Improve registered commands caching

Discord's API is slow in updating and registering new commands, so we set up a runnable to periodically check.

src/main/java/wtf/beatrice/hidekobot/Configuration.java

@@ -37,7 +37,7 @@ public class Configuration
     private static final String botName = "HidekoBot";
     private static final Color botColor = Color.PINK;
 
-    private static final List<Command> registeredCommands = new ArrayList<>();
+    private static List<Command> registeredCommands = new ArrayList<>();
 
     private final static String defaultInviteLink =
             "https://discord.com/api/oauth2/authorize?client_id=%userid%&scope=bot+applications.commands&permissions=8";
@@ -184,7 +184,7 @@ public class Configuration
                 .sorted(Comparator.comparing(Command::getName))
                 .toList();
 
-        registeredCommands.addAll(tempList);
+        registeredCommands = new ArrayList<>(tempList);
     }
 
     /**

src/main/java/wtf/beatrice/hidekobot/HidekoBot.java

@@ -11,6 +11,7 @@ import wtf.beatrice.hidekobot.listeners.ButtonInteractionListener;
 import wtf.beatrice.hidekobot.listeners.MessageListener;
 import wtf.beatrice.hidekobot.listeners.SlashCommandCompleter;
 import wtf.beatrice.hidekobot.listeners.SlashCommandListener;
+import wtf.beatrice.hidekobot.runnables.CommandsUpdateTask;
 import wtf.beatrice.hidekobot.runnables.ExpiredMessageTask;
 import wtf.beatrice.hidekobot.utils.Logger;
 import wtf.beatrice.hidekobot.utils.SlashCommandUtil;
@@ -90,7 +91,7 @@ public class HidekoBot
 
         // update slash commands (delayed)
         final boolean finalForceUpdateCommands = forceUpdateCommands;
-        Executors.newSingleThreadScheduledExecutor().schedule(() ->
+        Executors.newSingleThreadScheduledExecutor().schedule(() -> // todo: try-with-resources
                 SlashCommandUtil.updateSlashCommands(finalForceUpdateCommands), 1, TimeUnit.SECONDS);
 
         // set the bot's status
@@ -114,11 +115,11 @@ public class HidekoBot
         }
 
         // start scheduled runnables
-        ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor();
-        ExpiredMessageTask task = new ExpiredMessageTask();
-        int initDelay = 5;
-        int periodicDelay = 5;
-        scheduler.scheduleAtFixedRate(task, initDelay, periodicDelay, TimeUnit.SECONDS);
+        ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor(); // todo: try-with-resources
+        ExpiredMessageTask expiredMessageTask = new ExpiredMessageTask();
+        scheduler.scheduleAtFixedRate(expiredMessageTask, 5, 5, TimeUnit.SECONDS); //every 5 seconds
+        CommandsUpdateTask commandsUpdateTask = new CommandsUpdateTask();
+        scheduler.scheduleAtFixedRate(commandsUpdateTask, 10, 300, TimeUnit.SECONDS); //every 5 minutes
 
         // register shutdown interrupt signal listener for proper shutdown.
         Signal.handle(new Signal("INT"), signal -> shutdown());

src/main/java/wtf/beatrice/hidekobot/runnables/CommandsUpdateTask.java

@@ -0,0 +1,25 @@
+package wtf.beatrice.hidekobot.runnables;
+
+import net.dv8tion.jda.api.JDA;
+import wtf.beatrice.hidekobot.Configuration;
+import wtf.beatrice.hidekobot.HidekoBot;
+import wtf.beatrice.hidekobot.utils.Logger;
+
+public class CommandsUpdateTask  implements Runnable {
+
+    private final Logger logger;
+
+    public CommandsUpdateTask()
+    {
+        logger = new Logger(getClass());
+    }
+
+    @Override
+    public void run() {
+        if(Configuration.isVerbose()) logger.log("Refreshing commands cache...");
+        JDA instance = HidekoBot.getAPI();
+        if(instance == null) return;
+        Configuration.setRegisteredCommands(instance.retrieveCommands().complete());
+        if(Configuration.isVerbose()) logger.log("Commands cache refreshed!");
+    }
+}

src/main/java/wtf/beatrice/hidekobot/utils/SlashCommandUtil.java

@@ -125,6 +125,9 @@ public class SlashCommandUtil
         }
 
         // cache the registered commands.
+        // note that if this is the first time the bot runs after updating commands,
+        // this will probably still return the previous configuration because the discord api
+        // needs to propagate. this is why we also set up a command updater task (ExpiredMessageTask).
         Configuration.setRegisteredCommands(jdaInstance.retrieveCommands().complete());
     }
 }