let nodemailer = null
try {
  nodemailer = require('nodemailer')
} catch (error) {
  console.warn('[emailService] nodemailer not installed:', error.message)
}

let transporter = null

function getTransporter () {
  if (!nodemailer) return null
  if (transporter) return transporter

  const host = process.env.SMTP_HOST
  const port = Number(process.env.SMTP_PORT || 587)
  const user = process.env.SMTP_USER
  const pass = process.env.SMTP_PASS

  if (!host || !user || !pass) {
    return null
  }

  transporter = nodemailer.createTransport({
    host,
    port,
    secure: port === 465,
    auth: { user, pass }
  })

  return transporter
}

function isEmailConfigured () {
  return Boolean(nodemailer && getTransporter())
}

async function sendEmail ({ to, subject, text, html }) {
  const mailer = getTransporter()
  if (!mailer) {
    console.warn('[emailService] SMTP is not configured. Email not sent to:', to)
    return false
  }

  await mailer.sendMail({
    from: process.env.SMTP_FROM || process.env.SMTP_USER,
    to,
    subject,
    text,
    html
  })

  return true
}

async function sendOtpEmail (to, otp, purpose = 'verification') {
  const subjectMap = {
    verification: 'کد تایید مدستاگرام',
    password_reset: 'بازیابی کلمه عبور مدستاگرام'
  }

  const subject = subjectMap[purpose] || subjectMap.verification
  const text = `کد تایید شما: ${otp}\n\nاین کد تا ۲ دقیقه معتبر است.\nمدستاگرام`
  const html = `
    <div dir="rtl" style="font-family:Tahoma,sans-serif;line-height:1.8">
      <h2>${subject}</h2>
      <p>کد تایید شما:</p>
      <p style="font-size:24px;font-weight:bold;letter-spacing:4px">${otp}</p>
      <p>این کد تا ۲ دقیقه معتبر است.</p>
      <p>مدستاگرام</p>
    </div>
  `

  return sendEmail({ to, subject, text, html })
}

module.exports = {
  isEmailConfigured,
  sendEmail,
  sendOtpEmail
}