use chrono::offset::Utc;
use curl::{easy, easy::Easy2};
use rand::prelude::*;
use ring_compat::signature::ed25519::SigningKey;
use rusqlite::{Connection, DatabaseName};
use tauri::{Manager, State};
use tokio::sync::Mutex;

use crate::server::app_state::AppState;

#[derive(Debug)]
struct Collector(Vec<u8>, Vec<u8>, usize);

impl easy::Handler for Collector {
	fn write(&mut self, data: &[u8]) -> Result<usize, easy::WriteError> {
		self.0.extend_from_slice(data);
		Ok(data.len())
	}

	fn read(&mut self, data: &mut [u8]) -> Result<usize, easy::ReadError> {
		let p = self.2;
		let src: &[u8] = self.1.as_ref();
		let n = usize::min(src.len() - p, data.len());
		data[..n].copy_from_slice(&src[p..(p + n)]);
		self.2 = n + p;
		Ok(n)
	}

	fn seek(&mut self, whence: std::io::SeekFrom) -> easy::SeekResult {
		use std::io::SeekFrom::{Current, End, Start};
		match whence {
			Start(p) => {
				self.2 = p as usize;
				easy::SeekResult::Ok
			}
			End(d) => {
				let p = self.1.len() as i64;
				if p + d < 0 {
					easy::SeekResult::Fail
				} else {
					self.2 = (p + d) as usize;
					easy::SeekResult::Ok
				}
			}
			Current(d) => {
				let p = self.2 as i64;
				if p + d < 0 {
					easy::SeekResult::Fail
				} else {
					self.2 = (p + d) as usize;
					easy::SeekResult::Ok
				}
			}
		}
	}
}

fn data_client(file: &str) -> Result<Easy2<Collector>, ()> {
	let mut client = Easy2::new(Collector(Vec::new(), Vec::new(), 0));
	let url = format!(
		"https://cloud.seebruecke.org/public.php/webdav/data/{}",
		file
	);
	client.url(&url).map_err(|_| ())?;
	client.username(include_str!("cloud_user.txt"))
		.map_err(|_| ())?;
	client.http_auth(easy::Auth::new().auto(true))
		.map_err(|_| ())?;
	client.ssl_cainfo_blob(include_bytes!("isrg-root-x1.pem"))
		.map_err(|_| ())?;
	Ok(client)
}

fn put_client(file: &str, payload: &[u8]) -> Result<Easy2<Collector>, ()> {
	let mut client = data_client(&file)?;
	client.put(true).map_err(|_| ())?;
	client.get_mut().1.extend_from_slice(payload);
	client.in_filesize(payload.len() as u64)
		.map_err(|e| println!("{:?}", e))?;
	client.upload(true).map_err(|e| println!("{:?}", e))?;
	Ok(client)
}

#[tauri::command]
pub async fn pull_data(
	_state: State<'_, Mutex<AppState>>,
) -> Result<String, ()> {
	let mut client = data_client("")?;
	client.custom_request("PROPFIND").map_err(|_| ())?;
	client.perform().map_err(|_| ())?;
	let content = &client.get_ref().0;
	Ok(String::from_utf8_lossy(content).to_string())
}

async fn push_key(id: &u64, key: &SigningKey) -> Result<(), ()> {
	let file = format!("{:016X}.key", id);
	let v_key = key.verifying_key();
	let client = put_client(&file, v_key.as_ref())?;
	let _perf = client.perform().map_err(|e| println!("{:?}", e))?;
	Ok(())
}

fn push_db(id: &u64, db: &Connection, app: tauri::AppHandle) -> Result<(), ()> {
	let filename = format!("{:016X}.sqlite", id);
	let path = app
		.path()
		.resolve(&filename, tauri::path::BaseDirectory::Temp)
		.map_err(|e| println!("{:?}", e))?;
	db.backup(DatabaseName::Main, &path, None)
		.map_err(|e| println!("{:?}", e))?;
	let buf = std::fs::read(&path).map_err(|e| println!("{:?}", e))?;
	let client = put_client(&filename, buf.as_ref())?;
	let _perf = client.perform().map_err(|e| println!("{:?}", e))?;
	Ok(())
}

#[tauri::command]
pub async fn push_data(
	app: tauri::AppHandle,
	state: State<'_, Mutex<AppState>>,
) -> Result<(), ()> {
	let state = state.lock().await;
	push_key(&state.id, &state.key).await?;
	push_db(&state.id, &state.db, app)?;
	Ok(())
}