// services/mailer.js
// Thin nodemailer wrapper for stage-change email notifications (Production
// module). SMTP credentials come from .env (SMTP_HOST/PORT/SECURE/USER/
// PASSWORD/FROM) — there is no SMTP config in the Admin UI. Until SMTP_HOST
// is set, sendMail() is a safe no-op (logs and resolves) so the rest of the
// notification pipeline (and the request that triggered it) never breaks
// because email isn't configured yet.
'use strict';
const nodemailer = require('nodemailer');

let _transporter = null;

function isConfigured() {
  return !!process.env.SMTP_HOST;
}

function getTransporter() {
  if (_transporter) return _transporter;
  _transporter = nodemailer.createTransport({
    host: process.env.SMTP_HOST,
    port: parseInt(process.env.SMTP_PORT) || 587,
    secure: String(process.env.SMTP_SECURE).toLowerCase() === 'true',
    auth: process.env.SMTP_USER ? { user: process.env.SMTP_USER, pass: process.env.SMTP_PASSWORD } : undefined,
  });
  return _transporter;
}

const mailLog = () => require('./mailLogStore');

// Never throws — logs and resolves so a mail failure can't break the caller's
// request. Returns true if actually sent, false if skipped/failed. Every
// outcome (sent/failed/skipped) is also recorded to the Mail Log (see
// services/mailLogStore.js, viewer at /mail-logs) so delivery can be
// confirmed without digging through console output.
async function sendMail({ to, subject, html, text }) {
  const recipients = Array.isArray(to) ? to.filter(Boolean) : [to].filter(Boolean);
  if (!recipients.length) return false;
  if (!isConfigured()) {
    console.log(`[MAILER] SMTP not configured — skipping email "${subject}" to ${recipients.join(', ')}`);
    await mailLog().record({ to: recipients, subject, status: 'SKIPPED', error: 'SMTP not configured' });
    return false;
  }
  try {
    const info = await getTransporter().sendMail({
      from: process.env.SMTP_FROM || process.env.SMTP_USER,
      to: recipients.join(', '),
      subject,
      html,
      text: text || undefined,
    });
    console.log(`[MAILER] sent "${subject}" to ${recipients.join(', ')} (messageId: ${info.messageId})`);
    await mailLog().record({ to: recipients, subject, status: 'SENT', messageId: info.messageId });
    return true;
  } catch (e) {
    console.error(`[MAILER] send FAILED for "${subject}" to ${recipients.join(', ')}:`, e.message);
    await mailLog().record({ to: recipients, subject, status: 'FAILED', error: e.message });
    return false;
  }
}

// Checks the SMTP connection/credentials without sending anything — surfaces
// the real error (bad host, auth rejected, etc.) rather than a generic
// send failure.
async function verifyConnection() {
  if (!isConfigured()) return { ok: false, message: 'SMTP_HOST is not set in .env' };
  try {
    await getTransporter().verify();
    return { ok: true };
  } catch (e) {
    return { ok: false, message: e.message };
  }
}

module.exports = { sendMail, isConfigured, verifyConnection };