/**
 * PDF Generation Service
 * Handles HTML to PDF conversion using Puppeteer
 */
const path = require('path');
const fs = require('fs').promises;
const { formatMoney, formatDate } = require('../utils/helpers');

// Initialize browser - will be set from main app
let browserInstance = null;

function setBrowser(browser) {
    browserInstance = browser;
}

async function getBrowser() {
    return browserInstance;
}

/**
 * Generate PDF from HTML template
 */
async function generatePdfFromHtml(html, options = {}) {
    const {
        format = 'Letter',
        margin = { top: '0.5in', right: '0.5in', bottom: '0.5in', left: '0.5in' },
        printBackground = true
    } = options;

    const browser = await getBrowser();
    if (!browser) {
        throw new Error('Browser not initialized');
    }

    const page = await browser.newPage();
    
    try {
        // Erhöhtes Timeout: 5 Sekunden sind unter Docker manchmal zu wenig.
        // Besser auf 15 Sekunden (15000) setzen, um den Fehler von vornherein zu vermeiden.
        await page.setContent(html, { waitUntil: 'load', timeout: 15000 });

        const pdf = await page.pdf({
            format,
            printBackground,
            margin
        });
        
        return pdf;
    } finally {
        // Dieser Block wird IMMER ausgeführt, selbst wenn oben ein Fehler fliegt.
        // Der Tab wird also zu 100% wieder geschlossen.
        if (page) {
            await page.close();
        }
    }
}

/**
 * Get company logo as base64 HTML
 */
async function getLogoHtml() {
    let logoHTML = '';
    try {
        const logoPath = path.join(__dirname, '..', '..', 'public', 'uploads', 'company-logo.png');
        const logoData = await fs.readFile(logoPath);
        const logoBase64 = logoData.toString('base64');
        logoHTML = `<img src="data:image/png;base64,${logoBase64}" alt="Company Logo" class="logo logo-size">`;
    } catch (err) {
        // No logo found
    }
    return logoHTML;
}

/**
 * Render invoice items to HTML table rows
 */
function renderInvoiceItems(items, invoice = null) {
    let itemsHTML = items.map(item => {
        let rateFormatted = item.rate;
        if (item.rate.toUpperCase() !== 'TBD' && !item.rate.includes('/')) {
            const rateNum = parseFloat(item.rate.replace(/[^0-9.]/g, ''));
            if (!isNaN(rateNum)) rateFormatted = rateNum.toFixed(2);
        }
        return `
        <tr>
            <td class="qty">${item.quantity}</td>
            <td class="description">${item.description}</td>
            <td class="rate">${rateFormatted}</td>
            <td class="amount">${item.amount}</td>
        </tr>`;
    }).join('');
    
    // Add subtotal
    const subtotal = invoice ? invoice.subtotal : 0;
    itemsHTML += `
        <tr class="footer-row">
            <td colspan="3" class="total-label">Subtotal:</td>
            <td class="total-amount">$${formatMoney(subtotal)}</td>
        </tr>`;
    
    // Add tax if not exempt
    if (invoice && !invoice.tax_exempt) {
        itemsHTML += `
        <tr class="footer-row">
            <td colspan="3" class="total-label">Tax (${invoice.tax_rate}%):</td>
            <td class="total-amount">$${formatMoney(invoice.tax_amount)}</td>
        </tr>`;
    }
    
    // Add total
    const amountPaid = invoice ? (parseFloat(invoice.amount_paid) || 0) : 0;
    const total = invoice ? parseFloat(invoice.total) : 0;
    const balanceDue = total - amountPaid;
    
    itemsHTML += `
        <tr class="footer-row">
            <td colspan="3" class="total-label" style="font-size: 16px;">TOTAL:</td>
            <td class="total-amount" style="font-size: 16px;">$${formatMoney(total)}</td>
        </tr>`;
    
    // Add downpayment/balance if partial
    // Add downpayment/balance if partial
    if (amountPaid > 0) {
        const isFullyPaid = balanceDue <= 0.01; // allow for rounding
        const paymentLabel = isFullyPaid ? 'Payment:' : 'Downpayment:';
        
        itemsHTML += `
        <tr class="footer-row">
            <td colspan="3" class="total-label" style="color: #059669;">${paymentLabel}</td>
            <td class="total-amount" style="color: #059669;">-$${formatMoney(amountPaid)}</td>
        </tr>`;

        // Only show BALANCE DUE row if there's actually a remaining balance
        if (!isFullyPaid) {
            itemsHTML += `
        <tr class="footer-row">
            <td colspan="3" class="total-label" style="font-weight: bold; font-size: 16px; border-top: 2px solid #333; padding-top: 8px;">BALANCE DUE:</td>
            <td class="total-amount" style="font-weight: bold; font-size: 16px; border-top: 2px solid #333; padding-top: 8px;">$${formatMoney(balanceDue)}</td>
        </tr>`;
        }
    }
    
    // Thank you message
    itemsHTML += `
        <tr class="footer-row">
            <td colspan="4" class="thank-you">Thank you for your business!</td>
        </tr>`;
    
    return itemsHTML;
}

/**
 * Render quote items to HTML table rows
 */
function renderQuoteItems(items, quote = null) {
    let itemsHTML = items.map(item => {
        let rateFormatted = item.rate;
        if (item.rate.toUpperCase() !== 'TBD' && !item.rate.includes('/')) {
            const rateNum = parseFloat(item.rate.replace(/[^0-9.]/g, ''));
            if (!isNaN(rateNum)) rateFormatted = rateNum.toFixed(2);
        }
        return `
        <tr>
            <td class="qty">${item.quantity}</td>
            <td class="description">${item.description}</td>
            <td class="rate">${rateFormatted}</td>
            <td class="amount">${item.amount}</td>
        </tr>`;
    }).join('');
    
    // Add subtotal
    const subtotal = quote ? quote.subtotal : 0;
    itemsHTML += `
        <tr class="footer-row">
            <td colspan="3" class="total-label">Subtotal</td>
            <td class="total-amount">$${formatMoney(subtotal)}</td>
        </tr>`;
    
    // Add tax if not exempt
    if (quote && !quote.tax_exempt) {
        itemsHTML += `
        <tr class="footer-row">
            <td colspan="3" class="total-label">Tax (${quote.tax_rate}%)</td>
            <td class="total-amount">$${formatMoney(quote.tax_amount)}</td>
        </tr>`;
    }
    
    // Add total
    const total = quote ? quote.total : 0;
    itemsHTML += `
        <tr class="footer-row">
            <td colspan="3" class="total-label" style="font-size: 16px;">TOTAL</td>
            <td class="total-amount" style="font-size: 16px;">$${formatMoney(total)}</td>
        </tr>
        <tr class="footer-row">
            <td colspan="4" class="thank-you">This quote is valid for 14 days. We appreciate your business </td>
        </tr>`;
    
    return itemsHTML;
}

/**
 * Format address lines for template
 */
function formatAddressLines(line1, line2, line3, line4, customerName) {
    const addressLines = [];
    if (line1 && line1.trim().toLowerCase() !== (customerName || '').trim().toLowerCase()) {
        addressLines.push(line1);
    }
    if (line2) addressLines.push(line2);
    if (line3) addressLines.push(line3);
    if (line4) addressLines.push(line4);
    return addressLines.join('<br>');
}

module.exports = {
    setBrowser,
    getBrowser,
    generatePdfFromHtml,
    getLogoHtml,
    renderInvoiceItems,
    renderQuoteItems,
    formatAddressLines
};