bun add @capacitor/push-notifications
bunx cap sync

import { PushNotifications } from '@capacitor/push-notifications';

async function initPushNotifications() {
  // Request permission
  const permission = await PushNotifications.requestPermissions();

  if (permission.receive === 'granted') {
    // Register for push
    await PushNotifications.register();
  }

  // Get FCM token
  PushNotifications.addListener('registration', (token) => {
    console.log('Push token:', token.value);
    // Send token to your server
    sendTokenToServer(token.value);
  });

  // Handle registration error
  PushNotifications.addListener('registrationError', (error) => {
    console.error('Registration error:', error);
  });

  // Handle incoming notification (foreground)
  PushNotifications.addListener('pushNotificationReceived', (notification) => {
    console.log('Notification received:', notification);
    // Show in-app notification
    showInAppNotification(notification);
  });

  // Handle notification tap
  PushNotifications.addListener('pushNotificationActionPerformed', (action) => {
    console.log('Notification action:', action);
    // Navigate based on notification data
    handleNotificationTap(action.notification);
  });
}

// android/build.gradle
buildscript {
    dependencies {
        classpath 'com.google.gms:google-services:4.4.0'
    }
}

// android/app/build.gradle
apply plugin: 'com.google.gms.google-services'

dependencies {
    implementation platform('com.google.firebase:firebase-bom:32.7.0')
    implementation 'com.google.firebase:firebase-messaging'
}

# ios/App/Podfile
pod 'Firebase/Messaging'

// ios/App/App/AppDelegate.swift
import Firebase
import FirebaseMessaging

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    func application(
        _ application: UIApplication,
        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
    ) -> Bool {
        FirebaseApp.configure()
        return true
    }

    func application(
        _ application: UIApplication,
        didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data
    ) {
        Messaging.messaging().apnsToken = deviceToken
    }
}

import admin from 'firebase-admin';

// Initialize
admin.initializeApp({
  credential: admin.credential.cert(serviceAccount),
});

// Send to single device
async function sendToDevice(token: string) {
  await admin.messaging().send({
    token,
    notification: {
      title: 'Hello!',
      body: 'You have a new message',
    },
    data: {
      type: 'message',
      messageId: '123',
    },
    android: {
      priority: 'high',
      notification: {
        channelId: 'messages',
        icon: 'ic_notification',
        color: '#4285f4',
      },
    },
    apns: {
      payload: {
        aps: {
          badge: 1,
          sound: 'default',
        },
      },
    },
  });
}

// Send to topic
async function sendToTopic(topic: string) {
  await admin.messaging().send({
    topic,
    notification: {
      title: 'Breaking News',
      body: 'Something important happened',
    },
  });
}

// Send to multiple devices
async function sendToMultiple(tokens: string[]) {
  await admin.messaging().sendEachForMulticast({
    tokens,
    notification: {
      title: 'Update',
      body: 'New features available',
    },
  });
}

curl -X POST \
  'https://fcm.googleapis.com/v1/projects/YOUR_PROJECT/messages:send' \
  -H 'Authorization: Bearer ACCESS_TOKEN' \
  -H 'Content-Type: application/json' \
  -d '{
    "message": {
      "token": "DEVICE_TOKEN",
      "notification": {
        "title": "Hello",
        "body": "World"
      }
    }
  }'

import { PushNotifications } from '@capacitor/push-notifications';

// Create channel
await PushNotifications.createChannel({
  id: 'messages',
  name: 'Messages',
  description: 'Message notifications',
  importance: 5, // Max importance
  visibility: 1, // Public
  sound: 'notification.wav',
  vibration: true,
  lights: true,
  lightColor: '#FF0000',
});

// Delete channel
await PushNotifications.deleteChannel({ id: 'old-channel' });

// List channels
const channels = await PushNotifications.listChannels();

// Subscribe to topic
await PushNotifications.addListener('registration', async () => {
  // Subscribe to topics based on user preferences
  const messaging = getMessaging();
  await subscribeToTopic(messaging, 'news');
  await subscribeToTopic(messaging, 'promotions');
});

// ios/App/NotificationService/NotificationService.swift
import UserNotifications

class NotificationService: UNNotificationServiceExtension {
    override func didReceive(
        _ request: UNNotificationRequest,
        withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void
    ) {
        guard let mutableContent = request.content.mutableCopy() as? UNMutableNotificationContent else {
            contentHandler(request.content)
            return
        }

        // Add image
        if let imageUrl = request.content.userInfo["image"] as? String,
           let url = URL(string: imageUrl) {
            downloadImage(url: url) { attachment in
                if let attachment = attachment {
                    mutableContent.attachments = [attachment]
                }
                contentHandler(mutableContent)
            }
        } else {
            contentHandler(mutableContent)
        }
    }
}

// Handle action buttons
PushNotifications.addListener('pushNotificationActionPerformed', (action) => {
  switch (action.actionId) {
    case 'reply':
      // Handle reply action
      const input = action.inputValue;
      sendReply(input);
      break;
    case 'dismiss':
      // Handle dismiss
      break;
    default:
      // Handle tap
      navigateToContent(action.notification.data);
  }
});

// Server-side: Send data-only message
{
  "to": "DEVICE_TOKEN",
  "data": {
    "type": "sync",
    "action": "refresh"
  }
  // No "notification" key = data-only
}

// android/app/src/main/java/.../FirebaseService.kt
class FirebaseService : FirebaseMessagingService() {
    override fun onMessageReceived(message: RemoteMessage) {
        // Handle data message in background
        message.data["type"]?.let { type ->
            when (type) {
                "sync" -> performBackgroundSync()
                "update" -> checkForUpdates()
            }
        }
    }
}

import { LocalNotifications } from '@capacitor/local-notifications';

// Show local notification when in foreground
PushNotifications.addListener('pushNotificationReceived', async (notification) => {
  await LocalNotifications.schedule({
    notifications: [
      {
        id: Date.now(),
        title: notification.title || '',
        body: notification.body || '',
        extra: notification.data,
      },
    ],
  });
});

async function requestNotificationPermission() {
  const { receive } = await PushNotifications.checkPermissions();

  if (receive === 'prompt') {
    // Show explanation first
    const shouldRequest = await showPermissionExplanation();

    if (shouldRequest) {
      const result = await PushNotifications.requestPermissions();
      return result.receive === 'granted';
    }
    return false;
  }

  if (receive === 'denied') {
    // Guide user to settings
    showSettingsPrompt();
    return false;
  }

  return receive === 'granted';
}

// Handle token refresh
PushNotifications.addListener('registration', async (token) => {
  const oldToken = await getStoredToken();

  if (oldToken !== token.value) {
    // Token changed, update server
    await updateServerToken(oldToken, token.value);
    await storeToken(token.value);
  }
});

PushNotifications.addListener('registrationError', (error) => {
  console.error('Push registration failed:', error);

  // Log to analytics
  analytics.logEvent('push_registration_failed', {
    error: error.error,
  });

  // Retry with backoff
  scheduleRetry();
});