autoleave empty voice channels

src/main.rs

@@ -289,8 +289,28 @@ impl EventHandler for Handler {
         old: Option<VoiceState>,
         new: VoiceState,
     ) {
-        if let (Some(guild_id), Some(user_channel)) = (guild_id_opt, new.channel_id) {
+        if let Some(past_state) = old {
-            if old.is_none() {
+            if let (Some(guild_id), None) = (guild_id_opt, new.channel_id) {
+                if let Some(channel_id) = past_state.channel_id {
+                    if let Some(Channel::Guild(channel)) = channel_id.to_channel_cached(&ctx).await
+                    {
+                        if channel.members(&ctx).await.map(|m| m.len()).unwrap_or(0) <= 1 {
+                            let voice_manager_lock = ctx
+                                .data
+                                .read()
+                                .await
+                                .get::<VoiceManager>()
+                                .cloned()
+                                .expect("Could not get VoiceManager from data");
+
+                            let mut voice_manager = voice_manager_lock.lock().await;
+
+                            voice_manager.leave(guild_id);
+                        }
+                    }
+                }
+            }
+        } else if let (Some(guild_id), Some(user_channel)) = (guild_id_opt, new.channel_id) {
             if let Some(guild) = ctx.cache.guild(guild_id).await {
                 let pool = ctx
                     .data
@@ -352,7 +372,6 @@ SELECT name, id, plays, public, server_id, uploader_id
         }
     }
 }
-}
 
 async fn play_audio(
     sound: &mut Sound,