Init commit

server/core/lib/live/live-chat-store.ts

@@ -0,0 +1,82 @@
+import { randomUUID } from 'node:crypto'
+
+export type LiveChatMessage = {
+  id: string
+  username: string
+  text: string
+  createdAt: number
+}
+
+type LiveChatRoom = {
+  messages: LiveChatMessage[]
+  sockets: Set<string>
+}
+
+const MAX_MESSAGES_PER_ROOM = 100
+
+export class LiveChatStore {
+  private readonly rooms = new Map<string, LiveChatRoom>()
+
+  joinRoom (streamKey: string, socketId: string) {
+    const room = this.getOrCreateRoom(streamKey)
+
+    room.sockets.add(socketId)
+
+    return room
+  }
+
+  leaveRoom (streamKey: string, socketId: string) {
+    const room = this.rooms.get(streamKey)
+    if (!room) return
+
+    room.sockets.delete(socketId)
+
+    if (room.sockets.size === 0 && room.messages.length === 0) {
+      this.rooms.delete(streamKey)
+    }
+  }
+
+  addMessage (streamKey: string, username: string, text: string) {
+    const room = this.getOrCreateRoom(streamKey)
+    const message: LiveChatMessage = {
+      id: randomUUID(),
+      username,
+      text,
+      createdAt: Date.now()
+    }
+
+    room.messages.push(message)
+    if (room.messages.length > MAX_MESSAGES_PER_ROOM) {
+      room.messages.splice(0, room.messages.length - MAX_MESSAGES_PER_ROOM)
+    }
+
+    return message
+  }
+
+  getRecentMessages (streamKey: string) {
+    return [ ...(this.rooms.get(streamKey)?.messages || []) ]
+  }
+
+  getPresenceCount (streamKey: string) {
+    return this.rooms.get(streamKey)?.sockets.size || 0
+  }
+
+  deleteRoom (streamKey: string) {
+    return this.rooms.delete(streamKey)
+  }
+
+  private getOrCreateRoom (streamKey: string) {
+    let room = this.rooms.get(streamKey)
+
+    if (!room) {
+      room = {
+        messages: [],
+        sockets: new Set<string>()
+      }
+
+      this.rooms.set(streamKey, room)
+    }
+
+    return room
+  }
+}