feat: make VCsWatcher, a watch channel of VCs

src/main.rs

@@ -1,7 +1,6 @@
 use clap::Parser;
 use fomo_reducer::{
-    BotDataManager, CommandRouter, GuildVoiceChannelToTextChannel, State, Storage, UserDataManager,
-    all_commands, command, initialize_vcs, update_vcs,
+    BotDataManager, CommandRouter, GuildVoiceChannelToTextChannel, State, Storage, UserDataManager, VCsWatcher, all_commands, command, initialize_vcs, update_vcs
 };
 use secrecy::{ExposeSecret, SecretString};
 use snafu::{OptionExt, ResultExt, Snafu};
@@ -316,7 +315,7 @@ async fn main() -> Result<(), MainError> {
 
     let discord_client = Arc::new(discord_client);
     let songbird = Arc::new(songbird);
-    let vcs = Arc::new(vcs);
+    let vcs_watcher = VCsWatcher::new(vcs);
 
     let bot_data = bot_data.into_inner();
     let recording_data = recording_data.into_inner();
@@ -358,7 +357,7 @@ async fn main() -> Result<(), MainError> {
         recording_data,
         songbird,
         user_data_manager,
-        vcs,
+        vcs_watcher,
     };
 
     if let Some(discord_status) = discord_status {
@@ -455,7 +454,7 @@ async fn handle_event(command_router: Arc<CommandRouter>, state: State, event: E
 
     match event {
         Event::VoiceStateUpdate(voice_state_update) => {
-            update_vcs(&voice_state_update, &state.vcs);
+            state.vcs_watcher.send_modify(|vcs| update_vcs(&voice_state_update, vcs));
         }
         Event::InteractionCreate(interaction_create) => {
             let InteractionCreate(interaction) = *interaction_create;