import { CONFIG } from '../../initializers/constants'
import { listIndexInstancesHost, getMajorInstanceVersion } from '../requests/instances-index'
import { client } from '../../helpers/meilisearch'
import { logger } from '../../helpers/logger'
import Bluebird from 'bluebird'

async function buildInstanceHosts () {
  let indexHosts = await listIndexInstancesHost()

  if (CONFIG.INSTANCES_INDEX.WHITELIST.ENABLED) {
    const whitelistHosts = Array.isArray(CONFIG.INSTANCES_INDEX.WHITELIST.HOSTS)
      ? CONFIG.INSTANCES_INDEX.WHITELIST.HOSTS
      : []

    indexHosts = indexHosts.filter(h => whitelistHosts.includes(h))
  }

  indexHosts = await Bluebird.filter(indexHosts, async indexHost => {
    const instanceVersion = await getMajorInstanceVersion(indexHost)

    if (instanceVersion < 4) {
      logger.info(`Do not index ${indexHost} because the major version is too low (v${instanceVersion} < v4)`)

      return false
    }

    return true
  }, { concurrency: 10 })

  const dbHosts = await listDBInstances()
  const removedHosts = getRemovedHosts(dbHosts, indexHosts)

  return { indexHosts, removedHosts }
}

export {
  buildInstanceHosts
}

// ##################################################

async function listDBInstances () {
  const setResult = new Set<string>()
  const indexes = [
    CONFIG.MEILISEARCH.INDEXES.VIDEOS,
    CONFIG.MEILISEARCH.INDEXES.CHANNELS
  ]

  for (const index of indexes) {
    const result = await client.index(index).searchForFacetValues({ facetName: 'host' })

    for (const b of result.facetHits) {
      setResult.add(b.value)
    }
  }

  return Array.from(setResult)
}

function getRemovedHosts (dbHosts: string[], indexHosts: string[]) {
  return dbHosts.filter(dbHost => indexHosts.includes(dbHost) === false)
}