AUTOMATIC_NOTIFICATIONS_GUIDE.md

Automatic Notifications Setup Guide

Current Status

✅ Fixed: Code now separates FCM tokens from Expo tokens ⚠️ Issue: FCM tokens need proper backend to send notifications

Why FCM Tokens Don't Work from Client

Security: FCM requires a Server Key which should NEVER be exposed in client code.

Current Flow:

Admin updates price → sendPushNotifications() called
├── ✅ Expo tokens: Sent via Expo service (works)
└── ❌ FCM tokens: Logged but not sent (needs backend)

---

Solution Options

Option 1: Manual (Temporary - Works Now!)

When admin updates prices, manually send from Firebase Console:

1. Admin updates price in app
2. Check console logs for FCM tokens
3. Open Firebase Console → Cloud Messaging
4. Click "Send test message"
5. Paste FCM token
6. Enter notification details
7. Send

Pros: Works immediately, no code changes Cons: Manual process each time

---

Option 2: Client-Side FCM (Quick but NOT Recommended)

Add FCM Server Key to client code for testing.

⚠️ WARNING: This exposes your server key - only for testing!

Steps:

1. Get FCM Server Key:

• Firebase Console → Project Settings → Cloud Messaging
• Copy Server Key (starts with "AAAA...")

2. Add to .env:

EXPO_PUBLIC_FCM_SERVER_KEY="AAAA..." # Your server key

3. Update AdminPriceFormScreen.tsx:

Replace the FCM section (lines 171-180) with:

// Send to FCM tokens (production users)
if (fcmTokens.length > 0) {
  console.log(`Sending to ${fcmTokens.length} FCM tokens`);

  const FCM_SERVER_KEY = process.env.EXPO_PUBLIC_FCM_SERVER_KEY;

  if (!FCM_SERVER_KEY) {
    console.error('FCM_SERVER_KEY not found in .env');
  } else {
    for (const token of fcmTokens) {
      try {
        await fetch('https://fcm.googleapis.com/fcm/send', {
          method: 'POST',
          headers: {
            'Authorization': `key=${FCM_SERVER_KEY}`,
            'Content-Type': 'application/json',
          },
          body: JSON.stringify({
            to: token,
            notification: {
              title: notificationTitle,
              body: notificationBody,
              icon: 'notification_icon',
              color: '#3B82F6',
            },
            data: {
              screen: 'Market',
              market: priceData.market,
              breed: priceData.breed,
            },
          }),
        });
        console.log(`FCM notification sent to: ${token.substring(0, 20)}...`);
      } catch (error) {
        console.error('FCM send error:', error);
      }
    }
  }
}

Pros: Works automatically, immediate solution Cons:

• ⚠️ Security risk (server key in client)
• ⚠️ Not recommended for production
• ⚠️ Anyone can decompile APK and steal key

---

Option 3: Firebase Cloud Functions (RECOMMENDED - Production Ready)

Proper backend solution - notifications sent from secure server.

Architecture:

Admin updates price → Firestore updated → Cloud Function triggered → Send FCM notifications

Setup Steps:

1. Install Firebase CLI:

npm install -g firebase-tools
firebase login

2. Initialize Cloud Functions:

firebase init functions
# Select: JavaScript or TypeScript
# Install dependencies: Yes

3. Create Function (functions/index.js):

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();

exports.sendPriceUpdateNotification = functions.firestore
  .document('cocoonPrices/{priceId}')
  .onWrite(async (change, context) => {
    // Triggered when price is added or updated
    const priceData = change.after.data();

    if (!priceData) return; // Document was deleted

    try {
      // Get all FCM tokens
      const tokensSnapshot = await admin.firestore()
        .collection('pushTokens')
        .where('tokenType', '==', 'fcm')
        .get();

      const tokens = tokensSnapshot.docs.map(doc => doc.data().token);

      if (tokens.length === 0) {
        console.log('No FCM tokens found');
        return;
      }

      // Create notification message
      const message = {
        notification: {
          title: `${priceData.market} - ${priceData.breed} Price Update`,
          body: `Min: ₹${priceData.minPrice} | Max: ₹${priceData.maxPrice} | Avg: ₹${priceData.avgPrice}/kg`,
        },
        data: {
          screen: 'Market',
          market: priceData.market,
          breed: priceData.breed,
        },
        tokens: tokens,
      };

      // Send to all FCM tokens
      const response = await admin.messaging().sendEachForMulticast(message);

      console.log(`✅ Successfully sent: ${response.successCount}`);
      console.log(`❌ Failed: ${response.failureCount}`);

      // Clean up invalid tokens
      if (response.failureCount > 0) {
        const failedTokens = [];
        response.responses.forEach((resp, idx) => {
          if (!resp.success) {
            failedTokens.push(tokens[idx]);
          }
        });

        // Delete invalid tokens
        for (const token of failedTokens) {
          await admin.firestore().collection('pushTokens').doc(token).delete();
        }
        console.log(`🗑️ Cleaned up ${failedTokens.length} invalid tokens`);
      }

    } catch (error) {
      console.error('Error sending notification:', error);
    }
  });

4. Deploy:

firebase deploy --only functions

5. Remove client-side notification code:

Update AdminPriceFormScreen.tsx - remove the await sendPushNotifications(priceData); call on line 148 since Cloud Function handles it automatically.

Pros:

• ✅ Secure (server key never exposed)
• ✅ Automatic (triggers on Firestore changes)
• ✅ Production-ready
• ✅ Reliable (runs on Google servers)

Cons:

• Requires Firebase billing (free tier available)
• Initial setup time

---

Recommended Path

For Immediate Testing (Today): → Use Option 1 (Manual Firebase Console)

For Production (This Week): → Implement Option 3 (Cloud Functions)

Avoid: → Option 2 (Client-side FCM) - Security risk

---

Testing Checklist

After implementing your chosen option:

• Admin updates price in app
• Check Firestore - price updated
• Check console logs - FCM tokens identified
• Notification sent automatically (Option 2/3) or manually (Option 1)
• Production APK users receive notification
• Notification shows app icon
• Tapping notification opens app to Market screen

---

Current Code Status

✅ What's Working:

• Token type detection (FCM vs Expo)
• Expo token notifications (Expo Go users)
• Logging of FCM tokens

⚠️ What Needs Implementation:

• FCM notification sending (choose Option 1, 2, or 3)

---

Need Help?

Option 1 (Manual): Already working - just use Firebase Console Option 2 (Client-side): I can add the code if you provide FCM Server Key Option 3 (Cloud Functions): I can set up the complete Cloud Functions project

Which option would you like to implement?