Pass default domain via commandline argument

src/main.rs

@@ -1,8 +1,17 @@
 use std::io::{self};
 use std::collections::BTreeMap;
+use std::env;
 
 fn main() {
-    let redirects = parse_alias_to_map();
+    let args: Vec<String> = env::args().collect();
+    if args.len() < 2 {
+        print_help();
+        return;
+    }
+    
+    let default_domain = &args[1];
+
+    let redirects = parse_alias_to_map(default_domain);
     let sieve_script = generate_sieve_script(redirects);
     println!("{}", sieve_script);
 }
@@ -24,7 +33,7 @@ fn generate_sieve_script(redirects: BTreeMap<String, Vec<String>>) -> String {
     script
 }
 
-fn parse_alias_to_map() -> BTreeMap<String, Vec<String>> {
+fn parse_alias_to_map(default_domain : &str) -> BTreeMap<String, Vec<String>> {
     // File must exist in the current path
     let mut redirect_map : BTreeMap<String, Vec<String>> = BTreeMap::new();
     let mut destinations : Vec<String> = Vec::new();
@@ -36,12 +45,12 @@ fn parse_alias_to_map() -> BTreeMap<String, Vec<String>> {
             continue;
         }
         let redirects: Vec<String> = line.split_at(line.find(char::is_whitespace).unwrap_or(0)).1.split(" ")
-            .filter(|address| address.trim().to_string().replace(",","") != "").map(to_mailaddress).collect();
+            .filter(|address| address.trim().to_string().replace(",","") != "").map(|addr| to_mailaddress(addr, default_domain)).collect();
         if redirects.is_empty() {
             continue;
         }
-        destinations.push(to_mailaddress(destination));
-        redirect_map.insert(to_mailaddress(destination), redirects);
+        destinations.push(to_mailaddress(destination, default_domain));
+        redirect_map.insert(to_mailaddress(destination, default_domain), redirects);
     }
     let mut changed = true; 
     while changed {
@@ -64,11 +73,16 @@ fn parse_alias_to_map() -> BTreeMap<String, Vec<String>> {
     redirect_map
 }
 
-fn to_mailaddress(local_part: &str) -> String {
+fn to_mailaddress(local_part: &str, default_domain : &str) -> String {
     let mut addr = local_part.trim().to_string();
     addr = addr.replace(",", "");
     if addr.contains("@") {
         return addr;
     }
-    addr + "@mathebau.de"
+    addr + "@" + default_domain
 }
+
+fn print_help(){
+    print!("Reads a virtual alias file from STDIN and needs a default domain to append to local paths, e.g.
+    cat virt_aliases | ./alias_to_sieve example.com");
+}