feat: api v9 and threads (#5570)

Co-authored-by: Noel <icrawltogo@gmail.com>
Co-authored-by: Amish Shah <dev@shah.gg>
Co-authored-by: Vlad Frangu <kingdgrizzle@gmail.com>
Co-authored-by: SynthGhost <60333233+synthghost@users.noreply.github.com>
Co-authored-by: SpaceEEC <24881032+SpaceEEC@users.noreply.github.com>
Co-authored-by: Elliot <elliot@maisl.fr>
Co-authored-by: Antonio Román <kyradiscord@gmail.com>
Co-authored-by: Sugden <28943913+NotSugden@users.noreply.github.com>

src/client/actions/ThreadListSync.js

@@ -0,0 +1,59 @@
+'use strict';
+
+const Action = require('./Action');
+const Collection = require('../../util/Collection');
+const { Events } = require('../../util/Constants');
+
+class ThreadListSyncAction extends Action {
+  handle(data) {
+    const client = this.client;
+
+    const guild = client.guilds.cache.get(data.guild_id);
+    if (!guild) return {};
+
+    if (data.channels_ids) {
+      for (const id of data.channel_ids) {
+        const channel = client.channels.resolve(id);
+        if (channel) this.removeStale(channel);
+      }
+    } else {
+      for (const channel of guild.channels.cache.values()) {
+        this.removeStale(channel);
+      }
+    }
+
+    const syncedThreads = data.threads.reduce((coll, rawThread) => {
+      const thread = client.channels.add(rawThread);
+      return coll.set(thread.id, thread);
+    }, new Collection());
+
+    for (const rawMember of Object.values(data.members)) {
+      // Discord sends the thread id as id in this object
+      const thread = client.channels.cache.get(rawMember.id);
+      if (thread) {
+        thread.members._add(rawMember);
+      }
+    }
+
+    /**
+     * Emitted whenever the client user gains access to a text or news channel that contains threads
+     * @event Client#threadListSync
+     * @param {Collection<Snowflake, ThreadChannel>} threads The threads that were synced
+     */
+    client.emit(Events.THREAD_LIST_SYNC, syncedThreads);
+
+    return {
+      syncedThreads,
+    };
+  }
+
+  removeStale(channel) {
+    channel.threads?.cache.forEach(thread => {
+      if (!thread.archived) {
+        this.client.channels.remove(thread.id);
+      }
+    });
+  }
+}
+
+module.exports = ThreadListSyncAction;