const cache = require('co-cache')(defaultConfig);
cache(fn[, options]) => AsyncFunction

process.env.DEBUG = 'co-cache'

const cache = require('.')({
  prefix: 'cache:',
  expire: 10 * 60 * 1000 // default expire
})

;(async function () {
  const someAsyncFn = cache(async function someAsyncFn (number) {
    console.log(`someAsyncFn: ${number}`)
    return number
  }, {
    key: function (number) {
      if (number >= 4) {
        return false // only cache when number < 4
      }
      return this.name + ':' + number
    }
  })

  await someAsyncFn(1)
  await someAsyncFn(2)
  await someAsyncFn(2) // get from cache

  await someAsyncFn.get(3)
  await someAsyncFn.set(3, 'some value') // manually set cache
  await someAsyncFn.get(3) // get from cache

  await someAsyncFn(4) // not cache

  await someAsyncFn.clear(1) // clear cache
  await someAsyncFn.clear(2) // clear cache
  await someAsyncFn.clear(3) // clear cache
  await someAsyncFn.clear(4) // no effect, because there is no cache
})().catch(console.error)

function defaultGet (redis, cacheKey) {
  return redis
    .get(cacheKey)
    .then((result) => {
      if (result != null) {
        return JSON.parse(result)
      }
    })
    .catch(() => {})
}

function defaultSet (redis, cacheKey, result, ms) {
  // cannot save `undefined`` value, `null` is ok
  if (result === undefined) {
    return
  }
  return redis
    .set(cacheKey, JSON.stringify(result), 'PX', ms)
    .catch(() => {})
}