const fs = require("fs")
const path = require("path")

const promisify = fn => {
  return function () {
    let args = arguments;
    return new Promise(function (resolve, reject) {
      [].push.call(args, function (err, result) {
        if (err) {
          console.log(err)
          reject(err);
        } else {
          resolve(result);
        }
      });
      fn.apply(null, args);
    });
  }
}

const readdir = promisify(fs.readdir)
const stat = promisify(fs.stat)
const findFile = (dir = '.', cb) => {
  return readdir(dir).then(apps => {
    return Promise.all(apps.map(e => {
      let cPath = path.join(dir, e)
      return stat(cPath).then(state => {
        if (state.isDirectory()) {
          return findFile(cPath, cb)
        } else if (state.isFile()) {
          cb && cb(cPath)
        }
      })
    }))
  })
}
module.exports = {readdir, stat, findFile}