FCM Push Notifications with API only

fcm_push_notification.js

const jwt = require('jsonwebtoken');
const axios = require('axios');
const fs = require('fs');

function getFCMAccessToken() {
    const creds = JSON.parse(process.env.SERVICE_ACCOUNT_JSON || '{}');
    const privateKey = creds.private_key.replace(/\\n/g, '\n');
    const clientEmail = creds.client_email;
    const scopes = ['https://www.googleapis.com/auth/firebase.messaging'];
    const url = 'https://oauth2.googleapis.com/token';
    
    const now = Math.floor(Date.now() / 1000);
    const payload = {
        iss: clientEmail,
        sub: clientEmail,
        scope: scopes.join(' '),
        aud: url,
        exp: now + 10,
        iat: now,
    };
    
    const token = jwt.sign(payload, privateKey, { algorithm: 'RS256' });
    
    return axios.post(url, {
        assertion: token,
        grant_type: 'urn:ietf:params:oauth:grant-type:jwt-bearer'
    }).then(response => response.data.access_token)
    .catch(error => {
        console.error('Error fetching access token:', error.response?.data || error.message);
        return null;
    });
}

async function pushFCMByToken(token, title, content, extraData = null, picture = null) {
    const apiKey = await getFCMAccessToken();
    if (!apiKey) return { code: 'error', message: 'Failed to get access token', data: null };
    
    const projectId = process.env.FIREBASE_PROJECT_ID;
    const url = `https://fcm.googleapis.com/v1/projects/${projectId}/messages:send`;
    
    const message = {
        message: {
            token,
            notification: { title, body: content },
            data: extraData,
        }
    };
    
    if (picture) {
        message.message.android = { notification: { image: picture } };
        message.message.apns = { payload: { aps: { 'mutable-content': 1 } }, fcm_options: { image: picture } };
        message.message.webpush = { headers: { image: picture } };
    }
    
    try {
        const response = await axios.post(url, message, {
            headers: { Authorization: `Bearer ${apiKey}`, 'Content-Type': 'application/json' }
        });
        return { code: 'success', message: 'Notification sent successfully.', data: response.data };
    } catch (error) {
        return { code: 'error', message: error.response?.data?.message || 'Unable to deliver notification!', data: null };
    }
}

async function pushFCMByTopic(topic, title, content, extraData = null, picture = null) {
    const apiKey = await getFCMAccessToken();
    if (!apiKey) return { code: 'error', message: 'Failed to get access token', data: null };
    
    const projectId = process.env.FIREBASE_PROJECT_ID;
    const url = `https://fcm.googleapis.com/v1/projects/${projectId}/messages:send`;
    
    const message = {
        message: {
            topic,
            notification: { title, body: content },
            data: extraData,
        }
    };
    
    if (picture) {
        message.message.android = { notification: { image: picture } };
        message.message.apns = { payload: { aps: { 'mutable-content': 1 } }, fcm_options: { image: picture } };
        message.message.webpush = { headers: { image: picture } };
    }
    
    try {
        const response = await axios.post(url, message, {
            headers: { Authorization: `Bearer ${apiKey}`, 'Content-Type': 'application/json' }
        });
        return { code: 'success', message: 'Notification sent successfully.', data: response.data };
    } catch (error) {
        return { code: 'error', message: error.response?.data?.message || 'Unable to deliver notification!', data: null };
    }
}

module.exports = { getFCMAccessToken, pushFCMByToken, pushFCMByTopic };