feat: sending notifications on invites creation

backend/src/main/java/online/wesal/wesal/repository/UserRepository.java

@@ -2,8 +2,11 @@ package online.wesal.wesal.repository;
 
 import online.wesal.wesal.entity.User;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 import org.springframework.stereotype.Repository;
 
+import java.util.List;
 import java.util.Optional;
 
 @Repository
@@ -12,4 +15,7 @@ public interface UserRepository extends JpaRepository<User, Long> {
     Optional<User> findByUsername(String username);
     boolean existsByEmail(String email);
     boolean existsByUsername(String username);
+    
+    @Query("SELECT u FROM User u WHERE u.subscriptions LIKE %:subscription% AND u.fcmToken IS NOT NULL AND u.fcmToken != ''")
+    List<User> findUsersSubscribedTo(@Param("subscription") String subscription);
 }

backend/src/main/java/online/wesal/wesal/service/InvitationService.java

@@ -38,6 +38,9 @@ public class InvitationService {
     @Autowired
     private FCMNotificationService fcmNotificationService;
     
+    @Autowired
+    private SubscriptionNotificationService subscriptionNotificationService;
+    
     @Transactional
     public InvitationResponse createInvitation(CreateInvitationRequest request, String userEmail) {
         User creator = userRepository.findByEmail(userEmail)
@@ -58,6 +61,15 @@ public class InvitationService {
         invitation.setLocation(request.getLocation());
         
         Invitation saved = invitationRepository.save(invitation);
+        
+        // Send notification to users subscribed to "newinvites"
+        String title = "New Invitation! \uD83C\uDF89";
+        String body = String.format("%s is looking for people to join them for %s: %s", 
+                                   creator.getDisplayName(), 
+                                   tag.getName(), 
+                                   saved.getTitle());
+        subscriptionNotificationService.sendNotificationToSubscription("newinvites", title, body);
+        
         return mapToResponse(saved);
     }
     

backend/src/main/java/online/wesal/wesal/service/SubscriptionNotificationService.java

@@ -0,0 +1,77 @@
+package online.wesal.wesal.service;
+
+import com.google.firebase.messaging.FirebaseMessaging;
+import com.google.firebase.messaging.MulticastMessage;
+import com.google.firebase.messaging.Notification;
+import com.google.firebase.messaging.BatchResponse;
+import online.wesal.wesal.entity.User;
+import online.wesal.wesal.repository.UserRepository;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.scheduling.annotation.Async;
+import org.springframework.stereotype.Service;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+@Service
+public class SubscriptionNotificationService {
+
+    private static final Logger logger = LoggerFactory.getLogger(SubscriptionNotificationService.class);
+
+    @Autowired
+    private UserRepository userRepository;
+
+    @Async
+    public void sendNotificationToSubscription(String subscriptionName, String title, String body) {
+        try {
+            // Get all users subscribed to the given subscription
+            List<User> subscribedUsers = userRepository.findUsersSubscribedTo(subscriptionName);
+            
+            if (subscribedUsers.isEmpty()) {
+                logger.info("No users found subscribed to '{}'", subscriptionName);
+                return;
+            }
+
+            // Extract FCM tokens from subscribed users
+            List<String> tokens = subscribedUsers.stream()
+                    .map(User::getFcmToken)
+                    .filter(token -> token != null && !token.trim().isEmpty())
+                    .collect(Collectors.toList());
+
+            if (tokens.isEmpty()) {
+                logger.warn("No valid FCM tokens found for subscription '{}'", subscriptionName);
+                return;
+            }
+
+            // Create multicast message
+            MulticastMessage message = MulticastMessage.builder()
+                    .setNotification(Notification.builder()
+                            .setTitle(title)
+                            .setBody(body)
+                            .build())
+                    .addAllTokens(tokens)
+                    .build();
+
+            // Send the multicast message
+            BatchResponse response = FirebaseMessaging.getInstance().sendEachForMulticast(message);
+            
+            logger.info("Successfully sent notifications for subscription '{}': {} successful, {} failed", 
+                       subscriptionName, response.getSuccessCount(), response.getFailureCount());
+            
+            // Log any failures for debugging
+            if (response.getFailureCount() > 0) {
+                for (int i = 0; i < response.getResponses().size(); i++) {
+                    if (!response.getResponses().get(i).isSuccessful()) {
+                        logger.error("Failed to send notification to token {}: {}", 
+                                   tokens.get(i), response.getResponses().get(i).getException().getMessage());
+                    }
+                }
+            }
+
+        } catch (Exception e) {
+            logger.error("Failed to send notifications for subscription '{}': {}", subscriptionName, e.getMessage(), e);
+        }
+    }
+}