import Callbacks from '../classes/Callbacks'
import Header from '../General/Header'
import { Conf, d,g } from '../globals/globals'
import $ from '../platform/$'

/*
 * decaffeinate suggestions:
 * DS101: Remove unnecessary use of Array.from
 * DS102: Remove unnecessary code created because of implicit returns
 * Full docs: https://github.com/decaffeinate/decaffeinate/blob/main/docs/suggestions.md
 */
const ImageLoader = {
  init() {
    if (!['index', 'thread', 'archive'].includes(g.VIEW)) {
      return
    }
    const replace =
      Conf['Replace JPG'] ||
      Conf['Replace PNG'] ||
      Conf['Replace GIF'] ||
      Conf['Replace WEBM']
    if (!Conf['Image Prefetching'] && !replace) {
      return
    }

    Callbacks.Post.push({
      name: 'Image Replace',
      cb: this.node,
    })

    $.on(d, 'PostsInserted', function () {
      if (ImageLoader.prefetchEnabled || replace) {
        return g.posts.forEach(ImageLoader.prefetchAll)
      }
    })

    if (Conf['Replace WEBM']) {
      $.on(
        d,
        'scroll visibilitychange 4chanXInitFinished PostsInserted',
        this.playVideos
      )
    }

    if (!Conf['Image Prefetching'] || !['index', 'thread'].includes(g.VIEW)) {
      return
    }

    const el = $.el('a', {
      href: 'javascript:;',
      title: 'Prefetch Images',
      className: 'fa fa-bolt disabled',
      textContent: 'Prefetch',
    })

    $.on(el, 'click', this.toggle)

    return Header.addShortcut('prefetch', el, 525)
  },

  node() {
    if (this.isClone) {
      return
    }
    for (var file of this.files) {
      if (Conf['Replace WEBM'] && file.isVideo) {
        ImageLoader.replaceVideo(this, file)
      }
      ImageLoader.prefetch(this, file)
    }
  },

  replaceVideo(post, file) {
    const { thumb } = file
    const video = $.el('video', {
      preload: 'none',
      loop: true,
      muted: true,
      poster: thumb.src || thumb.dataset.src,
      textContent: thumb.alt,
      className: thumb.className,
    })
    video.setAttribute('muted', 'muted')
    video.dataset.md5 = thumb.dataset.md5
    for (var attr of ['height', 'width', 'maxHeight', 'maxWidth']) {
      video.style[attr] = thumb.style[attr]
    }
    video.src = file.url
    $.replace(thumb, video)
    file.thumb = video
    return (file.videoThumb = true)
  },

  prefetch(post, file) {
    let clone, type
    const { isImage, isVideo, thumb, url } = file
    if (
      file.isPrefetched ||
      !(isImage || isVideo) ||
      post.isHidden ||
      post.thread.isHidden
    ) {
      return
    }
    if (isVideo) {
      type = 'WEBM'
    } else {
      type = url.match(/\.([^.]+)$/)?.[1].toUpperCase()
      if (type === 'JPEG') {
        type = 'JPG'
      }
    }
    const replace =
      Conf[`Replace ${type}`] && !/spoiler/.test(thumb.src || thumb.dataset.src)
    if (!replace && !ImageLoader.prefetchEnabled) {
      return
    }
    if ($.hasClass(d, 'catalog-mode')) {
      return
    }
    if (
      ![post, ...Array.from(post.clones)].some(clone =>
        d.contains(clone.nodes.root)
      )
    ) {
      return
    }
    file.isPrefetched = true
    if (file.videoThumb) {
      for (clone of post.clones) {
        clone.file.thumb.preload = 'auto'
      }
      thumb.preload = 'auto'
      // XXX Cloned video elements with poster in Firefox cause momentary display of image loading icon.
      if ($.engine === 'gecko') {
        $.on(thumb, 'loadeddata', function () {
          return this.removeAttribute('poster')
        })
      }
      return
    }

    const el = $.el(isImage ? 'img' : 'video')
    if (isVideo) {
      el.preload = 'auto'
    }
    if (replace && isImage) {
      $.on(el, 'load', function () {
        for (clone of post.clones) {
          clone.file.thumb.src = url
        }
        return (thumb.src = url)
      })
    }
    return (el.src = url)
  },

  prefetchAll(post) {
    for (var file of post.files) {
      ImageLoader.prefetch(post, file)
    }
  },

  toggle() {
    ImageLoader.prefetchEnabled = !ImageLoader.prefetchEnabled
    this.classList.toggle('disabled', !ImageLoader.prefetchEnabled)
    if (ImageLoader.prefetchEnabled) {
      g.posts.forEach(ImageLoader.prefetchAll)
    }
  },

  playVideos() {
    // Special case: Quote previews are off screen when inserted into document, but quickly moved on screen.
    const qpClone = $.id('qp')?.firstElementChild
    return g.posts.forEach(function (post) {
      for (post of [post, ...Array.from(post.clones)]) {
        for (var file of post.files) {
          if (file.isVideo && !file.isPrefetched) {
            const { thumb } = file
            if (qpClone === thumb) {
              continue
            }
            if (thumb.getBoundingClientRect().top < window.innerHeight) {
              ImageLoader.prefetch(post, file)
            }
          }
        }
      }
    })
  },
}
export default ImageLoader