sweep message cache

utils/cache.ts

@@ -1,6 +1,7 @@
 import { Message } from "../structures/message.ts";
 import { Guild } from "../structures/guild.ts";
 import { Channel } from "../structures/channel.ts";
+import { delay } from "https://deno.land/std@0.50.0/async/delay.ts";
 
 export interface CacheData {
   guilds: Map<string, Guild>;
@@ -15,3 +16,43 @@ export const cache: CacheData = {
   messages: new Map(),
   unavailableGuilds: new Map(),
 };
+
+async function cleanMessageCache() {
+  // Find all messages for each channel and if more than 100 we need to remove the oldest messages.
+  const messagesPerChannel = new Map<string, Message[]>();
+
+  for (const message of cache.messages.values()) {
+    if (
+      // If the guild isn't in cache the message is useless to cache
+      (message.guildID && !cache.guilds.has(message.guildID)) ||
+      // If the channel isn't in cache the message is useless in cache
+      !cache.channels.has(message.channelID)
+    ) {
+      cache.messages.delete(message.id);
+    }
+
+    const channel = messagesPerChannel.get(message.channelID);
+    if (!channel) {
+      messagesPerChannel.set(message.channelID, [message]);
+    } else {
+      channel.push(message);
+    }
+  }
+
+  messagesPerChannel.forEach((messages) => {
+    if (messages.length < 100) return;
+
+    // This channel has more than 100 messages in cache. Delete the oldest
+    const sortedMessages = messages.sort((a, b) => b.timestamp - a.timestamp);
+
+    sortedMessages.slice(100).forEach((message) =>
+      cache.messages.delete(message.id)
+    );
+  });
+
+  // Check once per minute
+  await delay(60000);
+  cleanMessageCache();
+}
+
+cleanMessageCache();