From 490fb769df1a85a9abc9c2a9ab3396c636c97606 Mon Sep 17 00:00:00 2001
From: Leopoldadmin <leopold.hammerschmidt@media-on.de>
Date: Mon, 22 Jun 2026 05:52:58 +0000
Subject: [PATCH] feat: Add Yjs WebSocket server implementation

---
 backend/src/websocket/yjsServer.ts | 107 +++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100644 backend/src/websocket/yjsServer.ts

diff --git a/backend/src/websocket/yjsServer.ts b/backend/src/websocket/yjsServer.ts
new file mode 100644
index 0000000..4f0f2d9
--- /dev/null
+++ b/backend/src/websocket/yjsServer.ts
@@ -0,0 +1,107 @@
+import { WebsocketProvider } from 'y-websocket'
+import * as Y from 'yjs'
+import { LeveldbPersistence } from 'y-leveldb'
+import * as fs from 'fs'
+import * as path from 'path'
+
+// Ensure the data directory exists
+const yjsDataDir = '/data/yjs'
+if (!fs.existsSync(yjsDataDir)) {
+  fs.mkdirSync(yjsDataDir, { recursive: true })
+}
+
+// Map to store documents and their persistence
+const documents = new Map<string, { doc: Y.Doc, persistence: LeveldbPersistence }>()
+
+// Function to get or create a document for a project
+async function getDocument(projectId: string): Promise<Y.Doc> {
+  const roomName = `project:${projectId}`
+  
+  if (documents.has(roomName)) {
+    return documents.get(roomName)!.doc
+  }
+  
+  // Create a new document
+  const doc = new Y.Doc()
+  
+  // Set up persistence
+  const dbPath = path.join(yjsDataDir, `${projectId}.ldb`)
+  const persistence = new LeveldbPersistence(dbPath, doc)
+  
+  // Store the document and its persistence
+  documents.set(roomName, { doc, persistence })
+  
+  return doc
+}
+
+// Function to handle WebSocket connections
+async function handleWebSocketConnection(socket: any, request: any) {
+  try {
+    // Extract JWT token from query param or header
+    const token = request.query.token || request.headers.authorization?.replace('Bearer ', '')
+    
+    // Verify JWT token (implementation depends on your auth system)
+    // const user = verifyJWT(token)
+    
+    // For now, we'll use a mock user object
+    const user = {
+      id: 'user123',
+      role: 'editor' // or 'viewer' for read-only users
+    }
+    
+    // Extract project ID from the room name
+    const url = new URL(socket.url, 'ws://localhost')
+    const roomName = url.searchParams.get('room')
+    
+    if (!roomName || !roomName.startsWith('project:')) {
+      socket.close(4000, 'Invalid room name')
+      return
+    }
+    
+    const projectId = roomName.replace('project:', '')
+    
+    // Get or create the document for this project
+    const doc = await getDocument(projectId)
+    
+    // Set up the WebSocket provider
+    const provider = new WebsocketProvider('ws://localhost:3001', roomName, doc, {
+      WebSocket: socket.constructor,
+      resyncInterval: false,
+      maxBackoffTime: 2500,
+      disableBc: true // Disable broadcast channel to ensure all messages go through the server
+    })
+    
+    // Handle read-only users
+    if (user.role === 'viewer') {
+      // Override the send method to prevent updates from read-only users
+      const originalSend = provider.send
+      provider.send = function (message: any) {
+        // Allow sync-step1, sync-step2, and awareness messages
+        // Block update messages
+        if (message[0] === 1) { // Update message type
+          console.log(`Blocking update from read-only user: ${user.id}`)
+          return
+        }
+        originalSend.call(this, message)
+      }
+    }
+    
+    // Handle awareness updates
+    provider.awareness.on('update', (changes: any) => {
+      // Broadcast awareness changes to all clients in the room
+      provider.broadcastAwareness()
+    })
+    
+    // Clean up when the connection closes
+    socket.on('close', () => {
+      provider.destroy()
+    })
+    
+  } catch (error) {
+    console.error('WebSocket connection error:', error)
+    socket.close(1011, 'Internal server error')
+  }
+}
+
+// Export functions for use in the Fastify server
+export { handleWebSocketConnection, getDocument }