/***********************************************************************************************************************************************************************
 * File Name: email.service.js
 * Type of Program: Service
 * Description: Nodemailer-based email service.
 *              Provides:
 *              - sendOTPEmail()    → sends a 6-digit OTP verification email
 *              - sendWelcomeEmail() → sent after successful email verification
 * Author: rgrgogu
 * Date Created: Oct. 6, 2025
 ***********************************************************************************************************************************************************************
 * HOW TO USE:
 *   const emailService = require('../services/email.service');
 *   await emailService.sendOTPEmail(user.email, otp);
 ***********************************************************************************************************************************************************************/
const nodemailer = require('nodemailer');
const { emailTemplates } = require('../data/email_body.data')

const transporter = nodemailer.createTransport({
  host: process.env.SMTP_HOST,
  port: Number(process.env.SMTP_PORT),
  auth: {
    user: process.env.SMTP_USER,
    pass: process.env.SMTP_PASS,
  },
});

const buildEmailTemplate = ({ title, body }) => {
  return `
  <div style="font-family:Arial,sans-serif;max-width:520px;margin:auto;border:1px solid #e5e7eb;border-radius:10px;overflow:hidden">

    <!-- LOGO -->
    <div style="padding:20px;text-align:center;background:#232f3e">
      <img src="${process.env.APP_LOGO_URL}" alt="Philproperties" style="height:42px" />
    </div>

    <!-- CONTENT -->
    <div style="padding:26px">
      <h2 style="color:#111827;margin-bottom:14px">${title}</h2>
      ${body}

      <!-- FORMAL CLOSING -->
      <div style="margin-top:24px">
        <p style="margin:0">Regards,</p>
        <p style="margin:4px 0 0;font-weight:600;color:#111827">
          Philproperties IT Team
        </p>
      </div>
    </div>

    <!-- FOOTER -->
    <div style="padding:14px;text-align:center;font-size:12px;color:#6b7280;border-top:1px solid #e5e7eb">
      This is an automated message from STARR System. Please do not reply.
    </div>

  </div>
  `;
};

/**
 * Sends a 6-digit OTP to the given email address.
 * @param {string} to     - recipient email
 * @param {string} otp    - 6-digit code
 * @param {number} expiryMinutes
 */
const sendEmail = async ({ to, type, data = {} }) => {
  try {
    const templateFn = emailTemplates[type];

    if (!templateFn) {
      throw new Error(`Email template "${type}" not found`);
    }

    const { subject, title, body } = templateFn(data);

    const html = buildEmailTemplate({ title, body });

    return await new Promise((resolve, reject) => {
      transporter.sendMail(
        {
          from: {
            name: "STARR System",
            address: "do-not-reply@philproperties.com",
          },
          to,
          subject,
          html,
        },
        (err, info) => {
          if (err) return reject(err);
          resolve(info);
        }
      );
    });
  } catch (err) {
    throw new Error(err.message);
  }
};

module.exports = sendEmail;