import nodemailer from 'nodemailer';

export default async function handler(req, res) {
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'POST, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type');

  if (req.method === 'OPTIONS') {
    return res.status(200).end();
  }

  if (req.method !== 'POST') {
    return res.status(405).json({ error: 'Method Not Allowed' });
  }

  const { type, name, email, phone, mobile, subject, message, interests, turnstileToken } = req.body;

  const contactName = name?.trim();
  const contactEmail = email?.trim();
  const contactPhone = (phone || mobile || '').trim();
  const contactSubject = (subject || interests || type || 'General Inquiry').trim();
  const contactMessage = (message || req.body.comments || '').trim();

  if (!contactName || !contactEmail) {
    return res.status(400).json({ error: 'Name and Email are required.' });
  }

  // Verify Cloudflare Turnstile Token
  if (turnstileToken) {
    const secretKey = process.env.TURNSTILE_SECRET_KEY || '1x000000000000000000000000000000AA';
    try {
      const formData = new URLSearchParams();
      formData.append('secret', secretKey);
      formData.append('response', turnstileToken);
      const turnstileRes = await fetch('https://challenges.cloudflare.com/turnstile/v0/siteverify', {
        method: 'POST',
        body: formData
      });
      const turnstileOutcome = await turnstileRes.json();
      if (!turnstileOutcome.success) {
        return res.status(400).json({ error: 'Cloudflare Turnstile verification failed. Please try again.' });
      }
    } catch (err) {
      console.error('Turnstile verification error:', err);
    }
  }

  // 1. Try sending via SMTP (nodemailer)
  const smtpHost = process.env.SMTP_HOST;
  const smtpUser = process.env.SMTP_USER;
  const smtpPass = process.env.SMTP_PASS;

  if (smtpHost && smtpUser && smtpPass) {
    try {
      const port = parseInt(process.env.SMTP_PORT || '465', 10);
      const secure = process.env.SMTP_SECURE === 'true' || port === 465;

      const transporter = nodemailer.createTransport({
        host: smtpHost,
        port,
        secure,
        auth: { user: smtpUser, pass: smtpPass },
        tls: { rejectUnauthorized: false }
      });

      const toEmail = process.env.SMTP_TO || smtpUser;
      const fromEmail = process.env.SMTP_FROM || `"Cavin Infotech Contact" <${smtpUser}>`;

      const info = await transporter.sendMail({
        from: fromEmail,
        to: toEmail,
        replyTo: `"${contactName}" <${contactEmail}>`,
        subject: `[Contact Form] ${contactSubject}`,
        text: `Name: ${contactName}\nEmail: ${contactEmail}\nPhone: ${contactPhone}\nSubject: ${contactSubject}\n\nMessage:\n${contactMessage}`,
        html: `
          <div style="font-family: Arial, sans-serif; background: #020710; color: #fff; padding: 30px; border-radius: 12px;">
            <h2 style="color: #ffaa00; margin-top: 0;">Cavin Infotech - Contact Inquiry</h2>
            <p><strong>Name:</strong> ${contactName}</p>
            <p><strong>Email:</strong> <a href="mailto:${contactEmail}" style="color: #38bdf8;">${contactEmail}</a></p>
            <p><strong>Phone:</strong> ${contactPhone || 'Not provided'}</p>
            <p><strong>Subject:</strong> ${contactSubject}</p>
            <div style="margin-top: 20px; padding: 15px; background: #0b1528; border-left: 4px solid #ffaa00; border-radius: 6px;">
              <p style="margin: 0; white-space: pre-line;">${contactMessage}</p>
            </div>
          </div>
        `
      });

      return res.status(200).json({ success: true, messageId: info.messageId, message: 'Message sent via SMTP!' });
    } catch (smtpErr) {
      console.error('SMTP Send Error:', smtpErr);
      return res.status(500).json({ error: `SMTP Send Error: ${smtpErr.message}` });
    }
  }

  // 2. Fallback to EmailJS API if SMTP env vars are not set
  const serviceId = process.env.EMAILJS_SERVICE_ID || 'vishva_cavintest';
  const publicKey = process.env.EMAILJS_PUBLIC_KEY || 'YOUR_EMAILJS_PUBLIC_KEY';
  const templateId = process.env.EMAILJS_TEMPLATE_ID_STRATEGY || 'YOUR_EMAILJS_TEMPLATE_ID_STRATEGY';

  try {
    const response = await fetch('https://api.emailjs.com/api/v1.0/email/send', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        service_id: serviceId,
        template_id: templateId,
        user_id: publicKey,
        template_params: {
          name: contactName,
          email: contactEmail,
          phone: contactPhone,
          interests: contactSubject,
          message: contactMessage
        }
      }),
    });

    const data = await response.text();
    if (!response.ok) {
      return res.status(response.status).json({ error: data });
    }
    return res.status(200).json({ success: true, message: data });
  } catch (error) {
    return res.status(500).json({ error: error.message });
  }
}