const express = require('express');
const { Client, LocalAuth } = require('whatsapp-web.js');
const qrcode = require('qrcode-terminal');

const app = express();
const PORT = process.env.PORT || 5001;

app.use(express.json());

// Initialize WhatsApp Web Client with LocalAuth to persist session
const client = new Client({
    authStrategy: new LocalAuth({
        dataPath: './.wwebjs_auth'
    }),
    puppeteer: {
        headless: true,
        executablePath: process.env.PUPPETEER_EXECUTABLE_PATH || '/usr/bin/chromium-browser',
        args: [
            '--no-sandbox',
            '--disable-setuid-sandbox',
            '--disable-dev-shm-usage',
            '--disable-accelerated-2d-canvas',
            '--disable-gpu',
            '--no-first-run',
            '--disable-extensions',
            '--disable-background-networking',
            '--disable-default-apps',
            '--disable-background-timer-throttling',
            '--disable-renderer-backgrounding',
            '--disable-backgrounding-occluded-windows'
        ]
    }
});

let isReady = false;

// Event: QR Code generation
client.on('qr', (qr) => {
    console.log('\n==================================================================');
    console.log('SCAN THIS QR CODE WITH YOUR WHATSAPP APP TO LOG IN:');
    console.log('==================================================================\n');
    qrcode.generate(qr, { small: true });
    console.log('\n==================================================================');
    console.log('[WhatsApp Bot] QR code generated. Waiting for scan...');
});

// Log loading progress
client.on('loading_screen', (percent, message) => {
    console.log(`[WhatsApp Bot] Loading: ${percent}% - ${message}`);
});

client.on('authenticated', () => {
    console.log('[WhatsApp Bot] Authenticated successfully!');
});

// Event: Successfully logged in & authenticated
client.on('ready', () => {
    console.log('\n[WhatsApp Bot] Client is ready and authenticated!');
    isReady = true;
});

client.on('auth_failure', (msg) => {
    console.error('[WhatsApp Bot] Authentication failure:', msg);
});

client.on('disconnected', (reason) => {
    console.log('[WhatsApp Bot] Client was logged out:', reason);
    isReady = false;
});

// HTTP REST Endpoint to send messages
app.post('/send-message', async (req, res) => {
    if (!isReady) {
        return res.status(503).json({ success: false, error: 'WhatsApp Web client is not ready. Please scan the QR code in the server terminal.' });
    }

    const { to, message } = req.body;
    if (!to || !message) {
        return res.status(400).json({ success: false, error: "Missing 'to' or 'message' fields in JSON payload." });
    }

    try {
        let targetJid = to;

        // 1. Check if 'to' is a WhatsApp group invite link or invite code
        if (to.includes('chat.whatsapp.com') || /^[A-Za-z0-9]{20,24}$/.test(to)) {
            let inviteCode = to;
            if (to.includes('chat.whatsapp.com/')) {
                inviteCode = to.split('chat.whatsapp.com/')[1].split('?')[0].trim();
            }
            console.log(`[WhatsApp Bot] Attempting to join group via invite code: ${inviteCode}`);
            try {
                const groupChatId = await client.acceptInvite(inviteCode);
                targetJid = groupChatId;
                console.log(`[WhatsApp Bot] Successfully joined/resolved group. JID: ${targetJid}`);
            } catch (err) {
                console.warn(`[WhatsApp Bot] Accept invite failed (bot might already be in the group):`, err.message);
                // Fallback: If joining failed, attempt to find by code if we can't join
                return res.status(400).json({ success: false, error: `Failed to join group via invite code: ${err.message}` });
            }
        }

        // 2. Format phone number to standard JID format if it is a plain phone number
        if (!targetJid.includes('@')) {
            // Strip any prefix, plus, space, parentheses, or dashes
            let cleanPhone = targetJid.replace('whatsapp:', '').replace(/[+\s()-]/g, '').trim();
            targetJid = `${cleanPhone}@c.us`;
        }

        console.log(`[WhatsApp Bot] Sending message to target JID: ${targetJid}`);
        const response = await client.sendMessage(targetJid, message);
        
        res.json({ 
            success: true, 
            messageId: response.id._serialized,
            recipient: targetJid 
        });

    } catch (error) {
        console.error(`[WhatsApp Bot] Failed to send message:`, error);
        res.status(500).json({ success: false, error: error.message || error });
    }
});

// Health check endpoint
app.get('/status', (req, res) => {
    res.json({
        service: 'whatsapp-gateway',
        ready: isReady,
        authenticated: client.info ? true : false
    });
});

app.listen(PORT, () => {
    console.log(`[WhatsApp Bot Gateway] REST API running at http://localhost:${PORT}`);
});

console.log('[WhatsApp Bot] Initializing client...');
client.initialize();