// ==UserScript==
// @name           Youtube Subtitle Downloader v36
// @description    Download Subtitles
// @include        https://*youtube.com/*
// @author         Cheng Zheng
// @copyright      2009 Tim Smart; 2011 gw111zz; 2014~2023 Cheng Zheng;
// @license        GNU GPL v3.0 or later. http://www.gnu.org/copyleft/gpl.html
// @require        https://code.jquery.com/jquery-1.12.4.min.js
// @version        36
// @grant          GM_xmlhttpRequest
// @grant         unsafeWindow
// @namespace     https://greasyfork.org/users/5711
// ==/UserScript==

/*
[What is this?]
  This Tampermonkey script allows you to download Youtube "Automatic subtitle" and "closed subtitle".

[Note]
  If it doesn't work (rarely), try to refresh the page.
  If problem still exists after refreshing, send an email to guokrfans@gmail.com.

[Who built this?]
  Author :  Cheng Zheng (郑诚)
  Email  :  guokrfans@gmail.com
  Github :  https://github.com/1c7/Youtube-Auto-Subtitle-Download

[Note for Developers]
  1. Some comments are written in Chinese.
  2. This code handles both "Auto" and "Closed" subtitles.

[Test Video]
  https://www.youtube.com/watch?v=bkVsus8Ehxs
  This videos only has a closed English subtitle, with no auto subtitles.

  https://www.youtube.com/watch?v=-WEqFzyrbbs
  no subtitle at all

  https://www.youtube.com/watch?v=9AzNEG1GB-k
  have a lot of subtitles

  https://www.youtube.com/watch?v=tqGkOvrKGfY
  1:36:33  super long subtitle

[How does it work?]
  The code can be roughly divided into three parts:
    1. Add a button on the page. (UI)
    2. Detect if subtitle exists.
    3. Convert subtitle format, then download.

[Test Enviroment]
  Works best on Chrome + Tampermonkey. 
  There are plenty Chromium-based Browser, I do not guarantee this work on all of them;

备注: 
  有时候不能用，是因为 jQuery 的 CDN 无法载入，解决办法是修改这一行
  // @require https://code.jquery.com/jquery-1.12.4.min.js
  改成一个别的 jQuery 地址，比如
  https://cdn.bootcdn.net/ajax/libs/jquery/1.12.4/jquery.js
  https://cdn.staticfile.org/jquery/1.12.4/jquery.min.js

更新日志

## 2022年12月23号：升级到 v35
  常规升级。把下载框挪到标题下面，之前太靠下了（放到了描述的下面）现在挪上去一点。
*/

;(function () {

  // Config
  var NO_SUBTITLE = 'No Subtitle'
  var HAVE_SUBTITLE = 'Download Subtitles'
  var TEXT_LOADING = 'Loading...'
  const BUTTON_ID =
    'youtube-subtitle-downloader-by-1c7-latest-update-2022-decemeber-23'
  // Config

  var HASH_BUTTON_ID = `#${BUTTON_ID}`

  // initialize
  var first_load = true // indicate if first load this webpage or not
  var youtube_playerResponse_1c7 = null // for auto subtitle
  unsafeWindow.caption_array = [] // store all subtitle

  $(document).ready(function () {
    make_sure_it_load_properly_before_continue()
  })

  async function wait_until_element_exists(element_identifier) {
    var retry_count = 0
    var RETRY_LIMIT = 50
    return new Promise(function (resolve, reject) {
      var intervalID = setInterval(function () {
        try {
          var element = document.querySelector(element_identifier)
          if (element != null) {
            resolve(true)
          } else {
            retry_count = retry_count + 1
            // console.log(`重试次数 ${retry_count}`);
            if (retry_count > RETRY_LIMIT) {
              clearInterval(intervalID)
              reject(false)
            }
          }
        } catch (error) {
          reject(false)
        }
      }, 330)
    })
  }

  async function make_sure_it_load_properly_before_continue() {
    var id = new_Youtube_2022_UI_element_identifier()
    var result = await wait_until_element_exists(id)
    if (result) {
      init_UI()
    }
  }

  // trigger when loading new page
  // (actually this would also trigger when first loading, that's not what we want, that's why we need to use firsr_load === false)
  // (new Material design version would trigger this "yt-navigate-finish" event. old version would not.)
  var body = document.getElementsByTagName('body')[0]
  body.addEventListener('yt-navigate-finish', function (event) {
    // 2021-8-9 测试结果：yt-navigate-finish 可以正常触发
    if (current_page_is_video_page() === false) {
      return
    }
    youtube_playerResponse_1c7 = event.detail.response.playerResponse // for auto subtitle
    unsafeWindow.caption_array = [] // clean up (important, otherwise would have more and more item and cause error)

    // if use click to another page, init again to get correct subtitle
    if (first_load === false) {
      remove_subtitle_download_button()
      init_UI()
    }
  })

  // 我们用这个元素判断是不是 2022 年新 UI 。
  // return Element;
  function new_Youtube_2022_UI_element() {
    return document.querySelector(new_Youtube_2022_UI_element_identifier())
  }

  function new_Youtube_2022_UI_element_identifier() {
    var document_querySelector = '#owner.item.style-scope.ytd-watch-metadata'
    return document_querySelector
  }

  // return true / false
  // Detect [new version UI(material design)] OR [old version UI]
  // I tested this, accurated.
  function new_material_design_version() {
    var old_title_element = document.getElementById('watch7-headline')
    if (old_title_element) {
      return false
    } else {
      return true
    }
  }

  // return true / false
  function current_page_is_video_page() {
    return get_url_video_id() !== null
  }

  // return string like "RW1ChiWyiZQ",  from "https://www.youtube.com/watch?v=RW1ChiWyiZQ"
  // or null
  function get_url_video_id() {
    return getURLParameter('v')
  }

  //https://stackoverflow.com/questions/11582512/how-to-get-url-parameters-with-javascript/11582513#11582513
  function getURLParameter(name) {
    return (
      decodeURIComponent(
        (new RegExp('[?|&]' + name + '=' + '([^&;]+?)(&|#|;|$)').exec(
          location.search
        ) || [null, ''])[1].replace(/\+/g, '%20')
      ) || null
    )
  }

  function remove_subtitle_download_button() {
    $(HASH_BUTTON_ID).remove()
  }

  // 初始化
  function init_UI() {
    var html_element = get_main_UI_element()

    // 旧版 UI
    var old_anchor_element = document.getElementById('watch7-headline')
    if (old_anchor_element != null) {
      old_anchor_element.appendChild(html_element)
    }

    // 新版 UI
    var anchor = document.querySelector('#above-the-fold #title')
    if (anchor) {
      anchor.appendChild(html_element)
    }

    first_load = false
  }

  function get_main_UI_element() {
    var div = document.createElement('div'),
      select = document.createElement('select'),
      option = document.createElement('option')

    var css_div = `display: table; 
    margin-top:4px;
    border: 1px solid rgb(0, 183, 90); 
    cursor: pointer; color: rgb(255, 255, 255); 
    border-top-left-radius: 3px; 
    border-top-right-radius: 3px; 
    border-bottom-right-radius: 3px; 
    border-bottom-left-radius: 3px; 
    background-color: #00B75A;
    `
    div.setAttribute('style', css_div)

    div.id = BUTTON_ID

    select.id = 'captions_selector'
    select.disabled = true
    let css_select = `display:block; 
    border: 1px solid rgb(0, 183, 90); 
    cursor: pointer; 
    color: rgb(255, 255, 255); 
    background-color: #00B75A;
    padding: 4px;
    `
    select.setAttribute('style', css_select)

    option.textContent = TEXT_LOADING
    option.selected = true
    select.appendChild(option)

    // 下拉菜单里，选择一项后触发下载
    select.addEventListener(
      'change',
      function () {
        download_subtitle(this)
      },
      false
    )

    div.appendChild(select) // put <select> into <div>

    // put the div into page: new material design
    var title_element = document.querySelectorAll(
      '.title.style-scope.ytd-video-primary-info-renderer'
    )
    if (title_element) {
      $(title_element[0]).after(div)
    }

    load_language_list(select)

    // <a> element is for download
    var a = document.createElement('a')
    a.style.cssText = 'display:none;'
    a.setAttribute('id', 'ForSubtitleDownload')
    var body = document.getElementsByTagName('body')[0]
    body.appendChild(a)

    return div
  }

  // trigger when user select <option>
  async function download_subtitle(selector) {
    // if user select first <option>, we just return, do nothing.
    if (selector.selectedIndex == 0) {
      return
    }

    var caption = caption_array[selector.selectedIndex - 1]
    // because first <option> is for display, so index - 1

    var result = null
    var filename = null // 保存文件名

    // if user choose auto subtitle
    if (caption.lang_code == 'AUTO') {
      result = await get_auto_subtitle()
      filename = get_file_name(get_auto_subtitle_name())
    } else {
      // closed subtitle
      let lang_code = caption.lang_code
      let lang_name = caption.lang_name
      result = await get_closed_subtitle(lang_code)
      filename = get_file_name(lang_name)
    }

    let srt = parse_youtube_XML_to_SRT(result)
    downloadString(srt, 'text/plain', filename)

    // After download, select first <option>
    selector.options[0].selected = true
  }

  // Return something like: "(English)How Did Python Become A Data Science Powerhouse?.srt"
  function get_file_name(x) {
    // var method_1 = '(' + x + ')' + document.title + '.srt'; // 如果有通知数，文件名也会带上，比较烦，这种方式不好
    // var method_2 = '(' + x + ')' + get_title() + '.srt';
    var method_3 = `(${x})${get_title()}_video_id_${get_video_id()}.srt`
    return method_3
  }

  // 拿完整字幕的 XML
  // async function get_closed_subtitles() {
  //   var list_url = 'https://video.google.com/timedtext?hl=en&v=' + get_url_video_id() + '&type=list';
  //   // Example: https://video.google.com/timedtext?hl=en&v=if36bqHypqk&type=list
  //   return new Promise(function (resolve, reject) {
  //     GM_xmlhttpRequest({
  //       method: 'GET',
  //       url: list_url,
  //       onload: function (xhr) {
  //         resolve(xhr.responseText)
  //       }
  //     })
  //   })
  // }

  // detect if "auto subtitle" and "closed subtitle" exist
  // and add <option> into <select>
  async function load_language_list(select) {
    // auto
    var auto_subtitle_exist = false

    // closed
    var closed_subtitle_exist = false

    // get auto subtitle
    var auto_subtitle_url = get_auto_subtitle_xml_url()
    if (auto_subtitle_url != false) {
      auto_subtitle_exist = true
    }

    var captionTracks = get_captionTracks()
    if (
      captionTracks != undefined &&
      typeof captionTracks === 'object' &&
      captionTracks.length > 0
    ) {
      closed_subtitle_exist = true
    }

    // if no subtitle at all, just say no and stop
    if (auto_subtitle_exist == false && closed_subtitle_exist == false) {
      select.options[0].textContent = NO_SUBTITLE
      disable_download_button()
      return false
    }

    // if at least one type of subtitle exist
    select.options[0].textContent = HAVE_SUBTITLE
    select.disabled = false

    var option = null // for <option>
    var caption_info = null // for our custom object

    // if auto subtitle exist
    if (auto_subtitle_exist) {
      caption_info = {
        lang_code: 'AUTO', // later we use this to know if it's auto subtitle
        lang_name: get_auto_subtitle_name(), // for display only
      }
      caption_array.push(caption_info)

      option = document.createElement('option')
      option.textContent = caption_info.lang_name
      select.appendChild(option)
    }

    // if closed_subtitle_exist
    if (closed_subtitle_exist) {
      for (var i = 0, il = captionTracks.length; i < il; i++) {
        var caption = captionTracks[i]
        if (caption.kind == 'asr') {
          continue
        }
        let lang_code = caption.languageCode
        let lang_translated = caption.name.simpleText
        let lang_name = lang_code_to_local_name(lang_code, lang_translated)
        caption_info = {
          lang_code: lang_code,
          lang_name: lang_name,
        }
        caption_array.push(caption_info)
        // 加到 caption_array 里, 一个全局变量, 待会要靠它来下载
        option = document.createElement('option')
        option.textContent = caption_info.lang_name
        select.appendChild(option)
      }
    }
  }

  function disable_download_button() {
    $(HASH_BUTTON_ID)
      .css('border', '#95a5a6')
      .css('cursor', 'not-allowed')
      .css('background-color', '#95a5a6')
    $('#captions_selector')
      .css('border', '#95a5a6')
      .css('cursor', 'not-allowed')
      .css('background-color', '#95a5a6')

    if (new_material_design_version()) {
      $(HASH_BUTTON_ID).css('padding', '6px')
    } else {
      $(HASH_BUTTON_ID).css('padding', '5px')
    }
  }

  // 处理时间. 比如 start="671.33"  start="37.64"  start="12" start="23.029"
  // 处理成 srt 时间, 比如 00:00:00,090    00:00:08,460    00:10:29,350
  function process_time(s) {
    s = s.toFixed(3)
    // 超棒的函数, 不论是整数还是小数都给弄成3位小数形式
    // 举个柚子:
    // 671.33 -> 671.330
    // 671 -> 671.000
    // 注意函数会四舍五入. 具体读文档

    var array = s.split('.')
    // 把开始时间根据句号分割
    // 671.330 会分割成数组: [671, 330]

    var Hour = 0
    var Minute = 0
    var Second = array[0] // 671
    var MilliSecond = array[1] // 330
    // 先声明下变量, 待会把这几个拼好就行了

    // 我们来处理秒数.  把"分钟"和"小时"除出来
    if (Second >= 60) {
      Minute = Math.floor(Second / 60)
      Second = Second - Minute * 60
      // 把 秒 拆成 分钟和秒, 比如121秒, 拆成2分钟1秒

      Hour = Math.floor(Minute / 60)
      Minute = Minute - Hour * 60
      // 把 分钟 拆成 小时和分钟, 比如700分钟, 拆成11小时40分钟
    }
    // 分钟，如果位数不够两位就变成两位，下面两个if语句的作用也是一样。
    if (Minute < 10) {
      Minute = '0' + Minute
    }
    // 小时
    if (Hour < 10) {
      Hour = '0' + Hour
    }
    // 秒
    if (Second < 10) {
      Second = '0' + Second
    }
    return Hour + ':' + Minute + ':' + Second + ',' + MilliSecond
  }

  // copy from: https://gist.github.com/danallison/3ec9d5314788b337b682
  // Thanks! https://github.com/danallison
  // work in Chrome 66
  // test passed: 2018-5-19
  function downloadString(text, fileType, fileName) {
    var blob = new Blob([text], {
      type: fileType,
    })
    var a = document.createElement('a')
    a.download = fileName
    a.href = URL.createObjectURL(blob)
    a.dataset.downloadurl = [fileType, a.download, a.href].join(':')
    a.style.display = 'none'
    document.body.appendChild(a)
    a.click()
    document.body.removeChild(a)
    setTimeout(function () {
      URL.revokeObjectURL(a.href)
    }, 1500)
  }

  // https://css-tricks.com/snippets/javascript/unescape-html-in-js/
  // turn HTML entity back to text, example: &quot; should be "
  function htmlDecode(input) {
    var e = document.createElement('div')
    e.class =
      'dummy-element-for-tampermonkey-Youtube-Subtitle-Downloader-script-to-decode-html-entity'
    e.innerHTML = input
    return e.childNodes.length === 0 ? '' : e.childNodes[0].nodeValue
  }

  // return URL or null;
  // later we can send a AJAX and get XML subtitle
  function get_auto_subtitle_xml_url() {
    try {
      var captionTracks = get_captionTracks()
      for (var index in captionTracks) {
        var caption = captionTracks[index]
        if (caption.kind === 'asr') {
          return captionTracks[index].baseUrl
        }
        // ASR – A caption track generated using automatic speech recognition.
        // https://developers.google.com/youtube/v3/docs/captions
      }
      return false
    } catch (error) {
      return false
    }
  }

  async function get_auto_subtitle() {
    var url = get_auto_subtitle_xml_url()
    if (url == false) {
      return false
    }
    var result = await get(url)
    return result
  }

  async function get_closed_subtitle(lang_code) {
    try {
      var captionTracks = get_captionTracks()
      for (var i in captionTracks) {
        var caption = captionTracks[i]
        if (caption.languageCode === lang_code && caption.kind != 'asr') {
          // 必须写 caption.kind != 'asr'
          // 否则会下载2个字幕文件（也就是这个分支会进来2次）
          // 因为 lang_code 是 "en" 会 match 2条纪录，一条是自动字幕，一条是完整字幕
          // "自动字幕"那条是 kind=asr
          // "完整字幕"那条没有 kind 属性
          let url = captionTracks[i].baseUrl
          let result = await get(url)
          return result
        }
      }
      return false
    } catch (error) {
      return false
    }
  }

  // Youtube return XML. we want SRT
  // input: Youtube XML format
  // output: SRT format
  function parse_youtube_XML_to_SRT(youtube_xml_string) {
    if (youtube_xml_string === '') {
      return false
    }
    var text = youtube_xml_string.getElementsByTagName('text')
    var result = ''
    var BOM = '\uFEFF'
    result = BOM + result // store final SRT result
    var len = text.length
    for (var i = 0; i < len; i++) {
      var index = i + 1
      var content = text[i].textContent.toString()
      content = content.replace(/(<([^>]+)>)/gi, '') // remove all html tag.
      var start = text[i].getAttribute('start')
      var end =
        parseFloat(text[i].getAttribute('start')) +
        parseFloat(text[i].getAttribute('dur'))

      // 保留这段代码
      // 如果希望字幕的结束时间和下一行的开始时间相同（连在一起）
      // 可以取消下面的注释
      // if (i + 1 >= len) {
      //   end = parseFloat(text[i].getAttribute('start')) + parseFloat(text[i].getAttribute('dur'));
      // } else {
      //   end = text[i + 1].getAttribute('start');
      // }

      // we want SRT format:
      /*
          1
          00:00:01,939 --> 00:00:04,350
          everybody Craig Adams here I'm a

          2
          00:00:04,350 --> 00:00:06,720
          filmmaker on YouTube who's digging
      */
      var new_line = '\n'
      result = result + index + new_line
      // 1

      var start_time = process_time(parseFloat(start))
      var end_time = process_time(parseFloat(end))
      result = result + start_time
      result = result + ' --> '
      result = result + end_time + new_line
      // 00:00:01,939 --> 00:00:04,350

      content = htmlDecode(content)
      // turn HTML entity back to text. example: &#39; back to apostrophe (')

      result = result + content + new_line + new_line
      // everybody Craig Adams here I'm a
    }
    return result
  }

  // return "English (auto-generated)" or a default name;
  function get_auto_subtitle_name() {
    try {
      var captionTracks = get_captionTracks()
      for (var index in captionTracks) {
        var caption = captionTracks[index]
        if (typeof caption.kind === 'string' && caption.kind == 'asr') {
          return captionTracks[index].name.simpleText
        }
      }
      return 'Auto Subtitle'
    } catch (error) {
      return 'Auto Subtitle'
    }
  }

  function get_youtube_data() {
    return document.getElementsByTagName('ytd-app')[0].data.playerResponse
  }

  function get_captionTracks() {
    let data = get_youtube_data()
    var captionTracks =
      data?.captions?.playerCaptionsTracklistRenderer?.captionTracks
    return captionTracks
  }

  // Input a language code, output that language name in current locale
  // 如果当前语言是中文简体, Input: "de" Output: 德语
  // if current locale is English(US), Input: "de" Output: "Germany"
  function lang_code_to_local_name(languageCode, fallback_name) {
    try {
      var captionTracks = get_captionTracks()
      for (var i in captionTracks) {
        var caption = captionTracks[i]
        if (caption.languageCode === languageCode) {
          let simpleText = captionTracks[i].name.simpleText
          if (simpleText) {
            return simpleText
          } else {
            return fallback_name
          }
        }
      }
    } catch (error) {
      return fallback_name
    }
  }

  // 获取视频标题
  function get_title() {
    // 方法1：先尝试拿到标题
    var title_element = document.querySelector(
      'h1.title.style-scope.ytd-video-primary-info-renderer'
    )
    if (title_element != null) {
      var title = title_element.innerText
      // 能拿到就返回
      if (title != undefined && title != null && title != '') {
        return title
      }
    }
    // 方法2：如果方法1失效用这个
    return ytplayer.bootstrapPlayerResponse.videoDetails.videoId // 这个会 delay, 如果页面跳转了，这个获得的标题还是旧的
  }

  function get_video_id() {
    return ytplayer.bootstrapPlayerResponse.videoDetails.videoId
  }

  // Usage: var result = await get(url)
  function get(url) {
    return $.ajax({
      url: url,
      type: 'get',
      success: function (r) {
        return r
      },
      fail: function (error) {
        return error
      },
    })
  }

  const wait = (ms) => new Promise((resolve) => setTimeout(resolve, ms))

  // 等待一个元素存在
  // https://stackoverflow.com/questions/5525071/how-to-wait-until-an-element-exists
  function waitForElm(selector) {
    return new Promise((resolve) => {
      if (document.querySelector(selector)) {
        return resolve(document.querySelector(selector))
      }

      const observer = new MutationObserver((mutations) => {
        if (document.querySelector(selector)) {
          resolve(document.querySelector(selector))
          observer.disconnect()
        }
      })

      observer.observe(document.body, {
        childList: true,
        subtree: true,
      })
    })
  }

})()