Implement Firebase push notifications

backend/push_service.py

@@ -5,6 +5,11 @@ from typing import List, Optional
 from sqlalchemy.orm import Session
 from pywebpush import webpush, WebPushException
 from models import PushSubscription, User, Message, DMEnvelope
+from models import FcmToken
+import firebase_admin
+from firebase_admin import credentials as firebase_credentials
+from firebase_admin import messaging as firebase_messaging
+import base64
 
 logger = logging.getLogger("uvicorn.error")
 
@@ -12,6 +17,24 @@ class PushNotificationService:
     def __init__(self):
         self.vapid_private_key = os.getenv("VAPID_PRIVATE_KEY")
         self.vapid_public_key = os.getenv("VAPID_PUBLIC_KEY")
+        # Firebase Admin initialization (modern API). Only FIREBASE_CERT env is supported.
+        self.firebase_initialized = False
+        try:
+            firebase_cert = os.getenv("FIREBASE_CERT")
+            if not firebase_cert:
+                raise RuntimeError("FIREBASE_CERT env variable is required for Firebase Admin SDK initialization")
+
+            # Support raw JSON or base64-encoded JSON in FIREBASE_CERT
+            decoded = base64.b64decode(firebase_cert).decode("utf-8")
+            sa_dict = json.loads(decoded)
+
+            cred = firebase_credentials.Certificate(sa_dict)
+            firebase_admin.initialize_app(cred)
+            self.firebase_initialized = True
+            logger.info("Firebase Admin SDK initialized for push sending (FIREBASE_CERT)")
+        except Exception as e:
+            logger.error(f"Failed to initialize Firebase Admin SDK from FIREBASE_CERT: {e}")
+            raise
 
         if (not self.vapid_public_key) or (not self.vapid_private_key):
             raise ValueError("VAPID public or private key is None")
@@ -57,42 +80,61 @@ class PushNotificationService:
             users = db.query(User).filter(User.id != message.user_id)
             if exclude_user_id:
                 users = users.filter(User.id != exclude_user_id)
-            
+
             for user in users:
                 # Check if user has push subscription before trying to send
+                # Try all FCM tokens first (Android). If none or all fail, fall back to web push subscription.
+                fcm_rows = db.query(FcmToken).filter(FcmToken.user_id == user.id).all()
+                payload_data = {
+                    "type": "public_message",
+                    "message_id": message.id,
+                    "sender_id": message.user_id,
+                    "sender_username": message.author.username
+                }
+                title = f"{message.author.username}"
+                body = message.content[:100] + ("..." if len(message.content) > 100 else "")
+
+                if fcm_rows and self.firebase_initialized:
+                    for fcm in fcm_rows:
+                        try:
+                            self._send_fcm_to_token(fcm.token, title, body, payload_data)
+                        except Exception as e:
+                            logger.error(f"Failed to send FCM to user {user.id} token {fcm.token}: {e}")
+                            # Check if this is a permanent failure and clean up the token
+                            self._cleanup_failed_fcm_token(db, fcm, str(e))
+
                 subscription = db.query(PushSubscription).filter(PushSubscription.user_id == user.id).first()
-                if not subscription:
-                    continue
-                    
-                await self._send_notification_to_user(
-                    db, user.id, 
-                    f"New message from {message.author.username}",
-                    message.content[:100] + ("..." if len(message.content) > 100 else ""),
-                    message.author.profile_picture,
-                    {
-                        "type": "public_message",
-                        "message_id": message.id,
-                        "sender_id": message.user_id,
-                        "sender_username": message.author.username
-                    }
-                )
+                if subscription:
+                    await self._send_notification_to_user(
+                        db, user.id, title, body, message.author.profile_picture, payload_data
+                    )
         except Exception as e:
             logger.error(f"Failed to send public message notifications: {e}")
 
     async def send_dm_notification(self, db: Session, dm_envelope: DMEnvelope, sender: User):
         """Send push notification for a new DM"""
         try:
+            title = f"{sender.username}"
+            body = "New direct message"
+            payload_data = {
+                "type": "dm",
+                "dm_id": dm_envelope.id,
+                "sender_id": sender.id,
+                "sender_username": sender.username
+            }
+
+            fcm_rows = db.query(FcmToken).filter(FcmToken.user_id == dm_envelope.recipient_id).all()
+            if fcm_rows and self.firebase_initialized:
+                for fcm in fcm_rows:
+                    try:
+                        self._send_fcm_to_token(fcm.token, title, body, payload_data)
+                    except Exception as e:
+                        logger.error(f"Failed to send FCM to user {dm_envelope.recipient_id} token {fcm.token}: {e}")
+                        # Check if this is a permanent failure and clean up the token
+                        self._cleanup_failed_fcm_token(db, fcm, str(e))
+
             await self._send_notification_to_user(
-                db, dm_envelope.recipient_id,
-                f"New message from {sender.username}",
-                "You have a new direct message",
-                sender.profile_picture,
-                {
-                    "type": "dm",
-                    "dm_id": dm_envelope.id,
-                    "sender_id": sender.id,
-                    "sender_username": sender.username
-                }
+                db, dm_envelope.recipient_id, title, body, sender.profile_picture, payload_data
             )
         except Exception as e:
             logger.error(f"Failed to send DM notification: {e}")
@@ -136,6 +178,56 @@ class PushNotificationService:
         except Exception as e:
             logger.error(f"Failed to send push notification to user {user_id}: {e}")
 
+    def _send_fcm_to_token(self, token: str, title: str, body: str, data: dict):
+        """Send an FCM data-only push to a single device token using Firebase Admin SDK.
+        Notification display is handled by the app, not FCM."""
+        if not self.firebase_initialized:
+            raise RuntimeError("Firebase Admin SDK not initialized (FIREBASE_CERT required)")
+
+        try:
+            # Send only data payload - let the app handle notification display
+            # This prevents FCM from auto-showing notifications
+            msg = firebase_messaging.Message(
+                token=token,
+                data={
+                    "title": title,
+                    "body": body,
+                    **{k: str(v) for k, v in (data or {}).items()}
+                },
+                android=firebase_messaging.AndroidConfig(priority="high"),
+                apns=firebase_messaging.APNSConfig(headers={"apns-priority": "10"})
+            )
+            resp = firebase_messaging.send(msg)
+            return resp
+        except Exception as e:
+            logger.error(f"Firebase Admin send failed for token {token}: {e}")
+            raise
+
+    def _cleanup_failed_fcm_token(self, db: Session, fcm_token_entry, error_message: str):
+        """Clean up FCM tokens that have permanent failures"""
+        try:
+            # Check for permanent failure indicators in the error message
+            permanent_errors = [
+                "unregistered", "invalidregistration", "notregistered",
+                "sender_id_mismatch", "invalid_argument"
+            ]
+
+            error_lower = error_message.lower()
+            is_permanent = any(permanent_error in error_lower for permanent_error in permanent_errors)
+
+            if is_permanent:
+                logger.info(f"Removing permanently failed FCM token for user {fcm_token_entry.user_id}: {fcm_token_entry.token}")
+                db.query(FcmToken).filter(FcmToken.id == fcm_token_entry.id).delete()
+                db.commit()
+            else:
+                logger.debug(f"Temporary FCM failure for token {fcm_token_entry.token}, keeping token: {error_message}")
+        except Exception as e:
+            logger.error(f"Failed to cleanup FCM token {fcm_token_entry.token}: {e}")
+            try:
+                db.rollback()
+            except Exception:
+                pass
+
     async def unsubscribe_user(self, db: Session, user_id: int) -> bool:
         """Unsubscribe a user from push notifications"""
         try: