import { close, ensureDir, move, open, outputJSON, read, readFile, remove, stat, writeFile } from 'fs-extra'
import { flatten, uniq } from 'lodash'
import PQueue from 'p-queue'
import { basename, dirname, join } from 'path'
import { MStreamingPlaylist, MStreamingPlaylistFilesVideo, MVideo } from '@server/types/models'
import { sha256 } from '@shared/extra-utils'
import { VideoStorage } from '@shared/models'
import { getAudioStreamCodec, getVideoStreamCodec, getVideoStreamDimensionsInfo } from '../helpers/ffmpeg'
import { logger } from '../helpers/logger'
import { doRequest, doRequestAndSaveToFile } from '../helpers/requests'
import { generateRandomString } from '../helpers/utils'
import { CONFIG } from '../initializers/config'
import { P2P_MEDIA_LOADER_PEER_VERSION, REQUEST_TIMEOUTS } from '../initializers/constants'
import { sequelizeTypescript } from '../initializers/database'
import { VideoFileModel } from '../models/video/video-file'
import { VideoStreamingPlaylistModel } from '../models/video/video-streaming-playlist'
import { storeHLSFile } from './object-storage'
import { generateHLSMasterPlaylistFilename, generateHlsSha256SegmentsFilename, getHlsResolutionPlaylistFilename } from './paths'
import { VideoPathManager } from './video-path-manager'

async function updateStreamingPlaylistsInfohashesIfNeeded () {
  const playlistsToUpdate = await VideoStreamingPlaylistModel.listByIncorrectPeerVersion()

  // Use separate SQL queries, because we could have many videos to update
  for (const playlist of playlistsToUpdate) {
    await sequelizeTypescript.transaction(async t => {
      const videoFiles = await VideoFileModel.listByStreamingPlaylist(playlist.id, t)

      playlist.assignP2PMediaLoaderInfoHashes(playlist.Video, videoFiles)
      playlist.p2pMediaLoaderPeerVersion = P2P_MEDIA_LOADER_PEER_VERSION

      await playlist.save({ transaction: t })
    })
  }
}

async function updatePlaylistAfterFileChange (video: MVideo, playlist: MStreamingPlaylist) {
  let playlistWithFiles = await updateMasterHLSPlaylist(video, playlist)
  playlistWithFiles = await updateSha256VODSegments(video, playlist)

  // Refresh playlist, operations can take some time
  playlistWithFiles = await VideoStreamingPlaylistModel.loadWithVideoAndFiles(playlist.id)
  playlistWithFiles.assignP2PMediaLoaderInfoHashes(video, playlistWithFiles.VideoFiles)
  await playlistWithFiles.save()

  video.setHLSPlaylist(playlistWithFiles)
}

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

// Avoid concurrency issues when updating streaming playlist files
const playlistFilesQueue = new PQueue({ concurrency: 1 })

function updateMasterHLSPlaylist (video: MVideo, playlistArg: MStreamingPlaylist): Promise<MStreamingPlaylistFilesVideo> {
  return playlistFilesQueue.add(async () => {
    const playlist = await VideoStreamingPlaylistModel.loadWithVideoAndFiles(playlistArg.id)

    const masterPlaylists: string[] = [ '#EXTM3U', '#EXT-X-VERSION:3' ]

    for (const file of playlist.VideoFiles) {
      const playlistFilename = getHlsResolutionPlaylistFilename(file.filename)

      await VideoPathManager.Instance.makeAvailableVideoFile(file.withVideoOrPlaylist(playlist), async videoFilePath => {
        const size = await getVideoStreamDimensionsInfo(videoFilePath)

        const bandwidth = 'BANDWIDTH=' + video.getBandwidthBits(file)
        const resolution = `RESOLUTION=${size?.width || 0}x${size?.height || 0}`

        let line = `#EXT-X-STREAM-INF:${bandwidth},${resolution}`
        if (file.fps) line += ',FRAME-RATE=' + file.fps

        const codecs = await Promise.all([
          getVideoStreamCodec(videoFilePath),
          getAudioStreamCodec(videoFilePath)
        ])

        line += `,CODECS="${codecs.filter(c => !!c).join(',')}"`

        masterPlaylists.push(line)
        masterPlaylists.push(playlistFilename)
      })
    }

    if (playlist.playlistFilename) {
      await video.removeStreamingPlaylistFile(playlist, playlist.playlistFilename)
    }
    playlist.playlistFilename = generateHLSMasterPlaylistFilename(video.isLive)

    const masterPlaylistPath = VideoPathManager.Instance.getFSHLSOutputPath(video, playlist.playlistFilename)
    await writeFile(masterPlaylistPath, masterPlaylists.join('\n') + '\n')

    if (playlist.storage === VideoStorage.OBJECT_STORAGE) {
      playlist.playlistUrl = await storeHLSFile(playlist, playlist.playlistFilename)
      await remove(masterPlaylistPath)
    }

    return playlist.save()
  })
}

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

function updateSha256VODSegments (video: MVideo, playlistArg: MStreamingPlaylist): Promise<MStreamingPlaylistFilesVideo> {
  return playlistFilesQueue.add(async () => {
    const json: { [filename: string]: { [range: string]: string } } = {}

    const playlist = await VideoStreamingPlaylistModel.loadWithVideoAndFiles(playlistArg.id)

    // For all the resolutions available for this video
    for (const file of playlist.VideoFiles) {
      const rangeHashes: { [range: string]: string } = {}
      const fileWithPlaylist = file.withVideoOrPlaylist(playlist)

      await VideoPathManager.Instance.makeAvailableVideoFile(fileWithPlaylist, videoPath => {

        return VideoPathManager.Instance.makeAvailableResolutionPlaylistFile(fileWithPlaylist, async resolutionPlaylistPath => {
          const playlistContent = await readFile(resolutionPlaylistPath)
          const ranges = getRangesFromPlaylist(playlistContent.toString())

          const fd = await open(videoPath, 'r')
          for (const range of ranges) {
            const buf = Buffer.alloc(range.length)
            await read(fd, buf, 0, range.length, range.offset)

            rangeHashes[`${range.offset}-${range.offset + range.length - 1}`] = sha256(buf)
          }
          await close(fd)

          const videoFilename = file.filename
          json[videoFilename] = rangeHashes
        })
      })
    }

    if (playlist.segmentsSha256Filename) {
      await video.removeStreamingPlaylistFile(playlist, playlist.segmentsSha256Filename)
    }
    playlist.segmentsSha256Filename = generateHlsSha256SegmentsFilename(video.isLive)

    const outputPath = VideoPathManager.Instance.getFSHLSOutputPath(video, playlist.segmentsSha256Filename)
    await outputJSON(outputPath, json)

    if (playlist.storage === VideoStorage.OBJECT_STORAGE) {
      playlist.segmentsSha256Url = await storeHLSFile(playlist, playlist.segmentsSha256Filename)
      await remove(outputPath)
    }

    return playlist.save()
  })
}

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

async function buildSha256Segment (segmentPath: string) {
  const buf = await readFile(segmentPath)
  return sha256(buf)
}

function downloadPlaylistSegments (playlistUrl: string, destinationDir: string, timeout: number, bodyKBLimit: number) {
  let timer
  let remainingBodyKBLimit = bodyKBLimit

  logger.info('Importing HLS playlist %s', playlistUrl)

  return new Promise<void>(async (res, rej) => {
    const tmpDirectory = join(CONFIG.STORAGE.TMP_DIR, await generateRandomString(10))

    await ensureDir(tmpDirectory)

    timer = setTimeout(() => {
      deleteTmpDirectory(tmpDirectory)

      return rej(new Error('HLS download timeout.'))
    }, timeout)

    try {
      // Fetch master playlist
      const subPlaylistUrls = await fetchUniqUrls(playlistUrl)

      const subRequests = subPlaylistUrls.map(u => fetchUniqUrls(u))
      const fileUrls = uniq(flatten(await Promise.all(subRequests)))

      logger.debug('Will download %d HLS files.', fileUrls.length, { fileUrls })

      for (const fileUrl of fileUrls) {
        const destPath = join(tmpDirectory, basename(fileUrl))

        await doRequestAndSaveToFile(fileUrl, destPath, { bodyKBLimit: remainingBodyKBLimit, timeout: REQUEST_TIMEOUTS.REDUNDANCY })

        const { size } = await stat(destPath)
        remainingBodyKBLimit -= (size / 1000)

        logger.debug('Downloaded HLS playlist file %s with %d kB remained limit.', fileUrl, Math.floor(remainingBodyKBLimit))
      }

      clearTimeout(timer)

      await move(tmpDirectory, destinationDir, { overwrite: true })

      return res()
    } catch (err) {
      deleteTmpDirectory(tmpDirectory)

      return rej(err)
    }
  })

  function deleteTmpDirectory (directory: string) {
    remove(directory)
      .catch(err => logger.error('Cannot delete path on HLS download error.', { err }))
  }

  async function fetchUniqUrls (playlistUrl: string) {
    const { body } = await doRequest(playlistUrl)

    if (!body) return []

    const urls = body.split('\n')
      .filter(line => line.endsWith('.m3u8') || line.endsWith('.mp4'))
      .map(url => {
        if (url.startsWith('http://') || url.startsWith('https://')) return url

        return `${dirname(playlistUrl)}/${url}`
      })

    return uniq(urls)
  }
}

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

export {
  updateMasterHLSPlaylist,
  updateSha256VODSegments,
  buildSha256Segment,
  downloadPlaylistSegments,
  updateStreamingPlaylistsInfohashesIfNeeded,
  updatePlaylistAfterFileChange
}

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

function getRangesFromPlaylist (playlistContent: string) {
  const ranges: { offset: number, length: number }[] = []
  const lines = playlistContent.split('\n')
  const regex = /^#EXT-X-BYTERANGE:(\d+)@(\d+)$/

  for (const line of lines) {
    const captured = regex.exec(line)

    if (captured) {
      ranges.push({ length: parseInt(captured[1], 10), offset: parseInt(captured[2], 10) })
    }
  }

  return ranges
}