import { decode, encode } from 'bencode'
import createTorrent from 'create-torrent'
import { createWriteStream, ensureDir, readFile, remove, writeFile } from 'fs-extra'
import magnetUtil from 'magnet-uri'
import parseTorrent from 'parse-torrent'
import { dirname, join } from 'path'
import { pipeline } from 'stream'
import WebTorrent, { Instance, TorrentFile } from 'webtorrent'
import { isArray } from '@server/helpers/custom-validators/misc'
import { WEBSERVER } from '@server/initializers/constants'
import { generateTorrentFileName } from '@server/lib/paths'
import { VideoPathManager } from '@server/lib/video-path-manager'
import { MVideo } from '@server/types/models/video/video'
import { MVideoFile, MVideoFileRedundanciesOpt } from '@server/types/models/video/video-file'
import { MStreamingPlaylistVideo } from '@server/types/models/video/video-streaming-playlist'
import { CONFIG } from '../initializers/config'
import { promisify2 } from './core-utils'
import { sha1 } from '@shared/core-utils/crypto'
import { logger } from './logger'
import { generateVideoImportTmpPath } from './utils'
import { extractVideo } from './video'

const createTorrentPromise = promisify2<string, any, any>(createTorrent)

async function downloadWebTorrentVideo (target: { uri: string, torrentName?: string }, timeout: number) {
  const id = target.uri || target.torrentName
  let timer

  const path = generateVideoImportTmpPath(id)
  logger.info('Importing torrent video %s', id)

  const directoryPath = join(CONFIG.STORAGE.TMP_DIR, 'webtorrent')
  await ensureDir(directoryPath)

  return new Promise<string>((res, rej) => {
    const webtorrent = new WebTorrent()
    let file: TorrentFile

    const torrentId = target.uri || join(CONFIG.STORAGE.TORRENTS_DIR, target.torrentName)

    const options = { path: directoryPath }
    const torrent = webtorrent.add(torrentId, options, torrent => {
      if (torrent.files.length !== 1) {
        if (timer) clearTimeout(timer)

        for (const file of torrent.files) {
          deleteDownloadedFile({ directoryPath, filepath: file.path })
        }

        return safeWebtorrentDestroy(webtorrent, torrentId, undefined, target.torrentName)
          .then(() => rej(new Error('Cannot import torrent ' + torrentId + ': there are multiple files in it')))
      }

      logger.debug('Got torrent from webtorrent %s.', id, { infoHash: torrent.infoHash })

      file = torrent.files[0]

      // FIXME: avoid creating another stream when https://github.com/webtorrent/webtorrent/issues/1517 is fixed
      const writeStream = createWriteStream(path)
      writeStream.on('finish', () => {
        if (timer) clearTimeout(timer)

        safeWebtorrentDestroy(webtorrent, torrentId, { directoryPath, filepath: file.path }, target.torrentName)
          .then(() => res(path))
          .catch(err => logger.error('Cannot destroy webtorrent.', { err }))
      })

      pipeline(
        file.createReadStream(),
        writeStream,
        err => {
          if (err) rej(err)
        }
      )
    })

    torrent.on('error', err => rej(err))

    timer = setTimeout(() => {
      const err = new Error('Webtorrent download timeout.')

      safeWebtorrentDestroy(webtorrent, torrentId, file ? { directoryPath, filepath: file.path } : undefined, target.torrentName)
        .then(() => rej(err))
        .catch(destroyErr => {
          logger.error('Cannot destroy webtorrent.', { err: destroyErr })
          rej(err)
        })

    }, timeout)
  })
}

function createTorrentAndSetInfoHash (videoOrPlaylist: MVideo | MStreamingPlaylistVideo, videoFile: MVideoFile) {
  const video = extractVideo(videoOrPlaylist)

  const options = {
    // Keep the extname, it's used by the client to stream the file inside a web browser
    name: buildInfoName(video, videoFile),
    createdBy: 'PeerTube',
    announceList: buildAnnounceList(),
    urlList: buildUrlList(video, videoFile)
  }

  return VideoPathManager.Instance.makeAvailableVideoFile(videoFile.withVideoOrPlaylist(videoOrPlaylist), async videoPath => {
    const torrentContent = await createTorrentPromise(videoPath, options)

    const torrentFilename = generateTorrentFileName(videoOrPlaylist, videoFile.resolution)
    const torrentPath = join(CONFIG.STORAGE.TORRENTS_DIR, torrentFilename)
    logger.info('Creating torrent %s.', torrentPath)

    await writeFile(torrentPath, torrentContent)

    // Remove old torrent file if it existed
    if (videoFile.hasTorrent()) {
      await remove(join(CONFIG.STORAGE.TORRENTS_DIR, videoFile.torrentFilename))
    }

    const parsedTorrent = parseTorrent(torrentContent)
    videoFile.infoHash = parsedTorrent.infoHash
    videoFile.torrentFilename = torrentFilename
  })
}

async function updateTorrentMetadata (videoOrPlaylist: MVideo | MStreamingPlaylistVideo, videoFile: MVideoFile) {
  const video = extractVideo(videoOrPlaylist)

  const oldTorrentPath = join(CONFIG.STORAGE.TORRENTS_DIR, videoFile.torrentFilename)

  const torrentContent = await readFile(oldTorrentPath)
  const decoded = decode(torrentContent)

  decoded['announce-list'] = buildAnnounceList()
  decoded.announce = decoded['announce-list'][0][0]

  decoded['url-list'] = buildUrlList(video, videoFile)

  decoded.info.name = buildInfoName(video, videoFile)
  decoded['creation date'] = Math.ceil(Date.now() / 1000)

  const newTorrentFilename = generateTorrentFileName(videoOrPlaylist, videoFile.resolution)
  const newTorrentPath = join(CONFIG.STORAGE.TORRENTS_DIR, newTorrentFilename)

  logger.info('Updating torrent metadata %s -> %s.', oldTorrentPath, newTorrentPath)

  await writeFile(newTorrentPath, encode(decoded))
  await remove(join(CONFIG.STORAGE.TORRENTS_DIR, videoFile.torrentFilename))

  videoFile.torrentFilename = newTorrentFilename
  videoFile.infoHash = sha1(encode(decoded.info))
}

function generateMagnetUri (
  video: MVideo,
  videoFile: MVideoFileRedundanciesOpt,
  trackerUrls: string[]
) {
  const xs = videoFile.getTorrentUrl()
  const announce = trackerUrls
  let urlList = [ videoFile.getFileUrl(video) ]

  const redundancies = videoFile.RedundancyVideos
  if (isArray(redundancies)) urlList = urlList.concat(redundancies.map(r => r.fileUrl))

  const magnetHash = {
    xs,
    announce,
    urlList,
    infoHash: videoFile.infoHash,
    name: video.name
  }

  return magnetUtil.encode(magnetHash)
}

// ---------------------------------------------------------------------------

export {
  createTorrentPromise,
  updateTorrentMetadata,
  createTorrentAndSetInfoHash,
  generateMagnetUri,
  downloadWebTorrentVideo
}

// ---------------------------------------------------------------------------

function safeWebtorrentDestroy (
  webtorrent: Instance,
  torrentId: string,
  downloadedFile?: { directoryPath: string, filepath: string },
  torrentName?: string
) {
  return new Promise<void>(res => {
    webtorrent.destroy(err => {
      // Delete torrent file
      if (torrentName) {
        logger.debug('Removing %s torrent after webtorrent download.', torrentId)
        remove(torrentId)
          .catch(err => logger.error('Cannot remove torrent %s in webtorrent download.', torrentId, { err }))
      }

      // Delete downloaded file
      if (downloadedFile) deleteDownloadedFile(downloadedFile)

      if (err) logger.warn('Cannot destroy webtorrent in timeout.', { err })

      return res()
    })
  })
}

function deleteDownloadedFile (downloadedFile: { directoryPath: string, filepath: string }) {
  // We want to delete the base directory
  let pathToDelete = dirname(downloadedFile.filepath)
  if (pathToDelete === '.') pathToDelete = downloadedFile.filepath

  const toRemovePath = join(downloadedFile.directoryPath, pathToDelete)

  logger.debug('Removing %s after webtorrent download.', toRemovePath)
  remove(toRemovePath)
    .catch(err => logger.error('Cannot remove torrent file %s in webtorrent download.', toRemovePath, { err }))
}

function buildAnnounceList () {
  return [
    [ WEBSERVER.WS + '://' + WEBSERVER.HOSTNAME + ':' + WEBSERVER.PORT + '/tracker/socket' ],
    [ WEBSERVER.URL + '/tracker/announce' ]
  ]
}

function buildUrlList (video: MVideo, videoFile: MVideoFile) {
  return [ videoFile.getFileUrl(video) ]
}

function buildInfoName (video: MVideo, videoFile: MVideoFile) {
  return `${video.name} ${videoFile.resolution}p${videoFile.extname}`
}