feat(domain): add feed subscriptions (follow/unfollow) logic

application/domain/feed.js

@@ -0,0 +1,63 @@
+({
+  async follow(userId, roomId) {
+    if (!userId || !roomId) {
+      throw new Error('userId and roomId are required');
+    }
+
+    const room = await domain.chat.getRoom(roomId);
+
+    if (!room) {
+      throw new Error(`Room ${roomId} does not exists`);
+    }
+
+    const userKey = `user:${userId}:subscriptions`;
+    const userRecord = (await db.globalstorage.get(userKey)) || { rooms: [] };
+
+    if (!userRecord.rooms.includes(roomId)) {
+      userRecord.rooms.push(roomId);
+      await db.globalstorage.set(userKey, userRecord);
+    }
+
+    const roomKey = `room:${roomId}:followers`;
+    const roomRecord = (await db.globalstorage.get(roomKey)) || { users: [] };
+
+    if (!roomRecord.users.includes(userId)) {
+      roomRecord.users.push(userId);
+      await db.globalstorage.set(roomKey, roomRecord);
+    }
+
+    return { userId, room: roomId };
+  },
+
+  async unfollow(userId, roomId) {
+    const userKey = `user:${userId}:subscriptions`;
+    const roomKey = `room:${roomId}:followers`;
+
+    const userRecord = await db.globalstorage.get(userKey);
+    const roomRecord = await db.globalstorage.get(roomKey);
+
+    if (userRecord?.rooms) {
+      userRecord.rooms = userRecord.rooms.filter((r) => r !== roomId);
+      await db.globalstorage.set(userKey, userRecord);
+    }
+
+    if (roomRecord?.users) {
+      roomRecord.users = roomRecord.users.filter((u) => u !== userId);
+      await db.globalstorage.set(roomKey, roomRecord);
+    }
+
+    return { userId, room: roomId };
+  },
+
+  async getFollowers(roomId) {
+    const key = `room:${roomId}:followers`;
+    const record = await db.globalstorage.get(key);
+    return record?.users ?? [];
+  },
+
+  async getUserSubscriptions(userId) {
+    const key = `user:${userId}:subscriptions`;
+    const record = await db.globalstorage.get(key);
+    return record?.rooms ?? [];
+  },
+});