const PDFDocument = require('pdfkit');

/**
 * Generates a PDF invoice based on Shopify order data.
 * @param {Object} orderData - The Shopify order payload
 * @returns {Promise<Buffer>} - A promise that resolves to a Buffer containing the PDF data
 */
const generateInvoicePDF = (orderData) => {
    return new Promise((resolve, reject) => {
        try {
            const doc = new PDFDocument({ margin: 50 });
            let buffers = [];

            doc.on('data', buffers.push.bind(buffers));
            doc.on('end', () => {
                const pdfData = Buffer.concat(buffers);
                resolve(pdfData);
            });

            // Invoice Header
            doc.fontSize(20).text('Invoice', { align: 'right' });
            doc.moveDown();

            doc.fontSize(12)
                .text(`Order Number: ${orderData.name || orderData.order_number}`)
                .text(`Date: ${new Date(orderData.created_at).toLocaleDateString()}`)
                .moveDown();

            // Store Info (You can customize this)
            const shopName = process.env.SHOP_NAME || 'Your Store Name';
            doc.fontSize(14).text(shopName);
            doc.moveDown();

            // Customer Info
            doc.fontSize(14).text('Billed To:');
            doc.fontSize(12).text(`${orderData.billing_address?.first_name || ''} ${orderData.billing_address?.last_name || ''}`);
            doc.text(`${orderData.billing_address?.address1 || ''}`);
            if (orderData.billing_address?.address2) {
                doc.text(`${orderData.billing_address.address2}`);
            }
            doc.text(`${orderData.billing_address?.city || ''}, ${orderData.billing_address?.province || ''} ${orderData.billing_address?.zip || ''}`);
            doc.text(`${orderData.billing_address?.country || ''}`);
            doc.moveDown(2);

            // Line Items Table Header
            doc.fontSize(12).font('Helvetica-Bold');
            doc.text('Item', 50, doc.y, { continued: true });
            doc.text('Qty', 300, doc.y, { continued: true, width: 50, align: 'right' });
            doc.text('Price', 350, doc.y, { continued: true, width: 100, align: 'right' });
            doc.text('Total', 450, doc.y, { width: 100, align: 'right' });
            
            doc.moveTo(50, doc.y).lineTo(550, doc.y).stroke();
            doc.moveDown(0.5);

            // Line Items Table Rows
            doc.font('Helvetica');
            let currentY = doc.y;
            
            if (orderData.line_items && orderData.line_items.length > 0) {
                orderData.line_items.forEach(item => {
                    doc.text(item.name, 50, currentY, { width: 250 });
                    doc.text(item.quantity.toString(), 300, currentY, { width: 50, align: 'right' });
                    doc.text(`${orderData.currency} ${parseFloat(item.price).toFixed(2)}`, 350, currentY, { width: 100, align: 'right' });
                    const total = parseFloat(item.price) * item.quantity;
                    doc.text(`${orderData.currency} ${total.toFixed(2)}`, 450, currentY, { width: 100, align: 'right' });
                    
                    doc.moveDown(0.5);
                    currentY = doc.y;
                });
            }

            doc.moveTo(50, currentY).lineTo(550, currentY).stroke();
            doc.moveDown(1);

            // Totals
            doc.text(`Subtotal: ${orderData.currency} ${orderData.subtotal_price}`, { align: 'right' });
            if (orderData.total_tax > 0) {
                doc.text(`Tax: ${orderData.currency} ${orderData.total_tax}`, { align: 'right' });
            }
            doc.text(`Shipping: ${orderData.currency} ${orderData.total_shipping_price_set?.shop_money?.amount || '0.00'}`, { align: 'right' });
            doc.font('Helvetica-Bold').text(`Total: ${orderData.currency} ${orderData.total_price}`, { align: 'right' });

            doc.end();
        } catch (error) {
            reject(error);
        }
    });
};

module.exports = { generateInvoicePDF };