import {exec} from 'child_process'
import path from 'path'
import fs from 'fs-extra'

function filewalker (dir, done) {
  let results = []

  fs.readdir(dir, function (err, list) {
    if (err) return done(err)

    let pending = list.length

    if (!pending) return done(null, results)

    list.forEach(function (file) {
      file = path.resolve(dir, file)

      fs.stat(file, function (err, stat) {
        if (err) return done(err)

        // If directory, execute a recursive call
        if (stat && stat.isDirectory()) {
          filewalker(file, function (err, res) {
            if (err) return done(err)
            results = results.concat(res)
            if (!--pending) done(null, results)
          })
        } else {
          results.push(file)

          if (!--pending) done(null, results)
        }
      })
    })
  })
}

async function insertDB (db, track) {
  let ensure = await db.get('SELECT * FROM Track WHERE title=? AND artist=?', track.title, track.artist)
  if (ensure) {
    return null
  }

  await db.run('INSERT INTO Track VALUES (NULL,?,?,?,?,?,?,?,?)',
    [track.title, track.artist, track.file, track.album || null, track.genre || null, track.track || null,
      track.year || null, Math.floor(track.duration)])

  return track
}

function getFiles (dir) {
  return new Promise((resolve, reject) => {
    filewalker(dir, (err, files) => {
      if (err) return reject(err)
      resolve(files)
    })
  })
}

function promiseExec (cmd, opts) {
  return new Promise((resolve, reject) => {
    exec(cmd, opts, function (err, stdout, stderr) {
      if (err) return reject(err)
      resolve({stdout, stderr})
    })
  })
}

function askAsync (rl, q) {
  return new Promise((resolve, reject) => {
    rl.question(q, resolve)
  })
}

function copyAsync (fsrc, fdst) {
  return new Promise((resolve, reject) => {
    let source = fs.createReadStream(path.resolve(fsrc))
    let dest = fs.createWriteStream(path.resolve(fdst))

    source.pipe(dest)
    source.on('end', resolve)
    source.on('error', reject)
  })
}

export default {getFiles, promiseExec, askAsync, insertDB, copyAsync}