Added new patterns.

Description:
- Added patterns for more generic command substitution.

Signed-off-by: Pavel Kirilin <win10@list.ru>

src/run_modes.rs

@@ -48,17 +48,35 @@ pub fn next_episode(current: usize) -> AppResult<usize> {
     }
 }
 
+fn add_leading_zero(n: usize) -> String {
+    if n < 10 {
+        format!("0{}", n)
+    } else {
+        format!("{}", n)
+    }
+}
+
+fn prepare_command(conf: Config) -> AppResult<String> {
+    let index = conf.current_episode_count;
+    Ok(conf.command
+        .replace("{}", conf.get_current_episode()?.as_str())
+        .replace("{n}", format!("{}", index).as_str())
+        .replace("{n+}", format!("{}", index + 1).as_str())
+        .replace("{zn}", add_leading_zero(index).as_str())
+        .replace("{zn+}", add_leading_zero(index).as_str()))
+}
+
 pub fn play() -> AppResult<()> {
-    let conf = Config::read()?;
+    let mut conf = Config::read()?;
     let mut episode = conf.get_current_episode()?;
     while !episode.is_empty() {
         let mut child = Command::new("sh")
             .arg("-c")
-            .arg(conf.command.replace("{}", episode.as_str()))
+            .arg(prepare_command(conf.clone())?)
             .spawn()?;
         child.wait()?;
         update_episode(next_episode)?;
-        let conf = Config::read()?;
+        conf = Config::read()?;
         episode = conf.get_current_episode()?;
     }
     Ok(())