import { Router } from 'express'
import { readFileSync, writeFileSync, existsSync } from 'fs'
import { join, dirname } from 'path'
import { fileURLToPath } from 'url'
import { Mutex } from 'async-mutex'
import { resourceLimiter } from '../middleware/rateLimiter.js'
import { antiSpam } from '../middleware/antiSpam.js'
import { sendSpeakerCv } from '../services/mailer.js'

const __dirname = dirname(fileURLToPath(import.meta.url))
const LEADS_FILE = join(__dirname, '..', 'data', 'speaker-cv-leads.json')
const PDF_PATH = join(__dirname, '..', '..', 'public', 'resources', 'speaker-cv-andre-knie.pdf')
const leadsMutex = new Mutex()

function loadLeads() {
  if (!existsSync(LEADS_FILE)) return []
  try { return JSON.parse(readFileSync(LEADS_FILE, 'utf-8')) }
  catch { return [] }
}

function saveLeads(leads) {
  writeFileSync(LEADS_FILE, JSON.stringify(leads, null, 2), 'utf-8')
}

const router = Router()

router.post('/', resourceLimiter, antiSpam, async (req, res) => {
  const { name, email, message } = req.body
  const errors = {}
  if (!name || name.trim().length === 0) errors.name = 'Name ist erforderlich.'
  if (name && name.length > 100) errors.name = 'Max. 100 Zeichen.'
  if (!email || !/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email)) errors.email = 'Gültige E-Mail erforderlich.'
  if (!message || message.trim().length === 0) errors.message = 'Bitte sag kurz, wer du bist.'
  if (message && message.length > 2000) errors.message = 'Max. 2000 Zeichen.'

  if (Object.keys(errors).length > 0) {
    return res.status(400).json({ errors })
  }

  const lead = { name, email, message, timestamp: new Date().toISOString() }
  await leadsMutex.runExclusive(async () => {
    const leads = loadLeads()
    leads.push(lead)
    saveLeads(leads)
  })

  await sendSpeakerCv(email, lead, PDF_PATH)

  res.status(201).json({ ok: true, message: 'Danke! Der Speaker CV ist auf dem Weg in dein Postfach.' })
})

export default router