import { config } from './config.js'
import { getRedisKey, isJSFile } from './util.js'
import { getCSSDependenciesFor, getViteManifests } from './manifests.js'
import * as cache from './cache.js'
import { logger } from './logger.js'
import { NotFoundError } from './errors.js'
import * as redis from './redis.js'
import zlib from 'node:zlib'
import { promisify } from 'node:util'
const gzip = promisify(zlib.gzip)

const compressFileSize = Number(process.env.COMPRESS_FILE_SIZE)
const compressionMimeTypes = (process.env.COMPRESS_FILE_TYPES || '').split(' ')
const compressionWhitelistRegex = new RegExp(`^(${compressionMimeTypes.join('|')})$`)

export function createWritable (body) {
  if (typeof body !== 'string' && !(body instanceof Buffer)) return JSON.stringify(body)
  return body
}

async function createFileBuffer (response, dependencies) {
  const cssString = dependencies && dependencies.map(file => `"${file}"`).join(',')
  const appendix = cssString && `\n/*injected by ui-middleware*/document.dispatchEvent(new CustomEvent("load-css",{detail:{css:[${cssString}]}}))`
  const resBuffer = await response.arrayBuffer()
  const appendixLength = appendix?.length || 0
  const buffer = Buffer.alloc(resBuffer.byteLength + appendixLength)

  buffer.fill(Buffer.from(resBuffer), 0, resBuffer.byteLength)
  if (appendix) buffer.write(appendix, resBuffer.byteLength)

  return buffer
}

export async function fetchFileWithHeadersFromBaseUrl (path, baseUrl, version) {
  const [response, dependencies] = await Promise.all([
    fetch(new URL(path, baseUrl)),
    isJSFile(path) && getCSSDependenciesFor({ file: path.substr(1), version })
  ])

  if (!response.ok) throw new NotFoundError(`Error fetching file: ${path}`)

  const result = {
    body: await createFileBuffer(response, dependencies),
    headers: {
      'content-type': response.headers.get('content-type'),
      dependencies
    }
  }

  if (result.body.length > compressFileSize && compressionWhitelistRegex.test(result.headers['content-type'])) {
    result.body = await gzip(result.body)
    result.headers['content-encoding'] = 'gzip'
  }

  return result
}

export async function fetchFileWithHeaders ({ path, version }) {
  const viteManifests = await getViteManifests({ version })
  const module = viteManifests[path.substr(1)]
  if (module?.meta?.baseUrl) {
    try {
      return fetchFileWithHeadersFromBaseUrl(path, module.meta.baseUrl, version)
    } catch (err) {
      logger.debug(`[Files] File ${path} had a baseUrl but could not be found on that server: ${err}`)
    }
  }

  return Promise.any(config.urls.map(baseUrl => fetchFileWithHeadersFromBaseUrl(path, baseUrl, version)))
}

export function getFile ({ version, path }) {
  const key = getRedisKey({ version, name: `${path}` })

  // try to get the file synchronously.
  const data = cache.getCache()[key]
  if (data) {
    logger.debug(`[Files] Resolve from memory: ${key}`)
    return data
  }

  // if synchronously does not work, store the async promise for further requests
  const promise = (async () => {
    const bodyKey = getRedisKey({ version, name: `${path}:body` })
    const metaKey = getRedisKey({ version, name: `${path}:meta` })

    if (redis.isEnabled()) {
      const [body, meta = '{}'] = await Promise.all([
        redis.client.getBuffer(bodyKey),
        redis.client.get(metaKey)
      ])

      if (body) {
        logger.debug(`[Files] Resolve from redis: ${key}`)
        return (cache.getCache()[key] = { body, ...JSON.parse(meta) })
      }
    }

    const dataFromServer = await fetchFileWithHeaders({ version, path })
    if (redis.isEnabled()) {
      logger.debug(`[Files] Store in redis: ${key}`)
      const { body, ...rest } = dataFromServer
      redis.client.set(bodyKey, createWritable(body))
      redis.client.set(metaKey, JSON.stringify(rest))
    }

    // overwrite cache with synchronous data
    logger.debug(`[Files] Store in memory: ${key}`)
    return (cache.getCache()[key] = dataFromServer)
  })()

  // temporary set to promise
  cache.getCache()[key] = promise
  return promise
}