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

/*
 * decaffeinate suggestions:
 * DS102: Remove unnecessary code created because of implicit returns
 * DS207: Consider shorter variations of null checks
 * Full docs: https://github.com/decaffeinate/decaffeinate/blob/main/docs/suggestions.md
 */
const Metadata = {
  init() {
    if (!Conf['WEBM Metadata'] || !['index', 'thread'].includes(g.VIEW)) {
      return
    }

    return Callbacks.Post.push({
      name: 'WEBM Metadata',
      cb: this.node,
    })
  },

  node() {
    for (let i = 0; i < this.files.length; i++) {
      var file = this.files[i]
      if (/webm$/i.test(file.url)) {
        var el

        if (this.isClone) {
          el = $('.webm-title', file.text)
        } else {
          el = $.el('span', { className: 'webm-title' })
          el.dataset.index = i
          $.extend(el, { innerHTML: '<a href="javascript:;"></a>' })
          $.add(file.text, [$.tn(' '), el])
        }
        if (el.children.length === 1) {
          $.one(el.lastElementChild, 'mouseover focus', Metadata.load)
        }
      }
    }
  },

  load() {
    $.rmClass(this.parentNode, 'error')
    $.addClass(this.parentNode, 'loading')
    const { index } = this.parentNode.dataset
    return CrossOrigin.binary(
      Get.postFromNode(this).files[+index].url,
      data => {
        $.rmClass(this.parentNode, 'loading')
        if (data != null) {
          const title = Metadata.parse(data)
          const output = $.el('span', { textContent: title || '' })
          if (title == null) {
            $.addClass(this.parentNode, 'not-found')
          }
          $.before(this, output)
          this.parentNode.tabIndex = 0
          this.parentNode.onfocus = function () {
            this.parentNode.focus()
          }
          return (this.tabIndex = -1)
        } else {
          $.addClass(this.parentNode, 'error')
          return $.one(this, 'click', Metadata.load)
        }
      },
      { Range: 'bytes=0-9999' }
    )
  },

  parse(data) {
    const readInt = function () {
      let n = data[i++]
      let len = 0
      while (n < 0x80 >> len) {
        len++
      }
      n ^= 0x80 >> len
      while (len-- && i < data.length) {
        n = (n << 8) ^ data[i++]
      }
      return n
    }

    var i = 0
    while (i < data.length) {
      var element = readInt()
      var size = readInt()
      if (element === 0x3ba9) {
        // Title
        var title = ''
        while (size-- && i < data.length) {
          title += String.fromCharCode(data[i++])
        }
        return decodeURIComponent(escape(title)) // UTF-8 decoding
      } else if (![0x8538067, 0x549a966].includes(element)) {
        // Segment, Info
        i += size
      }
    }
    return null
  },
}
export default Metadata