feat: implement MatchingService with Redis queue, peer matching and timeout handling

Author: SherwynNg

services/matching-service/app/services/matching.py

@@ -0,0 +1,62 @@
+from app.models.match import MatchRequest, MatchResponse
+import uuid
+from app.services import queue
+import time
+import asyncio
+from app.services.websocket_manager import manager
+
+TIMEOUT_SECONDS = 60
+
+class MatchingService:
+
+    @staticmethod
+    async def join_queue(request: MatchRequest) -> MatchResponse:
+        difficulty = request.difficulty
+        topic = request.topic
+        language = request.language
+        user_id = request.user_id
+
+        peer_id = queue.dequeue_user(difficulty, topic, language)
+
+        # suitable match
+        if peer_id:
+            await manager.send_event(user_id, "match.found", {"peer_id": peer_id})
+            await manager.send_event(peer_id, "match.found", {"peer_id": user_id})
+
+            # TODO: Initialise collaboration session and assign question
+
+            return MatchResponse(success=True, peer_id=peer_id, message="Peer found")
+        else:
+            # no suitable match
+            queue.enqueue_user(difficulty, topic, language, user_id)
+            position = queue.get_queue_position(difficulty, topic, language, user_id)
+
+            return MatchResponse(
+                success=True,
+                message="Added to queue",
+                # queue_position=position
+            )
+        
+    @staticmethod
+    def cancel_queue(request: MatchRequest) -> MatchResponse:
+        removed = queue.remove_user(request.difficulty, request.topic, request.language, request.user_id)
+        if removed:
+            return MatchResponse(success=True, message="Removed from queue")
+        else:
+            return MatchResponse(success=False, message="User not in queue")
+
+    @staticmethod
+    async def check_timeouts(request: MatchRequest):
+        await asyncio.sleep(TIMEOUT_SECONDS)
+        position = queue.get_queue_position(request.difficulty, request.topic, request.language, request.user_id)
+
+        if position is not None:
+            queue.remove_user(request.difficulty, request.topic, request.language, request.user_id)
+            print(f"Timeout: Removed user {request.user_id} from queue after {TIMEOUT_SECONDS}")
+            
+            # send WebSocket event timeout
+            await manager.send_event(
+                request.user_id,
+                "match.timeout",
+                {"message": f"Timeout after {TIMEOUT_SECONDS} seconds, removed from queue"}
+            )