import { AsyncQueue, queue } from 'async'
import * as Bluebird from 'bluebird'
import { inspect } from 'util'
import { logger } from '../../helpers/logger'
import { INDEXER_CONCURRENCY, INDEXER_COUNT, INDEXER_QUEUE_CONCURRENCY, SCHEDULER_INTERVALS_MS } from '../../initializers/constants'
import { IndexableVideo } from '../../types/video.model'
import { indexChannels, refreshChannelsIndex, removeChannelsFromHosts, removeNotExistingChannels } from '../elastic-search-channels'
import { buildInstanceHosts } from '../elastic-search-instances'
import { indexVideos, refreshVideosIndex, removeNotExistingVideos, removeVideosFromHosts } from '../elastic-search-videos'
import { getChannel, getVideo, getVideos } from '../peertube-instance'
import { AbstractScheduler } from './abstract-scheduler'

type GetVideoQueueParam = { host: string, uuid: string }
type GetChannelQueueParam = { host: string, name: string }

export class VideosIndexer extends AbstractScheduler {

  private static instance: VideosIndexer

  protected schedulerIntervalMs = SCHEDULER_INTERVALS_MS.videosIndexer

  private indexedHosts: string[] = []

  private readonly indexVideoQueue: AsyncQueue<GetVideoQueueParam>
  private readonly indexChannelQueue: AsyncQueue<GetChannelQueueParam>

  private constructor () {
    super()

    this.indexVideoQueue = queue<GetVideoQueueParam, Error>((task, cb) => {
      this.indexSpecificVideo(task.host, task.uuid)
        .then(() => cb())
        .catch(err => {
          logger.error({ err: inspect(err) }, 'Error in index specific video %s of %s.', task.uuid, task.host)
          cb()
        })
    }, INDEXER_QUEUE_CONCURRENCY)

    this.indexChannelQueue = queue<GetChannelQueueParam, Error>((task, cb) => {
      this.indexSpecificChannel(task.host, task.name)
          .then(() => cb())
          .catch(err => {
            logger.error({ err: inspect(err) }, 'Error in index specific channel %s@%s.', task.name, task.host)
            cb()
          })
    }, INDEXER_QUEUE_CONCURRENCY)

    this.indexChannelQueue.drain(async () => {
      logger.info('Refresh channels index.')
      await refreshChannelsIndex()
    })
  }

  scheduleVideoIndexation (host: string, uuid: string) {
    this.indexVideoQueue.push({ uuid, host })
  }

  scheduleChannelIndexation (host: string, name: string) {
    this.indexChannelQueue.push({ name, host })
  }

  getIndexedHosts () {
    return this.indexedHosts
  }

  protected async internalExecute () {
    return this.runVideosIndexer()
  }

  private async runVideosIndexer () {
    logger.info('Running videos indexer.')

    const { indexHosts, removedHosts } = await buildInstanceHosts()
    this.indexedHosts = indexHosts

    await removeVideosFromHosts(removedHosts)
    await removeChannelsFromHosts(removedHosts)

    await Bluebird.map(indexHosts, async host => {
      try {
        await this.indexHost(host)
      } catch (err) {
        console.error(inspect(err, { depth: 10 }))
        logger.warn({ err: inspect(err) }, 'Cannot index videos from %s.', host)
      }
    }, { concurrency: INDEXER_CONCURRENCY })

    await refreshChannelsIndex()
    await refreshVideosIndex()

    logger.info('Videos indexer ended.')
  }

  private async indexHost (host: string) {
    const channelsToSync = new Set<string>()
    const channelsId = new Set<number>()
    const videosId = new Set<number>()

    let videos: IndexableVideo[] = []
    let start = 0

    logger.info('Adding video data from %s.', host)

    do {
      logger.debug('Getting results from %s (from = %d).', host, start)

      videos = await getVideos(host, start)
      start += videos.length

      logger.debug('Got %d results from %s (from = %d).', videos.length, host, start)

      if (videos.length !== 0) {
        const { created } = await indexVideos(videos)

        logger.debug('Indexed %d videos from %s.', videos.length, host)

        // Fetch complete video foreach created video (to get tags)
        for (const c of created) {
          this.scheduleVideoIndexation(host, c.uuid)
        }
      }

      for (const video of videos) {
        channelsToSync.add(video.channel.name)
        channelsId.add(video.channel.id)
        videosId.add(video.id)
      }
    } while (videos.length === INDEXER_COUNT.VIDEOS && start < 500000)

    logger.info('Added video data from %s.', host)

    for (const c of channelsToSync) {
      this.scheduleChannelIndexation(host, c)
    }

    await removeNotExistingChannels(host, channelsId)
    await removeNotExistingVideos(host, videosId)
  }

  private async indexSpecificVideo (host: string, uuid: string) {
    const video = await getVideo(host, uuid)

    logger.info('Indexing specific video %s of %s.', uuid, host)

    await indexVideos([ video ], true)
  }

  private async indexSpecificChannel (host: string, name: string) {
    const channel = await getChannel(host, name)

    logger.info('Indexing specific channel %s@%s.', name, host)

    await indexChannels([ channel ], true)
  }

  static get Instance () {
    return this.instance || (this.instance = new this())
  }
}