require('dotenv').config({ override: true });
const express = require('express');
const crypto = require('crypto');
const { generateInvoicePDF } = require('./pdfGenerator');
const { sendEmailWithAttachment } = require('./mailer');

const app = express();
const PORT = process.env.PORT || 3000;

// Middleware to capture raw body for Shopify webhook HMAC verification
app.use(express.json({
    verify: (req, res, buf) => {
        req.rawBody = buf;
    }
}));

// Function to verify Shopify Webhook
const verifyShopifyWebhook = (req, res, next) => {
    const hmacHeader = req.get('X-Shopify-Hmac-Sha256');
    const body = req.rawBody;
    const secret = process.env.SHOPIFY_WEBHOOK_SECRET;

    if (!hmacHeader || !body || !secret) {
        return res.status(401).send('Webhook verification failed: Missing headers or secret.');
    }

    const generatedHash = crypto
        .createHmac('sha256', secret)
        .update(body, 'utf8')
        .digest('base64');

    if (generatedHash !== hmacHeader) {
        return res.status(401).send('Webhook verification failed: Invalid HMAC.');
    }

    next();
};

// Webhook endpoint for Order Creation
app.post('/webhooks/orders/create', verifyShopifyWebhook, async (req, res) => {
    const fs = require('fs');
    const logMessage = `[${new Date().toISOString()}] Received webhook request\n`;
    fs.appendFileSync('webhook.log', logMessage);

    // Acknowledge receipt of the webhook immediately
    res.status(200).send('Webhook received');

    try {
        const orderData = req.body;
        const processMessage = `[${new Date().toISOString()}] Processing Order ${orderData.order_number}\n`;
        fs.appendFileSync('webhook.log', processMessage);

        // 1. Generate the PDF invoice
        const pdfBuffer = await generateInvoicePDF(orderData);

        // 2. Send the email with the attached PDF
        const customerEmail = orderData.email || orderData.contact_email;
        if (!customerEmail) {
            const errorMsg = `[${new Date().toISOString()}] Order ${orderData.order_number} has no email address associated.\n`;
            fs.appendFileSync('webhook.log', errorMsg);
            return;
        }

        await sendEmailWithAttachment(
            customerEmail,
            orderData.order_number,
            pdfBuffer
        );

        const successMsg = `[${new Date().toISOString()}] Successfully processed and sent email for Order ${orderData.order_number}\n`;
        fs.appendFileSync('webhook.log', successMsg);

    } catch (error) {
        const errorMsg = `[${new Date().toISOString()}] Error processing order webhook: ${error.stack}\n`;
        fs.appendFileSync('webhook.log', errorMsg);
        console.error('Error processing order webhook:', error);
    }
});

app.listen(PORT, () => {
    console.log(`Shopify Invoice Email Plugin running on port ${PORT}`);
});