
+ )
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+
+myFormatTime :: ZonedTime -> Text
+myFormatTime = toText . formatTime defaultTimeLocale "%Y-%m-%d %H:%M"
+
+myParseTime :: Text -> Either String LocalTime
+myParseTime ((^. unpacked) -> t) =
+  maybeToRight ("'" <> t <> "' cannot be parsed as '%Y-%m-%d %H:%M'.")
+    . parseTimeM True defaultTimeLocale "%Y-%m-%d %H:%M"
+    $ t
+
+inputDateWidget ::
+  forall t m. Widget t m => ZonedTime -> m (R.Event t (Maybe ZonedTime))
+inputDateWidget time = do
+  textMayEvent <-
+    editText @t @m . myFormatTime $ time :: m (R.Event t (Maybe Text))
+  let cancelEvent = Nothing <$ R.ffilter isNothing textMayEvent
+      textEvent = R.fmapMaybe id textMayEvent
+      (failEvent, timeEvent) = R.fanEither $ myParseTime <$> textEvent
+  warning <- R.holdDyn "" $ toText <$> failEvent
+  D.elClass "span" "warning" $ D.dynText warning
+  pure $
+    R.leftmost
+      [ Just . (\t -> time{zonedTimeToLocalTime = t}) <$> timeEvent
+      , cancelEvent
+      ]
+
+dateSelectionWidget ::
+  forall t m r e.
+  StandardWidget t m r e =>
+  Text ->
+  Maybe UTCTime ->
+  m (R.Event t (Maybe UTCTime))
+dateSelectionWidget label utcTime = do
+  timeZone <- zonedTimeZone <$> (R.sample . R.current =<< getTime)
+  let timeDyn = utcToZonedTime timeZone <$> utcTime
+  timeEvent <-
+    fmap (Just . zonedTimeToUTC)
+      <$> stateWidget False (selectTimeWidget label timeDyn)
+  deleteEvent <- deleteTime $ isJust utcTime
+  pure $ R.leftmost [deleteEvent, timeEvent]
+ where
+  deleteTime :: Bool -> m (R.Event t (Maybe a))
+  deleteTime False = pure R.never
+  deleteTime True = do
+    event <- button "edit" $ icon "" "delete"
+    pure $ Nothing <$ event
+
+selectTimeWidget ::
+  (StandardWidget t m r e) =>
+  Text ->
+  Maybe ZonedTime ->
+  Bool ->
+  m (R.Event t ZonedTime, R.Event t Bool)
+selectTimeWidget label time True = do
+  D.elClass "span" "" $ D.text (label <> ": ")
+  currentTimeDyn <- getTime
+  currentTime <- R.sample . R.current $ currentTimeDyn
+  editEvent <- inputDateWidget $ fromMaybe currentTime time
+  pure (R.fmapMaybe id editEvent, False <$ editEvent)
+selectTimeWidget label time False = do
+  editEvent <- showTime label time
+  pure (R.never, True <$ editEvent)
+
+showTime ::
+  forall t m. Widget t m => Text -> Maybe ZonedTime -> m (R.Event t ())
+showTime label = maybe create showWithButton
+ where
+  showWithButton time = do
+    D.el "span" $ D.text label
+    D.text . myFormatTime $ time
+    button "edit" $ icon "" "edit"
+  create = button "edit" $ do
+    icon "" "add"
+    D.elClass "span" "edit" $ D.text label

apps/kassandra/kassandra/src/Kassandra/Types.hs

@@ -0,0 +1,154 @@
+module Kassandra.Types (
+  Widget,
+  WidgetIO,
+  WidgetJSM,
+  TaskInfos (..),
+  TaskState,
+  AppStateChange,
+  TaskTreeState,
+  TaskTreeStateChange,
+  DataChange (..),
+  FilterState (FilterState),
+  StandardWidget,
+  TaskTreeWidget,
+  ExpandedTasks,
+  ToggleEvent (ToggleEvent),
+  WriteApp,
+  Write,
+  Have,
+  HaveApp,
+  AppState (AppState),
+  SelectState,
+  getAppState,
+  getTasks,
+  getSelectState,
+  getTime,
+  getIsExpanded,
+  getExpandedTasks,
+) where
+
+import qualified Data.Aeson as Aeson
+import Data.HashSet (member)
+import Kassandra.Calendar
+import Kassandra.Config (DefinitionElement, UIConfig)
+import Language.Javascript.JSaddle (MonadJSM)
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+import qualified Taskwarrior.Status
+import qualified Taskwarrior.Task
+import Text.Show
+
+type Widget t m =
+  ( D.DomBuilder t m
+  , D.DomBuilderSpace m ~ D.GhcjsDomSpace
+  , MonadFix m
+  , R.MonadHold t m
+  , R.PostBuild t m
+  , MonadIO m
+  , R.TriggerEvent t m
+  , R.PerformEvent t m
+  , MonadIO (R.Performable m)
+  , HasCallStack
+  )
+type WidgetJSM t m =
+  (MonadJSM (R.Performable m), MonadJSM m, WidgetIO t m)
+type WidgetIO t m = Widget t m
+data TaskInfos = TaskInfos {task :: Task, children :: Seq UUID, parents :: Seq UUID, revDepends :: Seq UUID, blocked :: Bool} deriving stock (Eq, Show, Generic)
+makeLabels ''TaskInfos
+
+type TaskState = HashMap UUID TaskInfos
+
+data DataChange = ChangeTask Task | CreateTask Text (Task -> Task) | SetEventList Text CalendarList deriving stock (Generic)
+instance Show DataChange where
+  show (ChangeTask task) = [i|ChangeTask (#{task})|]
+  show (CreateTask name _) = [i|CreateTask with name #{name}|]
+  show (SetEventList uid list) = [i|SetEventList #{uid} #{list}|]
+makePrismLabels ''DataChange
+
+data ToggleEvent = ToggleEvent UUID Bool deriving stock (Eq, Show, Generic)
+makePrismLabels ''ToggleEvent
+
+type SelectState = Seq DefinitionElement
+type AppStateChange = Either SelectState DataChange
+type TaskTreeStateChange = Either AppStateChange ToggleEvent
+
+instance {-# OVERLAPPING #-} AsType AppStateChange AppStateChange where
+  _Typed = castOptic equality
+instance {-# OVERLAPPING #-} AsType TaskTreeStateChange TaskTreeStateChange where
+  _Typed = castOptic equality
+
+data FilterState = FilterState {deletedFade :: NominalDiffTime, completedFade :: NominalDiffTime} deriving stock (Eq, Show, Generic)
+makeLabels ''FilterState
+
+type ExpandedTasks = HashSet UUID
+type TaskTreeState t = R.Dynamic t ExpandedTasks
+
+data AppState t = AppState
+  { taskState :: R.Dynamic t TaskState
+  , currentTime :: R.Dynamic t ZonedTime
+  , selectState :: R.Dynamic t SelectState
+  , calendarEvents :: R.Dynamic t (Seq CalendarEvent)
+  , uiConfig :: R.Dynamic t UIConfig
+  }
+  deriving stock (Generic)
+makeLabels ''AppState
+
+type Have m r s = (MonadReader r m, HasType s r)
+type HaveApp t m r = (R.Reflex t, Have m r (AppState t))
+type HaveTaskTree t m r = (Have m r (TaskTreeState t))
+type Write t m e s = (R.Reflex t, R.EventWriter t (NESeq e) m, AsType s e)
+type WriteApp t m e = (Write t m e AppStateChange)
+type WriteTaskTree t m e = (Write t m e TaskTreeStateChange)
+type StandardWidget t m r e = (Widget t m, HaveApp t m r, WriteApp t m e)
+type TaskTreeWidget t m r e = (StandardWidget t m r e, HaveTaskTree t m r, WriteTaskTree t m e)
+
+getIsExpanded ::
+  (Widget t m, HaveTaskTree t m r) => UUID -> m (R.Dynamic t Bool)
+getIsExpanded uuid = R.holdUniqDyn . fmap (member uuid) =<< getExpandedTasks
+
+getExpandedTasks :: HaveTaskTree t m r => m (TaskTreeState t)
+getExpandedTasks = asks (^. typed)
+
+getAppState :: (MonadReader r m, HasType (AppState t) r) => m (AppState t)
+getAppState = asks (^. typed)
+
+getTasks :: (MonadReader r m, HasType (AppState t) r) => m (R.Dynamic t TaskState)
+getTasks = getAppState ^. mapping #taskState
+
+getSelectState :: (MonadReader r m, HasType (AppState t) r) => m (R.Dynamic t SelectState)
+getSelectState = getAppState ^. mapping #selectState
+getTime ::
+  (MonadReader r m, HasType (AppState t) r) => m (R.Dynamic t ZonedTime)
+getTime = getAppState ^. mapping #currentTime
+
+deriving stock instance Generic Task
+makeLabels ''Task
+deriving stock instance Generic Status
+makeLabels ''Status
+makePrismLabels ''Status
+deriving stock instance Generic (Aeson.Result a)
+makePrismLabels ''Aeson.Result
+
+instance LabelOptic "partof" A_Lens Task Task (Maybe UUID) (Maybe UUID) where
+  labelOptic =
+    lens
+      ((^. #uda % at "partof") >=> (^? #_Success) . fromJSON)
+      (\task uuid -> #uda % at "partof" .~ (toJSON <$> uuid) $ task)
+instance LabelOptic "description" A_Lens TaskInfos TaskInfos Text Text where
+  labelOptic = #task % #description
+instance LabelOptic "uuid" A_Lens TaskInfos TaskInfos UUID UUID where
+  labelOptic = #task % #uuid
+instance LabelOptic "status" A_Lens TaskInfos TaskInfos Status Status where
+  labelOptic = #task % #status
+instance LabelOptic "tags" A_Lens TaskInfos TaskInfos (Set Text) (Set Text) where
+  labelOptic = #task % #tags
+instance LabelOptic "partof" A_Lens TaskInfos TaskInfos (Maybe UUID) (Maybe UUID) where
+  labelOptic = #task % #partof
+instance LabelOptic "modified" A_Lens TaskInfos TaskInfos (Maybe UTCTime) (Maybe UTCTime) where
+  labelOptic = #task % #modified
+instance LabelOptic "wait" A_Lens TaskInfos TaskInfos (Maybe UTCTime) (Maybe UTCTime) where
+  labelOptic = #task % #wait
+instance LabelOptic "depends" A_Lens TaskInfos TaskInfos (Set UUID) (Set UUID) where
+  labelOptic = #task % #depends
+instance (R.Reflex t, c ~ R.Behavior t a) => LabelOptic "current" A_Getter (R.Dynamic t a) (R.Dynamic t a) c c where
+  labelOptic = to R.current

apps/kassandra/kassandra/src/Kassandra/Util.hs

@@ -0,0 +1,91 @@
+module Kassandra.Util (
+  tellSingleton,
+  tellTask,
+  tellToggle,
+  tellNewTask,
+  lookupTask,
+  lookupTaskM,
+  lookupTasks,
+  lookupTasksM,
+  lookupTasksDynM,
+  defDyn,
+  defDynDyn,
+  stillTodo,
+) where
+
+import Data.HashSet (member)
+import Data.Witherable
+import Kassandra.Types (
+  AppStateChange,
+  DataChange,
+  HaveApp,
+  StandardWidget,
+  TaskInfos,
+  TaskState,
+  TaskTreeStateChange,
+  TaskTreeWidget,
+  ToggleEvent,
+  Widget,
+  WriteApp,
+  getExpandedTasks,
+  getTasks,
+ )
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+
+stillTodo :: TaskInfos -> Bool
+stillTodo = has (#status % #_Pending)
+
+tellToggle :: TaskTreeWidget t m r e => R.Event t UUID -> m ()
+tellToggle ev = do
+  expandedTasks <- getExpandedTasks <&> view #current
+  tellSingleton $
+    (_Typed @TaskTreeStateChange % _Typed @ToggleEvent #)
+      <$> R.attachWith
+        (\tasks uuid -> #_ToggleEvent # (uuid, not $ member uuid tasks))
+        expandedTasks
+        ev
+
+tellTask :: WriteApp t m e => R.Event t Task -> m ()
+tellTask =
+  tellSingleton
+    . fmap (_Typed @AppStateChange % _Typed @DataChange % #_ChangeTask #)
+
+tellNewTask :: WriteApp t m e => R.Event t (Text, Task -> Task) -> m ()
+tellNewTask =
+  tellSingleton
+    . fmap (_Typed @AppStateChange % _Typed @DataChange % #_CreateTask #)
+
+tellSingleton ::
+  (R.Reflex t, R.EventWriter t (NESeq event) m) => R.Event t event -> m ()
+tellSingleton = R.tellEvent . fmap one
+
+lookupTask :: TaskState -> UUID -> Maybe TaskInfos
+lookupTask tasks uuid = tasks ^. at uuid
+
+lookupTasks :: Filterable f => TaskState -> f UUID -> f TaskInfos
+lookupTasks tasks = mapMaybe (lookupTask tasks)
+
+lookupTaskM ::
+  StandardWidget t m r e =>
+  R.Dynamic t UUID ->
+  m (R.Dynamic t (Maybe TaskInfos))
+lookupTaskM uuid = getTasks <&> \tasks -> R.zipDynWith lookupTask tasks uuid
+
+lookupTasksM :: (Filterable f, HaveApp t m r) => f UUID -> m (R.Dynamic t (f TaskInfos))
+lookupTasksM = R.constDyn >>> lookupTasksDynM
+
+lookupTasksDynM ::
+  (Filterable f, HaveApp t m r) => R.Dynamic t (f UUID) -> m (R.Dynamic t (f TaskInfos))
+lookupTasksDynM uuids =
+  getTasks <&> \tasks -> flip lookupTasks <$> uuids <*> tasks
+
+defDyn :: Widget t m => a -> R.Dynamic t (m a) -> m (R.Dynamic t a)
+defDyn defVal = R.holdDyn defVal <=< D.dyn
+
+defDynDyn ::
+  Widget t m =>
+  R.Dynamic t a ->
+  R.Dynamic t (m (R.Dynamic t a)) ->
+  m (R.Dynamic t a)
+defDynDyn defDynamic = fmap join . defDyn defDynamic

apps/kassandra/kassandra/src/Prelude.hs

@@ -0,0 +1,132 @@
+{-# OPTIONS_GHC -Wno-deprecations #-}
+
+module Prelude (
+  module Relude,
+  module Optics,
+  module Optics.TH,
+  module Data.Text.Optics,
+  partitionEithersNE,
+  Task,
+  i,
+  (<$?>),
+  (<&?>),
+  Aeson.ToJSON,
+  Aeson.FromJSON,
+  getZonedTime,
+  addUTCTime,
+  utcToZonedTime,
+  zonedTimeZone,
+  zonedTimeToUTC,
+  firstJust,
+  IOException,
+  UTCTime,
+  catch,
+  concurrently_,
+  forConcurrently_,
+  race_,
+  makeLabels,
+  Status,
+  MonadFix,
+  ZonedTime,
+  NominalDiffTime,
+  toJSON,
+  fromJSON,
+  UUID,
+  HasField',
+  field',
+  HasAny,
+  the,
+  HasType,
+  typed,
+  AsType,
+  _Typed,
+  AsConstructor',
+  _Ctor',
+  formatTime,
+  zonedTimeToLocalTime,
+  LocalTime,
+  defaultTimeLocale,
+  parseTimeM,
+  NESeq,
+  nonEmptySeq,
+  pattern IsEmpty,
+  pattern IsNonEmpty,
+  pattern (:<||),
+  pattern (:||>),
+  (|>),(<|),
+  toSeq,
+  mapMaybe,
+  filter,
+  partitionEithersNESeq
+) where
+
+import Control.Concurrent.Async (
+  concurrently_,
+  forConcurrently_,
+  race_,
+ )
+import Control.Exception (
+  IOException,
+  catch,
+ )
+import Control.Monad.Fix (MonadFix)
+import Data.Aeson (
+  fromJSON,
+  toJSON,
+ )
+import qualified Data.Aeson as Aeson
+import Data.Generics.Product.Any (HasAny (the))
+import Data.Generics.Product.Fields (HasField' (field'))
+import Data.Generics.Product.Typed (HasType (typed))
+import Data.Generics.Sum.Constructors (AsConstructor' (_Ctor'))
+import Data.Generics.Sum.Typed (AsType (_Typed))
+import Data.List.Extra (firstJust)
+import Data.Sequence.NonEmpty hiding (filter, (|>), (<|))
+import Data.Sequence ((|>),(<|))
+import Data.String.Interpolate (i)
+import Data.Text.Optics hiding (text)
+import Data.These (partitionEithersNE, These(..))
+import Data.Witherable ( mapMaybe, (<$?>), (<&?>), filter )
+import Data.Time (
+  UTCTime,
+  addUTCTime,
+  defaultTimeLocale,
+  formatTime,
+  getZonedTime,
+  parseTimeM,
+  utcToZonedTime,
+  zonedTimeToUTC,
+  zonedTimeZone,
+ )
+import Data.Time.Clock (NominalDiffTime)
+import Data.Time.LocalTime (
+  LocalTime,
+  ZonedTime,
+  zonedTimeToLocalTime,
+ )
+import Data.UUID (UUID)
+import Language.Haskell.TH.Syntax (
+  Dec,
+  Name,
+  Q,
+ )
+import Optics hiding ((|>), (<|))
+import Optics.TH
+import Relude hiding (uncons, mapMaybe, filter)
+import Relude.Extra.Foldable1
+import Taskwarrior.Status (Status)
+import Taskwarrior.Task (Task)
+
+instance One (NESeq a) where
+  type OneItem (NESeq a) = a
+  one = singleton
+
+instance Foldable1 NESeq where
+   foldMap1 f = foldMapWithIndex (const f)
+
+-- (lensField .~ noPrefixNamer $ fieldLabelsRules) == noPrefixFieldLabels but only in optics-th 0.2
+makeLabels :: Name -> Q [Dec]
+makeLabels = makeFieldLabelsWith noPrefixFieldLabels
+
+partitionEithersNESeq :: NESeq (Either a b) -> These (NESeq a) (NESeq b)
+partitionEithersNESeq = fold1 . fmap (either (This . one) (That . one))

apps/kassandra/nix/sources.json

@@ -0,0 +1,14 @@
+{
+    "nixpkgs": {
+        "branch": "nixos-unstable",
+        "description": "Nix Packages collection",
+        "homepage": "",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "f1c167688a6f81f4a51ab542e5f476c8c595e457",
+        "sha256": "00ac3axj7jdfcajj3macdydf9w9bvqqvgrqkh1xxr3rfi9q2fz1v",
+        "type": "tarball",
+        "url": "https://github.com/NixOS/nixpkgs/archive/f1c167688a6f81f4a51ab542e5f476c8c595e457.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    }
+}

apps/kassandra/nix/sources.nix

@@ -0,0 +1,194 @@
+# This file has been generated by Niv.
+
+let
+
+  #
+  # The fetchers. fetch_<type> fetches specs of type <type>.
+  #
+
+  fetch_file = pkgs: name: spec:
+    let
+      name' = sanitizeName name + "-src";
+    in
+      if spec.builtin or true then
+        builtins_fetchurl { inherit (spec) url sha256; name = name'; }
+      else
+        pkgs.fetchurl { inherit (spec) url sha256; name = name'; };
+
+  fetch_tarball = pkgs: name: spec:
+    let
+      name' = sanitizeName name + "-src";
+    in
+      if spec.builtin or true then
+        builtins_fetchTarball { name = name'; inherit (spec) url sha256; }
+      else
+        pkgs.fetchzip { name = name'; inherit (spec) url sha256; };
+
+  fetch_git = name: spec:
+    let
+      ref =
+        if spec ? ref then spec.ref else
+          if spec ? branch then "refs/heads/${spec.branch}" else
+            if spec ? tag then "refs/tags/${spec.tag}" else
+              abort "In git source '${name}': Please specify `ref`, `tag` or `branch`!";
+      submodules = if spec ? submodules then spec.submodules else false;
+      submoduleArg =
+        let
+          nixSupportsSubmodules = builtins.compareVersions builtins.nixVersion "2.4" >= 0;
+          emptyArgWithWarning =
+            if submodules == true
+            then
+              builtins.trace
+                (
+                  "The niv input \"${name}\" uses submodules "
+                  + "but your nix's (${builtins.nixVersion}) builtins.fetchGit "
+                  + "does not support them"
+                )
+                {}
+            else {};
+        in
+          if nixSupportsSubmodules
+          then { inherit submodules; }
+          else emptyArgWithWarning;
+    in
+      builtins.fetchGit
+        ({ url = spec.repo; inherit (spec) rev; inherit ref; } // submoduleArg);
+
+  fetch_local = spec: spec.path;
+
+  fetch_builtin-tarball = name: throw
+    ''[${name}] The niv type "builtin-tarball" is deprecated. You should instead use `builtin = true`.
+        $ niv modify ${name} -a type=tarball -a builtin=true'';
+
+  fetch_builtin-url = name: throw
+    ''[${name}] The niv type "builtin-url" will soon be deprecated. You should instead use `builtin = true`.
+        $ niv modify ${name} -a type=file -a builtin=true'';
+
+  #
+  # Various helpers
+  #
+
+  # https://github.com/NixOS/nixpkgs/pull/83241/files#diff-c6f540a4f3bfa4b0e8b6bafd4cd54e8bR695
+  sanitizeName = name:
+    (
+      concatMapStrings (s: if builtins.isList s then "-" else s)
+        (
+          builtins.split "[^[:alnum:]+._?=-]+"
+            ((x: builtins.elemAt (builtins.match "\\.*(.*)" x) 0) name)
+        )
+    );
+
+  # The set of packages used when specs are fetched using non-builtins.
+  mkPkgs = sources: system:
+    let
+      sourcesNixpkgs =
+        import (builtins_fetchTarball { inherit (sources.nixpkgs) url sha256; }) { inherit system; };
+      hasNixpkgsPath = builtins.any (x: x.prefix == "nixpkgs") builtins.nixPath;
+      hasThisAsNixpkgsPath = <nixpkgs> == ./.;
+    in
+      if builtins.hasAttr "nixpkgs" sources
+      then sourcesNixpkgs
+      else if hasNixpkgsPath && ! hasThisAsNixpkgsPath then
+        import <nixpkgs> {}
+      else
+        abort
+          ''
+            Please specify either <nixpkgs> (through -I or NIX_PATH=nixpkgs=...) or
+            add a package called "nixpkgs" to your sources.json.
+          '';
+
+  # The actual fetching function.
+  fetch = pkgs: name: spec:
+
+    if ! builtins.hasAttr "type" spec then
+      abort "ERROR: niv spec ${name} does not have a 'type' attribute"
+    else if spec.type == "file" then fetch_file pkgs name spec
+    else if spec.type == "tarball" then fetch_tarball pkgs name spec
+    else if spec.type == "git" then fetch_git name spec
+    else if spec.type == "local" then fetch_local spec
+    else if spec.type == "builtin-tarball" then fetch_builtin-tarball name
+    else if spec.type == "builtin-url" then fetch_builtin-url name
+    else
+      abort "ERROR: niv spec ${name} has unknown type ${builtins.toJSON spec.type}";
+
+  # If the environment variable NIV_OVERRIDE_${name} is set, then use
+  # the path directly as opposed to the fetched source.
+  replace = name: drv:
+    let
+      saneName = stringAsChars (c: if isNull (builtins.match "[a-zA-Z0-9]" c) then "_" else c) name;
+      ersatz = builtins.getEnv "NIV_OVERRIDE_${saneName}";
+    in
+      if ersatz == "" then drv else
+        # this turns the string into an actual Nix path (for both absolute and
+        # relative paths)
+        if builtins.substring 0 1 ersatz == "/" then /. + ersatz else /. + builtins.getEnv "PWD" + "/${ersatz}";
+
+  # Ports of functions for older nix versions
+
+  # a Nix version of mapAttrs if the built-in doesn't exist
+  mapAttrs = builtins.mapAttrs or (
+    f: set: with builtins;
+    listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set))
+  );
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/lists.nix#L295
+  range = first: last: if first > last then [] else builtins.genList (n: first + n) (last - first + 1);
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L257
+  stringToCharacters = s: map (p: builtins.substring p 1 s) (range 0 (builtins.stringLength s - 1));
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L269
+  stringAsChars = f: s: concatStrings (map f (stringToCharacters s));
+  concatMapStrings = f: list: concatStrings (map f list);
+  concatStrings = builtins.concatStringsSep "";
+
+  # https://github.com/NixOS/nixpkgs/blob/8a9f58a375c401b96da862d969f66429def1d118/lib/attrsets.nix#L331
+  optionalAttrs = cond: as: if cond then as else {};
+
+  # fetchTarball version that is compatible between all the versions of Nix
+  builtins_fetchTarball = { url, name ? null, sha256 }@attrs:
+    let
+      inherit (builtins) lessThan nixVersion fetchTarball;
+    in
+      if lessThan nixVersion "1.12" then
+        fetchTarball ({ inherit url; } // (optionalAttrs (!isNull name) { inherit name; }))
+      else
+        fetchTarball attrs;
+
+  # fetchurl version that is compatible between all the versions of Nix
+  builtins_fetchurl = { url, name ? null, sha256 }@attrs:
+    let
+      inherit (builtins) lessThan nixVersion fetchurl;
+    in
+      if lessThan nixVersion "1.12" then
+        fetchurl ({ inherit url; } // (optionalAttrs (!isNull name) { inherit name; }))
+      else
+        fetchurl attrs;
+
+  # Create the final "sources" from the config
+  mkSources = config:
+    mapAttrs (
+      name: spec:
+        if builtins.hasAttr "outPath" spec
+        then abort
+          "The values in sources.json should not have an 'outPath' attribute"
+        else
+          spec // { outPath = replace name (fetch config.pkgs name spec); }
+    ) config.sources;
+
+  # The "config" used by the fetchers
+  mkConfig =
+    { sourcesFile ? if builtins.pathExists ./sources.json then ./sources.json else null
+    , sources ? if isNull sourcesFile then {} else builtins.fromJSON (builtins.readFile sourcesFile)
+    , system ? builtins.currentSystem
+    , pkgs ? mkPkgs sources system
+    }: rec {
+      # The sources, i.e. the attribute set of spec name to spec
+      inherit sources;
+
+      # The "pkgs" (evaluated nixpkgs) to use for e.g. non-builtin fetchers
+      inherit pkgs;
+    };
+
+in
+mkSources (mkConfig {}) // { __functor = _: settings: mkSources (mkConfig settings); }

apps/kassandra/obelisk-shell.nix

@@ -0,0 +1 @@
+(import ./. { }).shells.ghc

apps/kassandra/release.nix

@@ -0,0 +1,19 @@
+{ pkgs ? import (import nix/sources.nix).nixpkgs { } }:
+let
+  haskellPackages = pkgs.haskellPackages.extend (
+    self: super: {
+      kassandra = self.callCabal2nix "kassandra" ./kassandra { };
+      standalone = self.callCabal2nix "standalone" ./standalone { };
+    }
+  );
+  reflex-platform = import ./. { };
+in
+{
+  lib = haskellPackages.kassandra;
+  app = haskellPackages.standalone;
+  server = reflex-platform.exe;
+  android = pkgs.runCommand "kassandra-android-apk" { } ''
+    mkdir -p $out
+    cp ${reflex-platform.android.frontend}/android-app-release-unsigned.apk $out/de.maralorn.kassandra_${import ./code.nix}.apk
+  '';
+}

apps/kassandra/shell.nix

@@ -0,0 +1,5 @@
+{ pkgs ? import (import nix/sources.nix).nixpkgs { } }: let
+  outputs = import ./release.nix { inherit pkgs; };
+in pkgs.haskellPackages.shellFor {
+  packages = (_: [outputs.lib outputs.app]);
+}

apps/kassandra/standalone/CHANGELOG.md

@@ -0,0 +1,5 @@
+# Revision history for frontend
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.

apps/kassandra/standalone/LICENSE

@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU Affero General Public License is a free, copyleft license for
+software and other kinds of works, specifically designed to ensure
+cooperation with the community in the case of network server software.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+our General Public Licenses are intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+  Developers that use our General Public Licenses protect your rights
+with two steps: (1) assert copyright on the software, and (2) offer
+you this License which gives you legal permission to copy, distribute
+and/or modify the software.
+
+  A secondary benefit of defending all users' freedom is that
+improvements made in alternate versions of the program, if they
+receive widespread use, become available for other developers to
+incorporate.  Many developers of free software are heartened and
+encouraged by the resulting cooperation.  However, in the case of
+software used on network servers, this result may fail to come about.
+The GNU General Public License permits making a modified version and
+letting the public access it on a server without ever releasing its
+source code to the public.
+
+  The GNU Affero General Public License is designed specifically to
+ensure that, in such cases, the modified source code becomes available
+to the community.  It requires the operator of a network server to
+provide the source code of the modified version running there to the
+users of that server.  Therefore, public use of a modified version, on
+a publicly accessible server, gives the public access to the source
+code of the modified version.
+
+  An older license, called the Affero General Public License and
+published by Affero, was designed to accomplish similar goals.  This is
+a different license, not a version of the Affero GPL, but Affero has
+released a new version of the Affero GPL which permits relicensing under
+this license.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                       TERMS AND CONDITIONS
+
+  0. Definitions.
+
+  "This License" refers to version 3 of the GNU Affero General Public License.
+
+  "Copyright" also means copyright-like laws that apply to other kinds of
+works, such as semiconductor masks.
+
+  "The Program" refers to any copyrightable work licensed under this
+License.  Each licensee is addressed as "you".  "Licensees" and
+"recipients" may be individuals or organizations.
+
+  To "modify" a work means to copy from or adapt all or part of the work
+in a fashion requiring copyright permission, other than the making of an
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+  A "covered work" means either the unmodified Program or a work based
+on the Program.
+
+  To "propagate" a work means to do anything with it that, without
+permission, would make you directly or secondarily liable for
+infringement under applicable copyright law, except executing it on a
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+
+  To "convey" a work means any kind of propagation that enables other
+parties to make or receive copies.  Mere interaction with a user through
+a computer network, with no transfer of a copy, is not conveying.
+
+  An interactive user interface displays "Appropriate Legal Notices"
+to the extent that it includes a convenient and prominently visible
+feature that (1) displays an appropriate copyright notice, and (2)
+tells the user that there is no warranty for the work (except to the
+extent that warranties are provided), that licensees may convey the
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+  The "source code" for a work means the preferred form of the work
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+convey, without conditions so long as your license otherwise remains
+in force.  You may convey covered works to others for the sole purpose
+of having them make modifications exclusively for you, or provide you
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+similar laws prohibiting or restricting circumvention of such
+measures.
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+circumvention of technological measures to the extent such circumvention
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+  You may convey verbatim copies of the Program's source code as you
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+  7. Additional Terms.
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+  "Additional permissions" are terms that supplement the terms of this
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apps/kassandra/standalone/src-bin/main.hs

@@ -0,0 +1,6 @@
+module Main (main) where
+
+import Kassandra.Standalone (standalone)
+
+main :: IO ()
+main = standalone

apps/kassandra/standalone/src/Kassandra/Backend/Calendar.hs

@@ -0,0 +1,329 @@
+module Kassandra.Backend.Calendar (
+  getEvents,
+  newCache,
+  Cache (..),
+  setList,
+  loadCache,
+  saveCache,
+) where
+
+import qualified Control.Concurrent.STM as STM
+import qualified Data.Aeson as JSON
+import qualified Data.ByteString.Lazy as LBS
+import Data.Default (Default (def))
+import qualified Data.Map as Map
+import qualified Data.Set as Set
+import qualified Data.Text as Text
+import Data.Time (ZonedTime (ZonedTime), addDays, getCurrentTime, nominalDay, utc)
+import Data.Time.Zones (
+  TZ,
+  loadLocalTZ,
+  loadTZFromDB,
+  localTimeToUTCTZ,
+  timeZoneForUTCTime,
+ )
+import qualified StmContainers.Map as STM
+import Streamly (IsStream, SerialT, async, asyncly, maxThreads)
+import qualified Streamly.Prelude as S
+import System.Directory (
+  XdgDirectory (XdgCache),
+  createDirectoryIfMissing,
+  getModificationTime,
+  getXdgDirectory,
+  setModificationTime,
+ )
+import System.FilePath (dropFileName, (</>))
+import System.FilePattern.Directory (getDirectoryFiles)
+import Text.ICalendar (
+  DTEnd (DTEndDateTime, dtEndDateValue),
+  DTStart (DTStartDateTime, dtStartDateValue),
+  Date (dateValue),
+  DateTime (FloatingDateTime, UTCDateTime, ZonedDateTime),
+  Description (descriptionValue),
+  Location (locationValue),
+  OtherProperty (OtherProperty, otherName, otherValue),
+  Summary (summaryValue),
+  UID (uidValue),
+  VCalendar (vcEvents),
+  VEvent (
+    veDTEndDuration,
+    veDTStart,
+    veDescription,
+    veLocation,
+    veOther,
+    veSummary,
+    veUID
+  ),
+  parseICalendarFile,
+  printICalendar,
+ )
+
+import Control.Exception (onException)
+import Data.Aeson (decodeStrict', encode)
+import qualified DeferredFolds.UnfoldlM as UnfoldlM
+import Kassandra.Calendar (
+  CalendarEvent (..),
+  CalendarList (CalendarList),
+  EventTime (AllDayEvent, SimpleEvent),
+  TZTime (TZTime),
+  tzTimeToUTC,
+  zonedDay,
+ )
+import Kassandra.Debug (Severity (..), log)
+import qualified Streamly.Data.Fold as FL
+import Streamly.External.ByteString (fromArray, toArray)
+import qualified Streamly.FileSystem.Handle as FS
+import qualified Streamly.Internal.FileSystem.File as FSFile
+import Streamly.Memory.Array as Mem (fromList)
+import Streamly.Internal.Data.Array.Stream.Foreign (splitOn)
+
+dirName :: FilePath
+dirName = "/home/maralorn/.calendars/"
+
+data FileInfo = FileInfo
+  { lastRead :: UTCTime
+  , events :: Seq CalendarEvent
+  }
+  deriving stock (Show, Generic)
+  deriving anyclass (ToJSON, FromJSON)
+
+loadCache :: Cache -> IO ()
+loadCache cache = do
+  dir <- getCacheDir
+  let a =
+        S.drain $
+          readJSONStream (cache ^. #icsCache) (dir </> "fileinfo.cache")
+            `async` readJSONStream (cache ^. #uidCache) (dir </> "uid.cache")
+  catch a \(e :: IOException) -> log Warning [i|Error loading calendar Cache:#{e}|]
+  log Debug "Cache Loaded"
+
+readJSONStream :: (IsStream t, Eq k, Hashable k, MonadIO (t IO), FromJSON k, FromJSON v) => STM.Map k v -> FilePath -> t IO ()
+readJSONStream stmMap fileName =
+  FSFile.withFile fileName ReadMode $
+    S.fold
+      (foldSTMMap stmMap)
+      . asyncly
+      . S.mapMaybe (decodeStrict' . fromArray)
+      . splitOn 10
+      . S.unfold FS.readChunks
+
+saveCache :: Cache -> IO ()
+saveCache cache = do
+  dir <- getCacheDir
+  createDirectoryIfMissing True dir
+  let a =
+        S.drain $
+          writeJSONStream (cache ^. #icsCache) (dir </> "fileinfo.cache")
+            `async` writeJSONStream (cache ^. #uidCache) (dir </> "uid.cache")
+  catch a \(e :: IOException) -> log Warning [i|Error writing calendar Cache:#{e}|]
+  log Debug "Saved Cache"
+
+writeJSONStream :: (IsStream t, MonadIO (t IO), ToJSON k, ToJSON v) => STM.Map k v -> FilePath -> t IO ()
+writeJSONStream stmMap fileName =
+  FSFile.withFile fileName WriteMode \handle ->
+    liftIO $
+      S.fold (FS.writeChunks handle)
+        . asyncly
+        . S.intersperse (Mem.fromList [10])
+        . fmap (toArray . toStrict . encode)
+        $ streamSTMMap stmMap
+
+streamSTMMap :: forall t k v. (MonadIO (t IO), IsStream t) => STM.Map k v -> t IO (k, v)
+streamSTMMap = join . atomically . UnfoldlM.foldlM' (\x y -> pure $ S.cons y x) S.nil . STM.unfoldlM
+
+getCacheDir :: IO FilePath
+getCacheDir = getXdgDirectory XdgCache "kassandra"
+
+foldSTMMap :: forall m k v. (Eq k, Hashable k, MonadIO m) => STM.Map k v -> FL.Fold m (k, v) ()
+foldSTMMap cache = FL.foldMapM (\(k, v) -> atomically $ STM.insert v k cache)
+
+type ICSCache = STM.Map FilePath FileInfo
+type UIDCache = STM.Map Text FilePath
+type TZCache = STM.Map (Maybe Text) (Maybe (Text, TZ))
+
+data Cache = Cache
+  { icsCache :: ICSCache
+  , tzCache :: TZCache
+  , uidCache :: UIDCache
+  } deriving (Generic)
+
+newCache :: IO Cache
+newCache = atomically $ Cache <$> STM.new <*> STM.new <*> STM.new
+
+makeLabels ''Cache
+
+foldToSeq :: Monad m => SerialT m a -> m (Seq a)
+foldToSeq = S.foldl' (|>) mempty
+
+setList :: Cache -> Text -> CalendarList -> IO ()
+setList cache uid list = do
+  cachedFilename <- atomically (STM.lookup uid (cache ^. #uidCache))
+  cachedFilename & maybe
+    (log Error [i|Missing uid #{uid} in UIDCache.|])
+    \filename -> do
+      calendars <- foldToSeq (readCalendars filename)
+      insertList calendars & maybe
+        (log Error [i|Did not find Event with uid #{uid} in #{filename}.|])
+        \newCalendars -> do
+          withFile filename WriteMode \fileHandle -> do
+            forM_ newCalendars (LBS.hPut fileHandle . printICalendar def)
+      now <- getCurrentTime
+      setModificationTime (dropFileName filename) now
+ where
+  insertList :: Traversable m => m VCalendar -> Maybe (m VCalendar)
+  insertList cals = if modified then Just ret else Nothing
+   where
+    (ret, modified) = runState (insertListS cals) False
+  insertListS :: Traversable m => m VCalendar -> State Bool (m VCalendar)
+  insertListS = mapM \calendar -> do
+    newEvents <- forM (vcEvents calendar) \event ->
+      if uidValue (veUID event) == toLazy uid
+        then
+          event
+            { veOther =
+                Set.insert (OtherProperty tasksFieldName (maskICSText $ JSON.encode list) def)
+                  . Set.filter (not . isTasksOther)
+                  . veOther
+                  $ event
+            }
+            <$ put True
+        else pure event
+    pure calendar{vcEvents = newEvents}
+
+maskICSText :: LByteString -> LByteString
+maskICSText = LBS.concatMap \case
+  59 -> "\\;"
+  10 -> "\\n"
+  44 -> "\\,"
+  92 -> "\\\\"
+  c -> one c
+
+unmaskICSText :: LByteString -> LByteString
+unmaskICSText = maybe "" (uncurry f) . LBS.uncons
+ where
+  f 92 rest = maybe "" (uncurry w) (LBS.uncons rest)
+  f x rest = one x <> unmaskICSText rest
+  w 92 rest = "\\" <> unmaskICSText rest
+  w 110 rest = "\n" <> unmaskICSText rest
+  w 44 rest = "," <> unmaskICSText rest
+  w 59 rest = ";" <> unmaskICSText rest
+  w _ rest = unmaskICSText rest
+
+tasksFieldName :: IsString t => t
+tasksFieldName = "X-KASSANDRA-TASKS"
+
+isTasksOther :: OtherProperty -> Bool
+isTasksOther = (== tasksFieldName) . otherName
+
+getEvents :: (MonadIO (stream IO), IsStream stream) => Cache -> stream IO CalendarEvent
+getEvents cache = do
+  now <- liftIO getZonedTime
+  let calendarFiles = (dirName </>) <$> (S.fromList =<< liftIO (getDirectoryFiles dirName ["**/*.ics"]))
+      extractEvents = getWithCache cache (zonedTimeToUTC now)
+      filterRelevant = S.filter (onlyNextWeek now)
+  maxThreads 500 . filterRelevant $ extractEvents =<< calendarFiles
+
+getWithCache :: (MonadIO (stream IO), IsStream stream) => Cache -> UTCTime -> FilePath -> stream IO CalendarEvent
+getWithCache cache now fileName =
+  S.fromFoldable =<< liftIO do
+    infoMay <- atomically $ STM.lookup fileName (cache ^. #icsCache)
+    let update = do
+          newEvents <- foldToSeq (readEvents cache fileName)
+          atomically $ STM.insert (FileInfo now newEvents) fileName (cache ^. #icsCache)
+          pure newEvents
+    infoMay & maybe update \FileInfo{lastRead, events} -> do
+      modTime <- getModificationTime fileName
+      if lastRead >= modTime then pure events else update
+
+readCalendars :: (MonadIO (stream IO), IsStream stream) => FilePath -> stream IO VCalendar
+readCalendars path =
+  S.fromList
+    =<< liftIO
+      ( parseICalendarFile def path >>= \case
+          Right (calendarsInFile, fmap toText -> _warnings) -> do
+            mapM_ (log Debug) _warnings
+            pure calendarsInFile
+          Left _parseError -> do
+            log Debug (toText _parseError)
+            pure mempty
+      )
+
+readEvents :: (MonadIO (stream IO), IsStream stream) => Cache -> FilePath -> stream IO CalendarEvent
+readEvents cache path = do
+  calendar <- readCalendars path
+  let uids = toStrict . fst <$> (Map.keys . vcEvents) calendar
+  atomically $ forM_ uids \uid -> STM.insert path uid (cache ^. #uidCache)
+  translateCalendar cache (tryExtractBaseDir (toText path)) calendar
+
+tryExtractBaseDir :: Text -> Text
+tryExtractBaseDir name = fromMaybe name . (viaNonEmpty last <=< viaNonEmpty init) . Text.splitOn "/" $ name
+
+onlyNextWeek :: ZonedTime -> CalendarEvent -> Bool
+onlyNextWeek (zonedTimeToUTC -> now) CalendarEvent{time}
+  | SimpleEvent (tzTimeToUTC -> start) (tzTimeToUTC -> end) <- time = end >= now && start <= addUTCTime (14 * nominalDay) now
+onlyNextWeek now CalendarEvent{time}
+  | AllDayEvent startDay endDay <- time = endDay >= zonedDay now && startDay <= addDays 14 (zonedDay now)
+onlyNextWeek _ _ = False
+
+translateCalendar :: (Monad (stream IO), IsStream stream) => Cache -> Text -> VCalendar -> stream IO CalendarEvent
+translateCalendar cache calendarName = translateEvent cache calendarName <=< S.fromList . Map.elems . vcEvents
+
+translateEvent :: (Functor (stream IO), IsStream stream) => Cache -> Text -> VEvent -> stream IO CalendarEvent
+translateEvent cache calendarName vEvent =
+  withTime <$> getTimes
+ where
+  withTime time = CalendarEvent{uid, description, todoList, time, calendarName, location, comment}
+   where
+    uid = toStrict (uidValue (veUID vEvent))
+    description = (maybe "" (toStrict . summaryValue) . veSummary) vEvent
+    todoList = find isTasksOther (veOther vEvent) >>= JSON.decode . unmaskICSText . otherValue & fromMaybe (CalendarList mempty mempty)
+    location = toStrict . locationValue <$> veLocation vEvent
+    comment = toStrict . descriptionValue <$> veDescription vEvent
+  -- TODO: This currently misses recurring events and
+  -- events with a duration configured
+  -- Also we are ignoring the timezone delivered with this calendar and taking our own
+  getTimes
+    | Just (DTStartDateTime start _) <- veDTStart vEvent
+      , Just (Left (DTEndDateTime end _)) <- veDTEndDuration vEvent =
+      S.yieldM . liftIO $ SimpleEvent <$> datetimeToTZTime cache start <*> datetimeToTZTime cache end
+    | Just (dateValue . dtStartDateValue -> start) <- veDTStart vEvent
+      , Just (Left (dateValue . dtEndDateValue -> end)) <- veDTEndDuration vEvent =
+      S.yield $ AllDayEvent start (addDays (-1) end)
+    | otherwise = S.nil
+
+datetimeToTZTime :: Cache -> DateTime -> IO TZTime
+datetimeToTZTime cache = \case
+  FloatingDateTime t -> withTZ t Nothing
+  UTCDateTime t -> pure $ TZTime (utcToZonedTime utc t) "UTC"
+  ZonedDateTime t (Just . toStrict -> tzname) -> withTZ t tzname
+ where
+  withTZ :: LocalTime -> Maybe Text -> IO TZTime
+  withTZ t tzname =
+    mkTZTime <$> getTZ (cache ^. #tzCache) tzname <*> pure t
+
+getTZ :: TZCache -> Maybe Text -> IO (Text, TZ)
+getTZ cache tzname = do
+  tzMay <- atomically $ do
+    cached <- STM.lookup tzname cache
+    cached & \case
+      Just (Just tz) -> pure (Just tz) -- Cache hit
+      Just Nothing -> STM.retry -- Another thread is already getting this value, wait for it.
+      Nothing -> STM.insert Nothing tzname cache >> pure Nothing -- We need to get this value
+  ( tzMay & flip maybe pure do
+      newTz <- maybe (("Your Time",) <$> loadLocalTZ) loadTZ tzname
+      atomically $ STM.insert (Just newTz) tzname cache
+      pure newTz
+    )
+    `onException` atomically (STM.delete tzname cache)
+ where
+  loadTZ name =
+    ((name,) <$> loadTZFromDB (toString name)) `catch` \(e :: IOException) -> do
+      log Debug [i|Timezone not found "#{name}" trying next.|]
+      log Debug [i|Timezone lookup error was: #{e}|]
+      getTZ cache (nextName name)
+
+mkTZTime :: (Text, TZ) -> LocalTime -> TZTime
+mkTZTime (tzname, tz) t = TZTime (ZonedTime t (timeZoneForUTCTime tz (localTimeToUTCTZ tz t))) tzname
+
+nextName :: Text -> Maybe Text
+nextName = fmap (Text.intercalate "/") . viaNonEmpty tail . filter (not . Text.null) . Text.splitOn "/"

apps/kassandra/standalone/src/Kassandra/Config/Dhall.hs

@@ -0,0 +1,120 @@
+module Kassandra.Config.Dhall (
+  DhallLoadConfig (..),
+  loadDhallConfig,
+  dhallType,
+) where
+
+import Data.Password.Argon2 (
+  Argon2,
+  PasswordHash (PasswordHash),
+ )
+import qualified Data.UUID as UUID
+import Dhall (
+  Decoder,
+  FromDhall,
+  auto,
+  autoWith,
+  expected,
+  extractError,
+  fromMonadic,
+  input,
+  toMonadic,
+ )
+import qualified Dhall
+import Dhall.Core (pretty)
+import System.Environment ()
+
+import Data.Either.Validation (validationToEither)
+import Kassandra.Config (
+  AccountConfig,
+  DefinitionElement,
+  HabiticaList,
+  HabiticaTask,
+  ListItem,
+  LocalBackend,
+  NamedBackend,
+  NamedListQuery,
+  PasswordConfig,
+  PortConfig,
+  QueryFilter,
+  RemoteBackend,
+  TaskProperty,
+  TaskwarriorOption,
+  TreeOption,
+  UIConfig,
+  UIFeatures,
+  UserConfig,
+  Widget,
+ )
+import System.Path.IO (
+  FsPath (FsPath),
+  doesFileExist,
+  fromFilePath,
+ )
+
+instance FromDhall PasswordConfig
+instance FromDhall (RemoteBackend PasswordConfig)
+instance FromDhall TreeOption
+instance FromDhall HabiticaTask
+instance FromDhall ListItem
+instance FromDhall DefinitionElement
+instance FromDhall TaskProperty
+instance FromDhall QueryFilter
+instance FromDhall HabiticaList
+instance FromDhall Widget
+instance FromDhall UIFeatures
+instance FromDhall UIConfig
+instance FromDhall NamedListQuery
+instance FromDhall PortConfig
+instance FromDhall LocalBackend
+instance FromDhall TaskwarriorOption
+instance FromDhall UserConfig
+instance FromDhall AccountConfig
+instance FromDhall b => FromDhall (NamedBackend b)
+
+postComposeMayDecoder :: Text -> (a -> Maybe b) -> Decoder a -> Decoder b
+postComposeMayDecoder err f dec =
+  dec
+    { Dhall.extract =
+        fromMonadic
+          . (maybe (toMonadic $ extractError err) Right . f <=< toMonadic . Dhall.extract dec)
+    }
+instance FromDhall UUID where
+  autoWith =
+    postComposeMayDecoder "Text was no valid UUID" UUID.fromText . autoWith
+
+instance FromDhall a => FromDhall (NonEmpty a) where
+  autoWith = postComposeMayDecoder "List was empty" nonEmpty . autoWith
+
+instance FromDhall (PasswordHash Argon2) where
+  autoWith = fmap PasswordHash . autoWith
+
+data DhallLoadConfig = DhallLoadConfig
+  { envName :: Text
+  , defaultFile :: Text
+  , defaultConfig :: Text
+  }
+  deriving stock (Show, Eq, Ord)
+
+dhallType :: forall a. FromDhall a => Text
+dhallType = fromRight "" . validationToEither $ pretty <$> expected (auto @a)
+
+loadDhallConfig :: FromDhall a => DhallLoadConfig -> Maybe Text -> IO a
+loadDhallConfig loadConfig givenConfigFile = do
+  let defFile = defaultFile loadConfig
+      defConf = defaultConfig loadConfig
+  filename <-
+    firstJustM
+      [ pure givenConfigFile
+      , fmap toText <$> lookupEnv (toString $ envName loadConfig)
+      , doesPathExist defFile
+          <&> \doesExist -> if doesExist then Just defFile else Nothing
+      ]
+  input auto $ maybe defConf (\name -> [i|(#{defConf}) // #{name}|]) filename
+
+doesPathExist :: ToString a => a -> IO Bool
+doesPathExist (fromFilePath . toString -> (FsPath path)) = doesFileExist path
+
+firstJustM :: Monad m => [m (Maybe a)] -> m (Maybe a)
+firstJustM [] = pure Nothing
+firstJustM (a : as) = a >>= \x -> if isJust x then pure x else firstJustM as

apps/kassandra/standalone/src/Kassandra/Standalone.hs

@@ -0,0 +1,82 @@
+module Kassandra.Standalone (
+  standalone,
+) where
+
+import Control.Concurrent.STM (TQueue, newTQueueIO)
+import Control.Exception (SomeAsyncException, throwIO)
+import Data.Typeable (typeOf)
+import Kassandra.Config (NamedBackend (NamedBackend, backend, name))
+import Kassandra.Css (cssAsBS)
+import Kassandra.Debug (Severity (..), log, setLogLevel)
+import Kassandra.LocalBackend (LocalBackendRequest)
+import Kassandra.LocalBackendWidget (localBackendWidget)
+import Kassandra.MainWidget (mainWidget)
+import Kassandra.RemoteBackendWidget (CloseEvent (..), remoteBackendWidget)
+import Kassandra.SelectorWidget (backendSelector)
+import Kassandra.Standalone.Config (
+  StandaloneAccount (LocalAccount, RemoteAccount),
+  backends,
+  dhallTypes,
+  readConfig,
+ )
+import Kassandra.Standalone.State (localBackendProvider)
+import Kassandra.State (StateProvider)
+import Kassandra.Types (WidgetJSM)
+import Kassandra.Util (defDynDyn)
+import qualified Reflex as R
+import qualified Reflex.Dom as D
+import Relude.Extra.Newtype (wrap)
+import Say (say)
+import System.Exit (ExitCode (ExitFailure))
+import System.Posix.Process (exitImmediately)
+
+-- | This function works around the fact that a reflex mainWidget does not exit when it catches an Async Exception.
+exitImmediatelyOnLocalException :: IO a -> IO a
+exitImmediatelyOnLocalException m = catch m catcher
+ where
+  catcher outer@(SomeException inner) = do
+    when (isNothing (fromException outer :: Maybe SomeAsyncException)) do
+      log Error [i|BackendProviderCrashed with error: #{inner} with type #{typeOf inner}|]
+      exitImmediately (ExitFailure 1)
+    throwIO inner
+
+standalone :: IO ()
+standalone = do
+  args <- getArgs
+  when (args == ["print-types"]) do
+    say dhallTypes
+    exitSuccess
+  hSetBuffering Prelude.stdout NoBuffering
+  setLogLevel $ Just Info
+  log Info "Started kassandra"
+  log Debug "Loading Config"
+  config <- readConfig Nothing
+  print config
+  log Debug "Loaded Config"
+  requestQueue <- newTQueueIO
+  race_ (exitImmediatelyOnLocalException (localBackendProvider requestQueue)) do
+    log Info "Hanging in front of main widget"
+    D.mainWidgetWithCss cssAsBS $ do
+      log Info "Entered main widget"
+      -- TODO: Use Config from stateProvider here
+      D.dyn_ . (maybe pass mainWidget <$>)
+        =<< standaloneWidget requestQueue
+        =<< backendSelector (backends config)
+
+standaloneWidget ::
+  WidgetJSM t m =>
+  TQueue LocalBackendRequest ->
+  R.Dynamic t (NamedBackend StandaloneAccount) ->
+  m (R.Dynamic t (Maybe (StateProvider t m)))
+standaloneWidget requestQueue accountDyn =
+  defDynDyn (R.constDyn Nothing) $
+    accountDyn
+      <&> \NamedBackend{name, backend} -> case backend of
+        RemoteAccount remoteAccount ->
+          remoteBackendWidget
+            (wrap $ void $ R.updated accountDyn)
+            remoteAccount
+        LocalAccount localAccount ->
+          localBackendWidget
+            requestQueue
+            NamedBackend{name, backend = localAccount}

apps/kassandra/standalone/src/Kassandra/Standalone/Config.hs

@@ -0,0 +1,117 @@
+{-# LANGUAGE DerivingStrategies #-}
+
+module Kassandra.Standalone.Config (
+  readConfig,
+  StandaloneConfig,
+  StandaloneAccount (LocalAccount, RemoteAccount),
+  BackendConfig (..),
+  backends,
+ dhallTypes
+) where
+
+import Dhall (FromDhall)
+import Kassandra.Config (
+  Dict,
+  AccountConfig,
+  DefinitionElement,
+  ListQuery,
+  LocalBackend,
+  NamedBackend,
+  NamedListQuery,
+  PasswordConfig,
+  PortConfig,
+  RemoteBackend,
+  TaskwarriorOption,
+  TreeOption,
+  UserConfig,
+  Widget, ListItem
+ )
+import Kassandra.Config.Dhall (
+  DhallLoadConfig (..),
+  dhallType,
+  loadDhallConfig,
+ )
+
+newtype StandaloneConfig = Config
+  { backends :: NonEmpty (NamedBackend StandaloneAccount)
+  }
+  deriving stock (Show, Eq, Ord, Generic)
+  deriving anyclass (FromDhall)
+
+data StandaloneAccount = RemoteAccount {backend :: Maybe (RemoteBackend PasswordConfig)} | LocalAccount {userConfig :: UserConfig}
+  deriving stock (Show, Eq, Ord, Generic)
+  deriving anyclass (FromDhall)
+
+data BackendConfig = BackendConfig
+  { users :: Dict AccountConfig
+  }
+  deriving (Show, Eq, Generic, FromDhall)
+
+dhallTypes :: Text
+dhallTypes =
+  [i|{
+#{assignments}
+}|]
+ where
+  types :: [(String, Text)]
+  types =
+    [ ("StandaloneAccount", dhallType @StandaloneAccount)
+    , ("BackendConfig", dhallType @BackendConfig)
+    , ("Widget", dhallType @Widget)
+    , ("NamedListQuery", dhallType @NamedListQuery)
+    , ("LocalBackend", dhallType @LocalBackend)
+    , ("TreeOption", dhallType @TreeOption)
+    , ("PortConfig", dhallType @PortConfig)
+    , ("TaskwarriorOption", dhallType @TaskwarriorOption)
+    , ("StandaloneConfig", dhallType @StandaloneConfig)
+    , ("PasswordConfig", dhallType @PasswordConfig)
+    , ("AccountConfig", dhallType @AccountConfig)
+    , ("DefinitionElement", dhallType @DefinitionElement)
+    , ("ListQuery", dhallType @ListQuery)
+    , ("RemoteBackend", dhallType @(RemoteBackend PasswordConfig))
+    , ("ListItem", dhallType @ListItem)
+    ]
+  assignments =
+    intercalate ",\n" $ (\(name, value) -> [i|#{name} = #{value}|]) <$> types
+
+readConfig :: Maybe Text -> IO StandaloneConfig
+readConfig =
+  loadDhallConfig
+    DhallLoadConfig
+      { envName = "KASSANDRA_CONFIG"
+      , defaultFile = "~/.config/kassandra/config.dhall"
+      , defaultConfig =
+          [i|
+    let
+      types = #{dhallTypes} in
+    {
+      backends = [
+        {
+          name = "Default local backend",
+          backend = types.StandaloneAccount.LocalAccount {
+            userConfig = {
+              localBackend = types.LocalBackend.TaskwarriorBackend {
+                createHooksOnStart = True,
+                hookListenPort = types.PortConfig.PortRange { min = 40000, max = 50000 },
+                hookSuffix = "kassandra",
+                removeHooksOnExit = True,
+                taskBin = None Text,
+                taskConfig = [] : List types.TaskwarriorOption,
+                taskDataPath = None Text,
+                taskRcPath = None Text
+              },
+              uiConfig = {
+                configuredLists = [] : List types.NamedListQuery ,
+                uiFeatures = {
+                  sortInTag = False,
+                  treeOption = types.TreeOption.NoTree
+                },
+                viewList = [ types.Widget.SearchWidget ]
+              }
+            }
+          }
+        }
+      ]
+    }
+|]
+      }

apps/kassandra/standalone/src/Kassandra/Standalone/State.hs

@@ -0,0 +1,156 @@
+{-# LANGUAGE BlockArguments #-}
+
+module Kassandra.Standalone.State (
+  localBackendProvider,
+) where
+
+import Control.Concurrent.STM (TQueue, readTQueue)
+import Control.Concurrent.STM.TVar (stateTVar)
+import Control.Monad.STM (retry)
+import qualified Data.Aeson as Aeson
+import qualified Data.Map as Map
+import qualified Data.Sequence as Seq
+import qualified Data.Sequence.NonEmpty as NESeq
+import qualified Network.Simple.TCP as Net
+import Say (say, sayErr)
+import Streamly (
+  SerialT,
+  asyncly,
+  maxThreads,
+  parallel,
+  parallely,
+  serial,
+ )
+import qualified Streamly.Prelude as S
+import Taskwarrior.IO (getTasks, saveTasks)
+
+import Kassandra.Api (
+  SocketMessage (..),
+  SocketRequest (..),
+ )
+import Kassandra.Backend.Calendar (
+  Cache,
+  getEvents,
+  loadCache,
+  newCache,
+  saveCache,
+  setList,
+ )
+import Kassandra.Config (LocalBackend, UserConfig (..))
+import Kassandra.Debug (Severity (Debug), log)
+import Kassandra.LocalBackend (
+  LocalBackendRequest (LocalBackendRequest),
+  alive,
+  requestQueue,
+  responseCallback,
+  userConfig,
+ )
+
+foldToSeq :: Monad m => SerialT m a -> m (Seq a)
+foldToSeq = S.foldl' (|>) mempty
+
+waitTillFalse :: MonadIO m => TVar Bool -> m ()
+waitTillFalse boolTvar = (atomically . whenM (readTVar boolTvar)) retry
+concurrentWhileTrue :: TVar Bool -> IO a -> IO ()
+concurrentWhileTrue boolTvar action = race_ action (waitTillFalse boolTvar)
+lookupTMap :: (Ord k, MonadIO f) => k -> TVar (Map k a) -> f (Maybe a)
+lookupTMap key tvarMap = Map.lookup key <$> readTVarIO tvarMap
+insertOrAddTMap :: Ord k => k -> e -> TVar (Map k (Seq e)) -> STM Bool
+insertOrAddTMap key entry tvarMap =
+  stateTVar tvarMap \theMap ->
+    second (\x -> Map.insert key x theMap) $
+      Map.lookup key theMap & \case
+        Just listeners -> (False, listeners |> entry)
+        Nothing -> (True, one entry)
+
+type ClientMap = Map LocalBackend (Seq (TVar Bool, SocketMessage -> IO ()))
+
+localBackendProvider :: TQueue LocalBackendRequest -> IO ()
+localBackendProvider requestQueue = newTVarIO mempty >>= handleRequests requestQueue
+
+handleRequests :: TQueue LocalBackendRequest -> TVar ClientMap -> IO ()
+handleRequests requestQueue mapVar = do
+  cache <- newCache
+  let go = atomically (readTQueue requestQueue) >>= \req -> concurrently_ (handleRequest req cache mapVar) go
+  S.drain $
+    ( liftIO (loadCache cache)
+        `serial` (asyncly . maxThreads 100 . void . getEvents) cache
+        `serial` liftIO (saveCache cache)
+    )
+      `parallel` liftIO go
+
+monitorCallback :: LocalBackend -> TVar ClientMap -> NonEmpty Task -> IO ()
+monitorCallback key mapVar tasks =
+  whenJustM (lookupTMap key mapVar) $
+    mapM_ (($ TaskUpdates (NESeq.fromList tasks)) . snd)
+
+handleRequest :: LocalBackendRequest -> Cache -> TVar ClientMap -> IO ()
+handleRequest req cache mapVar =
+  S.drain
+    . parallely
+    . S.fromFoldableM
+    $ [ do handleRequestsWhileAlive req cache; removeClientFromMap req mapVar
+      , launchOrAttachMonitor req mapVar
+      , responseCallback req ConnectionEstablished
+      , say "Client registered on backend"
+      ]
+
+removeClientFromMap :: MonadIO m => LocalBackendRequest -> TVar ClientMap -> m ()
+removeClientFromMap req mapVar = atomically (modifyTVar' mapVar updateMap)
+ where
+  key = localBackend . userConfig $ req
+  filterClients = Seq.filter ((/= alive req) . fst)
+  setEntry newEntry clientMap
+    | null newEntry = Map.delete key clientMap
+    | otherwise = Map.insert key newEntry clientMap
+  updateMap clientMap =
+    Map.lookup key clientMap & \case
+      Just clients -> setEntry (filterClients clients) clientMap
+      Nothing -> clientMap
+
+launchOrAttachMonitor :: LocalBackendRequest -> TVar ClientMap -> IO ()
+launchOrAttachMonitor LocalBackendRequest{userConfig, alive, responseCallback} mapVar =
+  whenM (atomically $ insertOrAddTMap localBackend entry mapVar) $
+    do
+      whileClientsNotEmpty (taskMonitor localBackend (monitorCallback localBackend mapVar))
+      say "Stopped listening for changes"
+ where
+  UserConfig{localBackend} = userConfig
+  entry = (alive, responseCallback)
+  waitForClientsEmpty = atomically . whenJustM (Map.lookup localBackend <$> readTVar mapVar) . const $ retry
+  whileClientsNotEmpty action = race_ action waitForClientsEmpty
+
+-- TODO: Use backend config
+
+handleRequestsWhileAlive :: LocalBackendRequest -> Cache -> IO ()
+handleRequestsWhileAlive LocalBackendRequest{userConfig, alive, responseCallback, requestQueue} cache =
+  concurrentWhileTrue alive go
+ where
+  handler = \case
+    UIConfigRequest -> (responseCallback . UIConfigResponse . uiConfig) userConfig
+    AllTasks -> whenNotNullM (getTasks []) (responseCallback . TaskUpdates . NESeq.fromList)
+    ChangeTasks tasks -> (saveTasks . toList) tasks
+    SetCalendarList uid list -> do
+      setList cache uid list
+      sendCalendarEvents
+    CalenderRequest -> sendCalendarEvents
+  go = do
+    nextRequest <- atomically (readTQueue requestQueue)
+    concurrently_ (handler nextRequest) go
+  sendCalendarEvents = do
+    events <- foldToSeq (getEvents cache)
+    log Debug [i|Sending #{Seq.length events} events|]
+    responseCallback . CalendarEvents $ events
+
+taskMonitor :: LocalBackend -> (NonEmpty Task -> IO ()) -> IO ()
+taskMonitor _ newTasksCallBack = do
+  say "Listening for changed or new tasks on 127.0.0.1:6545."
+  Net.serve (Net.Host "127.0.0.1") "6545" $ \(socket, _) -> Net.recv socket 4096 >>= unwrapChanges
+ where
+  unwrapChanges = maybe (sayErr "Unsuccessful connection attempt.") handleChanges
+  handleChanges changes =
+    either
+      (\err -> sayErr [i|Couldn‘t decode #{changes} as Task: #{err}|])
+      (newTasksCallBack . one)
+      . Aeson.eitherDecodeStrict @Task
+      $ changes

apps/kassandra/standalone/standalone.cabal

@@ -0,0 +1,112 @@
+cabal-version:      2.4
+name:               standalone
+version:            0.1.0.0
+
+-- BEGIN dhall generated common configuration
+-- generate with: dhall text --file common-config.dhall
+license-file:       LICENSE
+author:             Malte Brandy
+maintainer:         malte.brandy@maralorn.de
+build-type:         Simple
+extra-source-files: CHANGELOG.md
+
+common common-config
+  default-extensions:
+    AllowAmbiguousTypes
+    BlockArguments
+    ConstraintKinds
+    DataKinds
+    DeriveAnyClass
+    DeriveGeneric
+    DerivingStrategies
+    DuplicateRecordFields
+    EmptyCase
+    FlexibleContexts
+    FlexibleInstances
+    GADTs
+    LambdaCase
+    MultiParamTypeClasses
+    NamedFieldPuns
+    OverloadedLabels
+    OverloadedStrings
+    PartialTypeSignatures
+    PatternGuards
+    PatternSynonyms
+    QuasiQuotes
+    RankNTypes
+    RecursiveDo
+    ScopedTypeVariables
+    StandaloneDeriving
+    StrictData
+    TemplateHaskell
+    TupleSections
+    TypeApplications
+    TypeFamilies
+    UndecidableInstances
+    ViewPatterns
+
+  ghc-options:
+    -Wall -Wcompat -Wno-orphans -Wincomplete-uni-patterns
+    -Wincomplete-record-updates -Wmissing-export-lists -Widentities
+    -Wredundant-constraints -Wmissing-home-modules
+
+  mixins:             base hiding (Prelude)
+  default-language:   Haskell2010
+
+-- END dhall generated common configuration
+
+
+library
+  import:          common-config
+  hs-source-dirs:  src
+  exposed-modules:
+    Kassandra.Backend.Calendar
+    Kassandra.Config.Dhall
+    Kassandra.Standalone
+    Kassandra.Standalone.Config
+    Kassandra.Standalone.State
+
+  build-depends:
+    , aeson
+    , base
+    , bytestring
+    , containers
+    , data-default
+    , deferred-folds
+    , dhall
+    , directory
+    , either
+    , filepath
+    , filepattern
+    , iCalendar               >=0.4
+    , kassandra
+    , network-simple
+    , nonempty-containers
+    , password                >=2.0.1.0
+    , paths
+    , reflex
+    , reflex-dom
+    , relude
+    , say
+    , stm
+    , stm-containers
+    , streamly
+    , streamly-bytestring
+    , taskwarrior
+    , text
+    , time
+    , tz
+    , unix
+    , uuid
+
+  hs-source-dirs:  src
+
+executable kassandra2
+  import:         common-config
+  main-is:        main.hs
+  hs-source-dirs: src-bin
+  build-depends:
+    , base
+    , kassandra
+    , standalone
+  ghc-options:    -threaded

apps/kassandra/weeder.dhall

@@ -0,0 +1 @@
+{ roots = [ "^Standalone.standalone$", "^Main.main$", "^Backend.backend$", "^Frontend.frontend$", "^Prelude.makeLabels$", "^Kassandra.Debug.log", "Kassandra.ReflexUtil" ], type-class-roots = True }