import { config } from './config.js'
import { getRedisKey, hash } from './util.js'
import { logger } from './logger.js'
import * as cache from './cache.js'
import * as redis from './redis.js'

let latestVersion

export const fetchLatestVersion = async () => {
  const infos = await Promise.all(config.urls.map(async baseUrl => {
    try {
      const response = await fetch(new URL('meta.json', baseUrl))
      if (!response.ok) throw new Error()
      const meta = await response.json()
      const version = meta.commitSha || meta.buildDate || meta.version
      if (!version) throw new Error()
      return version
    } catch (err) {
      logger.warn(`[Version] UI container at ${baseUrl} does not have meta.json. Fall back to version hash based on manifest.`)
    }
    try {
      const response = await fetch(new URL('manifest.json', baseUrl))
      if (!response.ok) throw new Error()
      const manifest = await response.json()
      return hash(manifest)
    } catch (err) {
      logger.error(`[Version] Cannot fetch manifest from ${baseUrl}. Version info will not be correct.`)
    }
  }))
  return hash(infos)
}

export async function getLatestVersion () {
  if (latestVersion) return latestVersion
  if (redis.isEnabled()) {
    const version = await redis.client.get(getRedisKey({ name: 'latestVersion' }))
    if (version) {
      logger.info(`[Version] Got initial version from redis: '${version}'`)
      return (latestVersion = version)
    }
  }

  const version = await fetchLatestVersion()
  logger.info(`[Version] Fetched initial version: '${version}'`)

  if (redis.isEnabled()) {
    redis.pubClient.publish(getRedisKey({ name: 'updateLatestVersion' }), version)
    await redis.client.set(getRedisKey({ name: 'latestVersion' }), version)
  }

  return (latestVersion = version)
}

export function registerLatestVersionListener (client) {
  if (!redis.isEnabled()) return

  const key = getRedisKey({ name: 'updateLatestVersion' })
  client.subscribe(key, (errs, count) => logger.info(`[Redis] Subscribed to ${key}.`))
  client.on('message', async (channel, version) => {
    if (channel !== key) return
    logger.info(`[Version] Received 'updateLatestVersion' event. Clearing cache. New version: '${version}'`)
    await config.load()
    cache.clear()
    latestVersion = version
  })
}

export async function updateVersionProcessor () {
  logger.info('[Version] Check for new version')
  await config.load()
  const [storedVersion, fetchedVersion] = await Promise.all([
    getLatestVersion(),
    fetchLatestVersion()
  ])
  if (storedVersion === fetchedVersion) {
    logger.info(`[Version] No new version has been found. No update needed. Current version: ${storedVersion}`)
    return fetchedVersion
  }
  logger.info(`[Version] Found new source version. Current version: '${storedVersion}', new version: '${fetchedVersion}'`)
  if (redis.isEnabled()) {
    redis.pubClient.publish(getRedisKey({ name: 'updateLatestVersion' }), fetchedVersion)
    await redis.client.set(getRedisKey({ name: 'latestVersion' }), fetchedVersion)
  } else {
    // if redis is disabled, this will only be trigger by a setInterval and not from a redis event
    logger.info('[Version] Clear local cache due to version update.')
    cache.clear()
  }
  return (latestVersion = fetchedVersion)
}