import cacheFile from 'express-cache-file'
import express from 'express'

let app = express()

app.use(
  cacheFile('public', {
    cacheSize: '50mb',
    update: {
      expire: '5 seconds',
      mode: 'cache_first',
    },
  }),
)

app.listen(8100, () => {
  console.log('listening on http://localhost:8100')
})

export function cacheFile(
  root: string,
  options?: CacheFileOptions,
): (req, res, next) => void

export default cacheFile

export type CacheFileOptions = {
  readMode?: ReadMode
  update?: false | UpdateOptions
  cacheSize?: CacheSize
  redirect?: boolean // redirect '/' to 'index.html', default true
}

export type UpdateOptions = {
  expire?: UpdateInterval
  mode?: UpdateMode
}

export type UpdateMode =
  | 'cache_first' // default
  | 'wait'

export type ReadMode =
  | undefined
  | 'async' // default
  | 'sync'

export type UpdateInterval =
  | undefined
  | false // equivalent to to 'never'
  | 'never' // default
  | 'immediate'
  | number // ms, zero is equivalent to 'immediate'
  | string // duration format, e.g. '5 minutes'

export type CacheSize =
  | undefined
  | 'unlimited' // default
  | number // bytes
  | string // size format, e.g. '5mb'