const fs = require('fs')
const path = require('path')
const Jimp = require('jimp')
const imagemin = require('imagemin')
const rimraf = require('rimraf')
const zopfli = require('node-zopfli')
const brotli = require('iltorb')
const filewalker = require('filewalker')
const chalk = require('chalk')
const log = console.log;

// clear dist path
const clear_dist = config => new Promise((resolve, reject) => rimraf(path.join(config.basepath, config.dist_path, config.image_path), err => err ? reject(err) : resolve()))

// webp conversion
const convertToWebp = config => {
  return new Promise((resolve, reject) => {
    let cbw_counter = 0
    const webp_plug = [require('imagemin-webp')({method: 6})]
    const wcb = () => cbw_counter++ === config.images.length - 1 ? resolve() : false
    config.images.forEach(orig => {
      let folder = path.basename(path.dirname(orig))
      let destination = path.join(config.basepath, config.dist_path, config.image_path, folder)
      let original_path = path.join(destination, path.basename(orig)).replace(',svg', '') 
      imagemin([original_path], destination, {plugins: webp_plug}).then(wcb)
    })
  }) 
}

// losslessly optimize images
const lossless_optimize = config => {
  return new Promise((resolve, reject) => {
    let cb_counter = 0
    const plugins = [
      require('imagemin-jpegtran')(),
      require('imagemin-jpegoptim')(),
      require('imagemin-mozjpeg')(),
      require('imagemin-zopfli')({more: true}),  
      require('imagemin-pngcrush')(),
      require('imagemin-advpng')(),
      require('imagemin-optipng')(),
      require('imagemin-svgo')(),
    ]
    const cb = () => cb_counter++ === config.images.length - 1 ? resolve() : false

    config.images.forEach(orig => {
      const folder = path.basename(path.dirname(orig))
      const destination = path.join(config.basepath, config.dist_path, config.image_path, folder)
      const source = path.join(config.basepath, config.image_path, orig)
      imagemin([source], destination, {plugins: plugins}).then(cb)
    })
  })
}

// compress svg with zopfli & brotli
const compress_svg = config => {
  return new Promise((resolve, reject) => {
    const find_images = () => {
      let images = []
      filewalker(path.join(config.basepath, config.dist_path, config.image_path))
        .on('file', file => images.push(path.join(config.basepath, config.dist_path, config.image_path, file)))
        .on('done', filter_svgs.bind(null, images))
        .walk()
    }
    
    const filter_svgs = images => compress_items(images.filter(image => image.substr(-4) === '.svg'))

    const compress_items = images => {
      const iterations = images.length * 2
      let scb_counter = 0
      const scb = () => scb_counter++ === iterations ? resolve() : false
      images.forEach(image => {
        // read original file contents
        fs.readFile(image, 'utf-8', (err, contents) => {
          // write zopfli compressed file
          zopfli.gzip(Buffer.from(contents), (err, output) => fs.writeFile(image + '.gz', output, err => err ? reject(err) : scb()))
          // write brotli compressed file
          brotli.compress(Buffer.from(contents), (err, output) => fs.writeFile(image + '.br', output, err => err ? reject(err) : scb()))
        })
      })
    }

    find_images()
  })
}

module.exports = (config, result) => {
  return new Promise(async (resolve, reject) => {
    try {
      log('    ', chalk.green('>>'), 'Deleting old destination folder')
      const cleared = await clear_dist(config)
      log('    ', chalk.green('>>'), 'Optimize images')
      const optimized = await lossless_optimize(config)
      log('    ', chalk.green('>>'), 'Convert to WebP')
      const webp = await convertToWebp(config)
      log('    ', chalk.green('>>'), 'Static compress SVG')
      const compressedSvg = compress_svg(config)
      resolve({cleared, optimized, webp, compressedSvg})
    } catch (err) {
      reject(err)
    }
  })
}

/*
Jimp.read('../img/content/article.jpg', (err, image) => {
    if (err) throw err
    image.resize(Jimp.AUTO, 400).quality(100).write('../dist/article-home.jpg')
})
*/