Create server_diff_graceful.py

Author: rogers-cyber

159-Real-time-collaboration-editor/server_diff_graceful.py

@@ -0,0 +1,83 @@
+# server_diff_graceful.py
+import asyncio
+import json
+import websockets
+from difflib import SequenceMatcher
+
+PORT = 8765
+
+# ---------------- GLOBAL STATE ---------------- #
+document_content = ""  # Shared document
+clients = {}  # websocket -> username
+lock = asyncio.Lock()  # Async lock for safe updates
+
+# ---------------- DIFF HELPERS ---------------- #
+def apply_diff(content, ops):
+    """Apply a list of diff operations to content"""
+    new_content = []
+    for op in ops:
+        tag = op["tag"]
+        i1, i2, text = op["i1"], op["i2"], op.get("text", "")
+        if tag == "equal":
+            new_content.append(content[i1:i2])
+        elif tag in ("replace", "insert"):
+            new_content.append(text)
+        elif tag == "delete":
+            pass  # skip deleted text
+    return "".join(new_content)
+
+# ---------------- BROADCAST ---------------- #
+async def broadcast(message, exclude=None):
+    """Send a message to all clients except the sender"""
+    if clients:
+        websockets_to_send = [ws for ws in clients if ws != exclude]
+        if websockets_to_send:
+            await asyncio.gather(*(ws.send(message) for ws in websockets_to_send))
+
+# ---------------- HANDLER ---------------- #
+async def handler(websocket):
+    global document_content
+    # Receive initial username
+    username = await websocket.recv()
+    clients[websocket] = username
+    print(f"[+] {username} connected")
+    
+    # Send full document to new client
+    await websocket.send(json.dumps({"type": "full_update", "content": document_content}))
+    
+    try:
+        async for message in websocket:
+            data = json.loads(message)
+            
+            async with lock:
+                if data["type"] == "diff":
+                    # Apply diff to server content
+                    document_content = apply_diff(document_content, data["ops"])
+                    # Broadcast diff to others
+                    await broadcast(json.dumps({"type": "diff", "ops": data["ops"], "user": username}), exclude=websocket)
+                
+                elif data["type"] == "cursor":
+                    # Broadcast cursor positions to other clients
+                    await broadcast(json.dumps({
+                        "type": "cursor",
+                        "position": data["position"],
+                        "user": username
+                    }), exclude=websocket)
+                    
+    except websockets.ConnectionClosed:
+        print(f"[-] {username} disconnected")
+    finally:
+        if websocket in clients:
+            del clients[websocket]
+
+# ---------------- START SERVER ---------------- #
+async def main():
+    async with websockets.serve(handler, "0.0.0.0", PORT):
+        print(f"Diff-Based Collaborative Server running on port {PORT}")
+        await asyncio.Future()  # run forever
+
+if __name__ == "__main__":
+    try:
+        asyncio.run(main())
+    except KeyboardInterrupt:
+        print("\nServer stopped gracefully.")