import nodemailer from 'nodemailer'

const SMTP_HOST = process.env.SMTP_HOST
const SMTP_PORT = parseInt(process.env.SMTP_PORT || '587', 10)
const SMTP_USER = process.env.SMTP_USER
const SMTP_PASS = process.env.SMTP_PASS
const STAKEHOLDER_EMAIL = process.env.STAKEHOLDER_EMAIL || 'knie@d-hive.de'
const BASE_URL = process.env.BASE_URL || 'https://andreknie.de'

let transporter = null

export class MailerNotReadyError extends Error {
  constructor() {
    super('Mailer ist nicht konfiguriert.')
    this.name = 'MailerNotReadyError'
    this.code = 'MAILER_NOT_READY'
  }
}

export function isMailerReady() {
  return Boolean(SMTP_HOST && SMTP_USER && SMTP_PASS)
}

function getTransporter() {
  if (!transporter && SMTP_HOST && SMTP_USER && SMTP_PASS) {
    transporter = nodemailer.createTransport({
      host: SMTP_HOST,
      port: SMTP_PORT,
      secure: SMTP_PORT === 465,
      auth: { user: SMTP_USER, pass: SMTP_PASS },
    })
  }
  return transporter
}

export async function sendConfirmationEmail(to, type, token) {
  const t = getTransporter()
  if (!t) throw new MailerNotReadyError()

  const confirmUrl = `${BASE_URL}/api/${type}/confirm/${token}`
  const subjects = {
    contact: 'Bitte bestätige deine Kontaktanfrage',
    'talk-request': 'Bitte bestätige deine Vortragsanfrage',
    newsletter: 'Bitte bestätige dein Newsletter-Abo',
  }

  await t.sendMail({
    from: SMTP_USER,
    to,
    subject: subjects[type] || 'Bestätigung erforderlich',
    text: `Bitte bestätige deine Anfrage:\n\n${confirmUrl}\n\nDieser Link ist 48 Stunden gültig.`,
  })
}

export async function sendStakeholderNotification(type, data) {
  const t = getTransporter()
  if (!t) throw new MailerNotReadyError()

  const subjects = {
    contact: `Neue Kontaktanfrage von ${data.name}`,
    'talk-request': `Neue Vortragsanfrage von ${data.name}`,
    'resource-download': `Ressourcenanfrage von ${data.name}`,
  }

  const body = [
    'Bitte die angefragten Inhalte prüfen und bei positiver Prüfung ein aktuelles Profil von André verschicken.',
    '',
    ...Object.entries(data).map(([key, val]) => `${key}: ${val}`),
  ].join('\n')

  await t.sendMail({
    from: SMTP_USER,
    to: type === 'resource-download' ? 'kontakt@d-hive.de' : STAKEHOLDER_EMAIL,
    subject: subjects[type] || `Neue Anfrage (${type})`,
    text: body,
  })
}

export { STAKEHOLDER_EMAIL, BASE_URL }

/**
 * Send the speaker CV PDF as an attachment to the requester, and notify the
 * stakeholder about the lead. If the PDF is missing, the stakeholder is still
 * notified so the CV can be sent manually.
 * @returns {{ sent: boolean, pdfMissing: boolean }}
 */
export async function sendSpeakerCv(to, lead, pdfPath) {
  const { existsSync } = await import('fs')
  const t = getTransporter()
  const pdfMissing = !pdfPath || !existsSync(pdfPath)

  if (!t) throw new MailerNotReadyError()

  if (!pdfMissing) {
    await t.sendMail({
      from: SMTP_USER,
      to,
      subject: 'Dein Speaker CV von Dr. Andre Knie',
      text: `Hallo ${lead.name},\n\nvielen Dank für dein Interesse. Im Anhang findest du meinen Speaker CV.\n\nBeste Grüße\nAndre Knie`,
      attachments: [{ filename: 'Speaker-CV-Andre-Knie.pdf', path: pdfPath }],
    })
  }

  await notifyStakeholderSpeakerCv(lead, pdfMissing)
  return { sent: !pdfMissing, pdfMissing }
}

async function notifyStakeholderSpeakerCv(lead, pdfMissing) {
  const t = getTransporter()
  const body = [
    `Name: ${lead.name}`,
    `E-Mail: ${lead.email}`,
    `Nachricht: ${lead.message}`,
    `Zeitpunkt: ${lead.timestamp}`,
    pdfMissing
      ? 'ACHTUNG: PDF fehlte — CV wurde NICHT automatisch versandt, bitte manuell senden.'
      : 'CV wurde automatisch an den Anfragenden gesendet.',
  ].join('\n')

  if (!t) throw new MailerNotReadyError()

  await t.sendMail({
    from: SMTP_USER,
    to: STAKEHOLDER_EMAIL,
    subject: `Speaker-CV-Anfrage von ${lead.name}`,
    text: body,
  })
}