import nodemailer from 'nodemailer';
import handlebars from 'handlebars';
import fs from 'fs/promises';
import path from 'path';
import { fileURLToPath } from 'url';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

// Helper function to format currency with commas
function formatCurrency(amount) {
  const num = typeof amount === 'number' ? (amount / 100).toFixed(2) : parseFloat(amount).toFixed(2);
  return num.replace(/\B(?=(\d{3})+(?!\d))/g, ',');
}

// Create transporter with connection pooling
const transporter = nodemailer.createTransport({
  host: process.env.SMTP_HOST || 'mail.puffinoffset.com',
  port: parseInt(process.env.SMTP_PORT) || 587,
  secure: process.env.SMTP_SECURE === 'true', // true for 465, false for other ports
  auth: {
    user: process.env.SMTP_USER || 'noreply@puffinoffset.com',
    pass: process.env.SMTP_PASSWORD
  },
  pool: true,
  maxConnections: 5,
  maxMessages: 100,
  rateDelta: 1000,
  rateLimit: 10
});

// Verify connection configuration on startup
export async function verifyConnection() {
  try {
    await transporter.verify();
    console.log('✅ SMTP server is ready to send emails');
    return true;
  } catch (error) {
    console.error('❌ SMTP connection failed:', error.message);
    return false;
  }
}

// Load and compile template
async function loadTemplate(templateName) {
  try {
    const templatePath = path.join(__dirname, '..', 'templates', `${templateName}.hbs`);
    const templateSource = await fs.readFile(templatePath, 'utf-8');
    return handlebars.compile(templateSource);
  } catch (error) {
    console.error(`Failed to load template ${templateName}:`, error.message);
    throw new Error(`Template ${templateName} not found`);
  }
}

// Send email using template
export async function sendTemplateEmail(to, subject, templateName, data) {
  try {
    // Load and compile template
    const template = await loadTemplate(templateName);
    const html = template(data);

    // Create plain text version (strip HTML tags)
    const text = html.replace(/<[^>]*>/g, '').replace(/\s+/g, ' ').trim();

    // Send email
    const info = await transporter.sendMail({
      from: `"${process.env.SMTP_FROM_NAME || 'Puffin Offset'}" <${process.env.SMTP_FROM_EMAIL || 'noreply@puffinoffset.com'}>`,
      to,
      subject,
      text,
      html
    });

    console.log(`✉️  Email sent: ${info.messageId} to ${to}`);
    return {
      success: true,
      messageId: info.messageId,
      accepted: info.accepted,
      rejected: info.rejected
    };
  } catch (error) {
    console.error('❌ Failed to send email:', error.message);
    throw error;
  }
}

// Send receipt email
export async function sendReceiptEmail(customerEmail, orderDetails) {
  const subject = `Order Confirmation - ${orderDetails.tons} tons CO₂ Offset`;

  // Prepare template data
  const templateData = {
    tons: orderDetails.tons,
    portfolioId: orderDetails.portfolioId,
    baseAmount: formatCurrency(orderDetails.baseAmount),
    processingFee: formatCurrency(orderDetails.processingFee),
    totalAmount: formatCurrency(orderDetails.totalAmount),
    orderId: orderDetails.orderId,
    stripeSessionId: orderDetails.stripeSessionId,
    date: new Date().toLocaleDateString('en-US', {
      year: 'numeric',
      month: 'long',
      day: 'numeric'
    })
  };

  // Add portfolio projects if available
  if (orderDetails.projects && orderDetails.projects.length > 0) {
    templateData.projects = orderDetails.projects;
  }

  // Add carbon comparisons if available
  if (orderDetails.comparisons && orderDetails.comparisons.length > 0) {
    templateData.comparisons = orderDetails.comparisons;
  }

  return await sendTemplateEmail(
    customerEmail,
    subject,
    'receipt',
    templateData
  );
}

// Send contact form email
export async function sendContactEmail(contactData) {
  const subject = `Contact Form: ${contactData.name}`;
  const adminEmail = process.env.ADMIN_EMAIL || 'matt@puffinoffset.com';

  return await sendTemplateEmail(
    adminEmail,
    subject,
    'contact',
    {
      name: contactData.name,
      email: contactData.email,
      phone: contactData.phone || 'Not provided',
      company: contactData.company || 'Not provided',
      message: contactData.message,
      timestamp: new Date().toLocaleString('en-US', {
        year: 'numeric',
        month: 'long',
        day: 'numeric',
        hour: '2-digit',
        minute: '2-digit'
      })
    }
  );
}

// Send admin notification for new order
export async function sendAdminNotification(orderDetails, customerEmail) {
  // totalAmount is already in dollars (converted before calling this function)
  const totalAmount = typeof orderDetails.totalAmount === 'string'
    ? orderDetails.totalAmount
    : (orderDetails.totalAmount / 100).toFixed(2);

  // Format amount with commas for subject line
  const formattedAmount = parseFloat(totalAmount).toFixed(2).replace(/\B(?=(\d{3})+(?!\d))/g, ',');
  const subject = `New Order: ${orderDetails.tons} tons CO₂ - $${formattedAmount}`;
  const adminEmail = process.env.ADMIN_EMAIL || 'matt@puffinoffset.com';

  // Check if admin notifications are enabled
  if (process.env.ADMIN_NOTIFY_ON_ORDER === 'false') {
    console.log('ℹ️  Admin notifications disabled, skipping');
    return { success: true, skipped: true };
  }

  return await sendTemplateEmail(
    adminEmail,
    subject,
    'admin-notification',
    {
      tons: orderDetails.tons,
      portfolioId: orderDetails.portfolioId,
      totalAmount: totalAmount,
      orderId: orderDetails.orderId,
      customerEmail,
      timestamp: new Date().toLocaleString('en-US', {
        year: 'numeric',
        month: 'long',
        day: 'numeric',
        hour: '2-digit',
        minute: '2-digit'
      })
    }
  );
}

// Close transporter (for graceful shutdown)
export function closeTransporter() {
  transporter.close();
  console.log('📪 Email transporter closed');
}