const fs = require('fs');
const path = require('path');
const dotenv = require('dotenv');

// Find .env file identically to how PHP bootstrap does it
const envPaths = [
    path.join(__dirname, '.env'),
    path.join(__dirname, '../.env'),
    path.join(__dirname, '../backend/.env'),
    path.join(__dirname, '../../../.env')
];

for (const p of envPaths) {
    if (fs.existsSync(p)) {
        dotenv.config({ path: p });
        console.log(`Loaded environment from ${p}`);
        break;
    }
}

const express = require('express');
const cors = require('cors');
const { startSession, disconnectSession, sendMessage, getActiveSessions, checkContact, isSessionReady } = require('./baileys-client');

const app = express();
app.use(cors());
app.use(express.json({ limit: '50mb' }));
app.use(express.urlencoded({ limit: '50mb', extended: true }));

const PORT = process.env.PORT || 3722;

// Health check endpoint (Public)
app.get('/health', (req, res) => {
    res.json({ status: 'healthy', service: 'Flash Call OTP WhatsApp Gateway' });
});

// Security Middleware: Protect all /api/ routes
app.use('/api', (req, res, next) => {
    const secret = req.header('X-Webhook-Secret');
    if (!process.env.WEBHOOK_SECRET || secret !== process.env.WEBHOOK_SECRET) {
        return res.status(403).json({ error: 'Unauthorized gateway access' });
    }
    next();
});

// Start or retrieve a session
app.post('/api/sessions/start', async (req, res) => {
    const { session_key, webhook_url } = req.body;

    if (!session_key || !webhook_url) {
        return res.status(400).json({ error: 'Missing session_key or webhook_url' });
    }

    try {
        await startSession(session_key, webhook_url);
        res.json({ status: 'success', message: 'Session started or retrieved' });
    } catch (err) {
        console.error(`Error starting session ${session_key}:`, err);
        res.status(500).json({ error: 'Failed to start session' });
    }
});

// Disconnect and remove a session (e.g., when banned or logged out)
app.post('/api/sessions/disconnect', async (req, res) => {
    const { session_key } = req.body;

    if (!session_key) {
        return res.status(400).json({ error: 'Missing session_key' });
    }

    try {
        await disconnectSession(session_key);
        res.json({ status: 'success', message: 'Session disconnected and cleaned up' });
    } catch (err) {
        console.error(`Error disconnecting session ${session_key}:`, err);
        res.status(500).json({ error: 'Failed to disconnect session' });
    }
});

// Get list of active session keys in memory
app.get('/api/sessions/active', (req, res) => {
    res.json({ status: 'success', active_sessions: getActiveSessions() });
});

// Check if contact is on WhatsApp
app.post('/api/contacts/check', async (req, res) => {
    let { session_key, phone } = req.body;

    if (!session_key || !phone) {
        return res.status(400).json({ error: 'Missing session_key or phone' });
    }

    if (session_key === 'auto') {
        const activeSlots = [];
        for (let i = 1; i <= 3; i++) {
            if (isSessionReady(`slot-${i}`)) {
                activeSlots.push(`slot-${i}`);
            }
        }
        if (activeSlots.length === 0) {
            return res.status(503).json({ error: 'No WhatsApp slots are ready to check contacts' });
        }

        let checkError = null;
        for (const slotKey of activeSlots) {
            try {
                const result = await checkContact(slotKey, phone);
                return res.json({ status: 'success', session_key: slotKey, data: result });
            } catch (err) {
                console.error(`[ContactCheck] Failed check via ${slotKey}:`, err.message);
                checkError = err;
            }
        }
        return res.status(500).json({ error: `Failed to check contact via any active slot. Last error: ${checkError.message}` });
    }

    try {
        const result = await checkContact(session_key, phone);
        res.json({ status: 'success', data: result });
    } catch (err) {
        console.error(`Error checking contact ${phone} via ${session_key}:`, err);
        res.status(500).json({ error: err.message || 'Failed to check contact' });
    }
});

// Send outbound message
let currentSlotIndex = 1;

app.post('/api/messages/send', async (req, res) => {
    let { session_key, phone, message, media_url, audio, mimetype, image } = req.body;

    if (!session_key || !phone) {
        return res.status(400).json({ error: 'Missing session_key or phone' });
    }

    if (!message && !audio && !media_url && !image) {
        return res.status(400).json({ error: 'Missing message, audio, media_url, or image' });
    }

    try {
        if (session_key === 'auto') {
            let activeSlots = [];
            for (let i = 1; i <= 3; i++) {
                if (isSessionReady(`slot-${i}`)) {
                    activeSlots.push(`slot-${i}`);
                }
            }

            if (activeSlots.length === 0) {
                return res.status(503).json({ error: 'No WhatsApp slots are currently ready to send messages' });
            }

            let lastError = null;
            let attempts = 0;
            const maxAttempts = activeSlots.length;

            while (attempts < maxAttempts) {
                const selectedKey = activeSlots[currentSlotIndex % activeSlots.length];
                currentSlotIndex++;
                attempts++;

                try {
                    console.log(`[RoundRobin] Attempt ${attempts}/${maxAttempts}: Trying to send via ${selectedKey}`);
                    const result = await sendMessage(selectedKey, phone, message, media_url, audio, mimetype, image);
                    return res.json({ status: 'success', session_key: selectedKey, data: result });
                } catch (err) {
                    console.error(`[RoundRobin] Attempt ${attempts} failed via ${selectedKey}:`, err.message);
                    lastError = err;
                    
                    activeSlots = activeSlots.filter(s => s !== selectedKey);
                    if (activeSlots.length === 0) break;
                }
            }

            return res.status(500).json({ 
                error: `Failed to send message after trying all active slots. Last error: ${lastError ? lastError.message : 'Unknown'}` 
            });
        } else {
            const result = await sendMessage(session_key, phone, message, media_url, audio, mimetype, image);
            res.json({ status: 'success', data: result });
        }
    } catch (err) {
        console.error(`Error sending message via ${session_key} to ${phone}:`, err);
        res.status(500).json({ error: err.message || 'Failed to send message' });
    }
});

// Auto-start default sessions (3 slots, staggered every 20s)
async function startSlotsSequentially() {
    console.log('🔄 Auto-starting 3 WhatsApp slots sequentially...');
    const WEBHOOK_URL = 'https://otp.intaleqapp.com/api/whatsapp-webhook.php';
    for (let i = 1; i <= 3; i++) {
        console.log(`[Sequential] Starting slot-${i}...`);
        startSession(`slot-${i}`, WEBHOOK_URL).catch(err => {
            console.error(`[Sequential] slot-${i} failed:`, err.message);
        });
        if (i < 3) {
            await new Promise(resolve => setTimeout(resolve, 20000));
        }
    }
}
setTimeout(startSlotsSequentially, 2000);

app.listen(PORT, () => {
    console.log(`🚀 Flash Call OTP WhatsApp Gateway running on port ${PORT}`);
});