import { randomUUID, timingSafeEqual } from 'node:crypto'
import path from 'node:path'
import { fileURLToPath } from 'node:url'
import express from 'express'
import { JobQueue } from './jobs.js'
import { logger } from './logger.js'
import { closeBrowser } from './pdf-renderer.js'
import { WikiClient } from './wiki-client.js'
import {
  AppError,
  comparePagePaths,
  isPlainObject,
  normalizeApiKey,
  normalizeBaseUrl,
  toPositiveInt,
} from './utils.js'

const __dirname = path.dirname(fileURLToPath(import.meta.url))
const publicDir = path.join(__dirname, '..', 'public')

const PORT = toPositiveInt(process.env.PORT, 8080, { min: 1, max: 65535 })
const HOST = process.env.HOST || '0.0.0.0'
const MAX_PAGES = toPositiveInt(process.env.MAX_PAGES, 500, { min: 1, max: 5000 })
const MAX_QUEUE = toPositiveInt(process.env.MAX_QUEUE, 5, { min: 1, max: 100 })
const JOB_TTL_MS = toPositiveInt(process.env.JOB_TTL_MINUTES, 120, { min: 1, max: 1440 }) * 60 * 1000
const EXPORT_CONCURRENCY = toPositiveInt(process.env.EXPORT_CONCURRENCY, 1, { min: 1, max: 3 })
const PAGE_FETCH_CONCURRENCY = toPositiveInt(process.env.PAGE_FETCH_CONCURRENCY, 4, { min: 1, max: 12 })
const AUTH_USER = process.env.AUTH_USER || ''
const AUTH_PASSWORD = process.env.AUTH_PASSWORD || ''
// The wiki connection is configured once on the server, never sent by the
// browser and never included in job status responses or logs.
const WIKI_API_KEY = normalizeApiKey(process.env.WIKI_API_KEY)
const WIKI_URL_INPUT = String(process.env.WIKI_URL || '').trim()
let WIKI_URL = null
let WIKI_URL_ERROR = null
if (WIKI_URL_INPUT) {
  try {
    WIKI_URL = normalizeBaseUrl(WIKI_URL_INPUT)
  } catch (error) {
    WIKI_URL_ERROR = error.message
  }
}

function requireWikiConfig() {
  if (!WIKI_URL) {
    throw new AppError(
      WIKI_URL_ERROR
        ? `The wiki URL from WIKI_URL is invalid: ${WIKI_URL_ERROR}`
        : 'The Wiki.js URL is not configured on the server. Set WIKI_URL and restart the container.',
      { status: 503, code: 'WIKI_URL_MISSING' },
    )
  }
  if (!WIKI_API_KEY) {
    throw new AppError(
      'The Wiki.js API key is not configured on the server. Set WIKI_API_KEY and restart the container.',
      { status: 503, code: 'WIKI_API_KEY_MISSING' },
    )
  }
}

const app = express()
app.disable('x-powered-by')

const jobs = new JobQueue({
  concurrency: EXPORT_CONCURRENCY,
  maxQueue: MAX_QUEUE,
  ttlMs: JOB_TTL_MS,
})

app.use((req, res, next) => {
  res.setHeader('X-Content-Type-Options', 'nosniff')
  res.setHeader('Referrer-Policy', 'no-referrer')
  res.setHeader('X-Frame-Options', 'DENY')
  res.setHeader(
    'Content-Security-Policy',
    "default-src 'self'; style-src 'self' 'unsafe-inline'; script-src 'self'; img-src 'self' data:; connect-src 'self'; form-action 'self'; frame-ancestors 'none'; base-uri 'none'",
  )
  next()
})

app.use((req, res, next) => {
  const requestId = randomUUID()
  const startedAt = Date.now()
  req.requestId = requestId
  req.requestStartedAt = startedAt
  res.setHeader('X-Request-Id', requestId)

  res.on('finish', () => {
    if (res.locals.errorLogged) return
    const fields = {
      requestId,
      method: req.method,
      path: req.path,
      status: res.statusCode,
      durationMs: Date.now() - startedAt,
    }
    // The UI polls the job status every second. Keep those lines out of the
    // info log so a single export does not flood the output.
    const isJobStatusPoll =
      req.method === 'GET' && /^\/api\/exports\/[0-9a-f-]+$/i.test(req.path)

    if (res.statusCode >= 500) {
      logger.error('request failed', fields)
    } else if (res.statusCode >= 400) {
      logger.warn('request rejected', fields)
    } else if (!isJobStatusPoll && (req.path === '/' || req.path.startsWith('/api/'))) {
      logger.info('request', fields)
    } else {
      logger.debug('request', fields)
    }
  })

  next()
})

function safeEqual(left, right) {
  const leftBuffer = Buffer.from(String(left))
  const rightBuffer = Buffer.from(String(right))
  if (leftBuffer.length !== rightBuffer.length) return false
  return timingSafeEqual(leftBuffer, rightBuffer)
}

function basicAuth(req, res, next) {
  if (!AUTH_USER || !AUTH_PASSWORD) return next()

  const header = req.headers.authorization || ''
  if (header.startsWith('Basic ')) {
    const decoded = Buffer.from(header.slice(6), 'base64').toString('utf8')
    const separator = decoded.indexOf(':')
    const user = separator >= 0 ? decoded.slice(0, separator) : decoded
    const password = separator >= 0 ? decoded.slice(separator + 1) : ''
    if (safeEqual(user, AUTH_USER) && safeEqual(password, AUTH_PASSWORD)) {
      return next()
    }
  }

  res.setHeader('WWW-Authenticate', 'Basic realm="wiki-print", charset="UTF-8"')
  return res.status(401).send('Authentication required.')
}

app.get('/healthz', (req, res) => {
  res.json({ status: 'ok' })
})

app.use(basicAuth)
app.use(express.json({ limit: '256kb' }))

app.get('/api/config', (req, res) => {
  res.setHeader('Cache-Control', 'no-store')
  res.json({
    wikiUrl: WIKI_URL?.href || null,
    wikiUrlConfigured: Boolean(WIKI_URL),
    maxPages: MAX_PAGES,
    maxQueue: MAX_QUEUE,
    authEnabled: Boolean(AUTH_USER && AUTH_PASSWORD),
    apiKeyConfigured: Boolean(WIKI_API_KEY),
  })
})

app.get('/api/pages', async (req, res, next) => {
  const startedAt = Date.now()
  try {
    requireWikiConfig()

    const client = new WikiClient({
      baseUrl: WIKI_URL,
      apiKey: WIKI_API_KEY,
      logger: logger.child({ requestId: req.requestId }),
    })
    const [listedPages, localization] = await Promise.all([
      client.listPages(),
      client.getLocalization(),
    ])

    const pages = listedPages
      .map((page) => ({
        path: String(page.path || ''),
        locale: String(page.locale || ''),
        title: page.title || '',
        description: page.description || '',
        isPublished: page.isPublished !== false,
      }))
      .filter((page) => page.path && page.locale)
      .sort(
        (a, b) =>
          a.locale.localeCompare(b.locale, 'en') || comparePagePaths(a.path, b.path),
      )

    logger.info('page list loaded', {
      requestId: req.requestId,
      pageCount: pages.length,
      publishedCount: pages.filter((page) => page.isPublished).length,
      locales: [...new Set(pages.map((page) => page.locale))],
      defaultLocale: localization?.locale || null,
      durationMs: Date.now() - startedAt,
    })

    res.setHeader('Cache-Control', 'no-store')
    res.json({
      baseUrl: WIKI_URL.href,
      defaultLocale: localization?.locale || null,
      namespacing: localization?.namespacing ?? null,
      pages,
    })
  } catch (error) {
    next(error)
  }
})

app.post('/api/exports', (req, res, next) => {
  try {
    const body = req.body
    if (!isPlainObject(body)) {
      throw new AppError('Expected a JSON request body.')
    }

    requireWikiConfig()

    const startPage = String(body.startPage ?? '').trim()

    if (!startPage) throw new AppError('The starting page is required.')
    if (startPage.length > 2048) throw new AppError('The starting page is too long.')

    const locale = body.locale ? String(body.locale).trim().toLowerCase() : null
    if (locale && !/^[a-z]{2,3}(?:-[a-z0-9]{2,8})?$/.test(locale)) {
      throw new AppError('The locale is not a valid language tag (for example "en" or "de-ch").')
    }

    const maxPages = toPositiveInt(body.maxPages, MAX_PAGES, { min: 1, max: 5000 })

    const job = jobs.enqueue({
      baseUrl: WIKI_URL.href,
      apiKey: WIKI_API_KEY,
      startPage,
      locale,
      includeUnpublished: body.includeUnpublished === true,
      includeToc: body.includeToc !== false,
      inlineImages: body.inlineImages !== false,
      maxPages,
      concurrency: PAGE_FETCH_CONCURRENCY,
    })

    logger.info('export requested', {
      requestId: req.requestId,
      jobId: job.id,
      startPage,
      locale,
      maxPages,
      includeUnpublished: body.includeUnpublished === true,
      includeToc: body.includeToc !== false,
      inlineImages: body.inlineImages !== false,
    })

    res.setHeader('Cache-Control', 'no-store')
    res.status(202).json({ job })
  } catch (error) {
    next(error)
  }
})

app.get('/api/exports/:id', (req, res) => {
  const job = jobs.get(req.params.id)
  if (!job) {
    return res.status(404).json({ error: 'Export not found.' })
  }
  res.setHeader('Cache-Control', 'no-store')
  return res.json({ job })
})

app.get('/api/exports/:id/pdf', (req, res) => {
  const job = jobs.getInternal(req.params.id)
  if (!job) {
    return res.status(404).json({ error: 'Export not found.' })
  }
  if (job.status !== 'done' || !job.filePath) {
    return res.status(409).json({ error: 'The PDF is not ready yet.' })
  }

  res.setHeader('Cache-Control', 'no-store')
  res.setHeader('Content-Type', 'application/pdf')
  return res.download(job.filePath, job.result?.filename || 'wiki-export.pdf', (error) => {
    if (error && !res.headersSent) {
      res.status(404).json({ error: 'The PDF file is no longer available.' })
    }
  })
})

// The UI files have no content hashes in their names, so caching them for an
// hour means a browser can keep running an old app.js after a rebuild (for
// example one that did not load the page list). Always revalidate the HTML,
// JavaScript and CSS; static images may still be cached.
app.use(
  express.static(publicDir, {
    index: 'index.html',
    etag: true,
    lastModified: true,
    setHeaders(res, filePath) {
      if (/\.(?:html|js|css)$/i.test(filePath)) {
        res.setHeader('Cache-Control', 'no-cache')
      } else {
        res.setHeader('Cache-Control', 'public, max-age=3600')
      }
    },
  }),
)

app.use('/api', (req, res) => {
  res.status(404).json({ error: 'Not found.' })
})

app.use((req, res) => {
  res.status(404).send('Not found.')
})

app.use((error, req, res, next) => {
  if (res.headersSent) return next(error)
  const status = Number.isInteger(error.status) ? error.status : 500
  res.locals.errorLogged = true
  const fields = {
    requestId: req.requestId,
    method: req.method,
    path: req.path,
    status,
    durationMs: Date.now() - (req.requestStartedAt || Date.now()),
    code: error.code || (status >= 500 ? 'INTERNAL_ERROR' : 'BAD_REQUEST'),
    error,
  }
  if (status >= 500) {
    logger.error('request error', fields)
  } else {
    logger.warn('request rejected', { ...fields, error: error.message })
  }
  res.status(status).json({
    error: error.message || 'Internal server error.',
    code: error.code || 'INTERNAL_ERROR',
    details: error.details,
  })
})

const server = app.listen(PORT, HOST, () => {
  logger.info('server started', {
    host: HOST,
    port: PORT,
    maxPages: MAX_PAGES,
    maxQueue: MAX_QUEUE,
    exportConcurrency: EXPORT_CONCURRENCY,
    pageFetchConcurrency: PAGE_FETCH_CONCURRENCY,
    jobTtlMinutes: JOB_TTL_MS / 60_000,
    authEnabled: Boolean(AUTH_USER && AUTH_PASSWORD),
    apiKeyConfigured: Boolean(WIKI_API_KEY),
    wikiUrlConfigured: Boolean(WIKI_URL),
  })

  if (WIKI_URL) {
    logger.info('wiki configured', { wikiUrl: WIKI_URL.href })
  } else {
    logger.warn('wiki URL is not configured', {
      reason: WIKI_URL_ERROR || 'WIKI_URL is not set',
      hint: 'Set WIKI_URL and restart the container.',
    })
  }
  if (!WIKI_API_KEY) {
    logger.warn('wiki API key is not configured', {
      hint: 'Set WIKI_API_KEY and restart the container.',
    })
  }
})

let shuttingDown = false
async function shutdown(signal) {
  if (shuttingDown) return
  shuttingDown = true
  logger.info('shutting down', { signal })
  const forceTimer = setTimeout(() => process.exit(1), 15_000)
  forceTimer.unref?.()

  server.close()
  await jobs.close().catch(() => {})
  await closeBrowser().catch(() => {})
  clearTimeout(forceTimer)
  process.exit(0)
}

process.on('SIGTERM', () => shutdown('SIGTERM'))
process.on('SIGINT', () => shutdown('SIGINT'))
process.on('unhandledRejection', (error) => {
  logger.error('unhandled rejection', { error })
})

export { app, server }