const nodemailer = require("nodemailer");
const { NotificationTemplate } = require("../models"); // adjust path if needed
const logger = require("../services/logger");
require("dotenv").config();
const { sanitizeForLog } = require("../utils/sanitize");

const port = Number(process.env.MAIL_PORT);

const transporter = nodemailer.createTransport({
  host: process.env.MAIL_HOST,
  port,
  secure: port === 465,   // SSL
  requireTLS: port === 587,  // Enforce TLS for 587
  auth: {
    user: process.env.MAIL_USER,
    pass: process.env.MAIL_PASS,
  },
});


/**
 * Replace placeholders in template HTML with actual data
 */
// function replacePlaceholders(templateHtml, data) {
//   let html = templateHtml;
//   for (const key in data) {
//     const regex = new RegExp(`{{\\s*${key}\\s*}}`, "g");
//     html = html.replace(regex, data[key]);
//   }
//   return html;
// }

function replacePlaceholders(templateHtml, data) {
  if(!templateHtml) return "";
  let html = templateHtml;
  
  for (const key in data) {
    const safeValue = data[key] ?? "";
    const regex = new RegExp(`{{\\s*${key}\\s*}}`, "g");
    html = html.replace(regex, safeValue);
  }

  return html;
}



exports.sendEmailService = async (to, templateCode, data = {}) => {

  const sanitizedTo = sanitizeForLog(to);
  const sanitizedTemplate = sanitizeForLog(templateCode);
   const sanitizedData = sanitizeForLog(
    typeof data === "object" ? JSON.stringify(data) : String(data)
  );

  const logPrefix = `[EMAIL SERVICE][${new Date().toISOString()}]`;

  logger.info(`${logPrefix} → Starting email process`);
  logger.info(`${logPrefix} → Template Code: ${sanitizedTemplate}`);
  logger.info(`${logPrefix} → Recipient: ${sanitizedTo}`);
  logger.info(`${logPrefix} → Placeholder Data: ${sanitizedData}`);
  
    try {
      // 1. Fetch template from DB
      const template = await NotificationTemplate.findOne({
        where: { template_code: templateCode },
      });
  
      if (!template) {
        logger.error(`${logPrefix} ❌ Template not found for code:${sanitizedTemplate}`);
        throw new Error(`Template not found for code: ${templateCode}`);
      }
  
      // 2. Replace placeholders
      const html = replacePlaceholders(template.body_html, data);
  
      // 3. Prepare mail options
      const mailOptions = {
        from: process.env.SMTP_FROM || process.env.SMTP_USER,
        to,
        subject: template.subject || "Notification",
        html,
      };
      
  
      logger.info(`${logPrefix} ✉️ Sending email using SMTP...`);
  
      // 4. Send mail
      const info = await transporter.sendMail(mailOptions);
  
      logger.info(`${logPrefix} ✅ Email sent successfully`);
      logger.info(`${logPrefix} Message ID:  ${sanitizeForLog(info.messageId)}`);
      logger.info(`${logPrefix} Response: ${info.response}`);
  
      return {
        status: "ok",
        message: "Email sent successfully",
        messageId: info.messageId,
        response: info.response,
        to,
        subject: template.subject,
        templateCode,
      };
  
    } catch (err) {
      logger.error(`${logPrefix} ❌ Email sending failed`);
      logger.error(`${logPrefix} Error: ${err.message}`);
      if (err.stack) logger.error(`${logPrefix} Stack: ${err.stack}`);
  
      return {
        status: "failed",
        message: err.message,
        templateCode,
        to,
        error: err.stack || err.message,
      };
    }
  };