background.js

// -----------------------------------------------------------------------------

// https://developer.chrome.com/docs/extensions/reference/runtime/#property-lastError
// https://developer.chrome.com/docs/extensions/reference/pageAction/#method-show
// https://developer.chrome.com/docs/extensions/reference/pageAction/#method-hide
const pageAction_noop_callback = () => {
  if (chrome.runtime.lastError)
    console.log(chrome.runtime.lastError.message)
}

const enable_popup = (tab_id) => {
  chrome.pageAction.show(tab_id, pageAction_noop_callback)
}

const disable_popup = (tab_id) => {
  chrome.pageAction.hide(tab_id, pageAction_noop_callback)
}

// -----------------------------------------------------------------------------

const user_agent_regex_pattern = /^.*Chrome\/(\d+)\..*$/i

const get_chrome_major_version = () => {
  const user_agent_string = navigator.userAgent

  return (user_agent_string && user_agent_regex_pattern.test(user_agent_string))
    ? parseInt( user_agent_string.replace(user_agent_regex_pattern, '$1'), 10)
    : 0
}

// -----------------------------------------------------------------------------

const no_video_urls = []
const tab_videos    = {}  // tab_id => {tab_url, videos: [{video_url, referer_url}]}

// return: [{video_url, referer_url}]
const get_videos = (tab_id) => {
  const tab_data = tab_videos[tab_id]

  return (!tab_data || !tab_data.videos || !tab_data.videos.length)
    ? no_video_urls
    : tab_data.videos
}

const delete_tab_data = (tab_id, hide_popup) => {
  delete tab_videos[tab_id]

  if (hide_popup)
    disable_popup(tab_id)
}

const clear_videos = (tab_id, hide_popup) => {
  const tab_data = tab_videos[tab_id]

  if (tab_data && Array.isArray(tab_data.videos))
    tab_data.videos = []

  if (hide_popup)
    disable_popup(tab_id)
}

const video_url_regex_pattern = /\.(?:mp4|mp4v|mpv|m1v|m4v|mpg|mpg2|mpeg|xvid|webm|3gp|avi|mov|mkv|ogv|ogm|m3u8|mpd|ism(?:[vc]|\/manifest)?)(?:[\?#].*)?$/i

// https://developer.chrome.com/docs/extensions/reference/runtime/#event-onInstalled
chrome.runtime.onInstalled.addListener(
  function(details){
    if (details.reason === "install"){
      // initialize default option value(s)
      const chrome_version = get_chrome_major_version()

      const data = {
        urls:     [
          'https://warren-bank.github.io/crx-webcast-reloaded/external_website/index.html',
          'http://webcast-reloaded.surge.sh/index.html',
          'http://gitcdn.link/cdn/warren-bank/crx-webcast-reloaded/gh-pages/external_website/index.html'
        ],
        contexts: {
          "https_text_link":  1,
          "https_chromecast": 1,
          "https_airplay":    2,
          "https_proxy":      2,

          "http_text_link":   (chrome_version >= 72) ? 1 : 2,  // Chrome 72+: Cannot cast to Chromecast from an insecure URL. For a video served over HTTP: If sent to HTTPS page, can cast but cannot watch. If sent to HTTP page, cannot cast (72+) but can watch. By default, prioritizing ability to cast over ability to watch in Chrome browser.
          "http_chromecast":  (chrome_version >= 72) ? 1 : 2,  // Chrome 72+: Cannot cast to Chromecast from an insecure URL. For a video served over HTTP: If sent to HTTPS page, can cast but cannot watch. If sent to HTTP page, cannot cast (72+) but can watch. By default, prioritizing ability to cast over ability to watch in Chrome browser.
          "http_airplay":     2,
          "http_proxy":       2
        }
      }

      const user_options_json = JSON.stringify(data)

      chrome.storage.sync.set({user_options_json})
    }
  }
)

// https://developer.chrome.com/docs/extensions/reference/webRequest/#type-HttpHeaders
const get_referer_value = (headers) => {
  let referer = ''

  if (!headers || !Array.isArray(headers) || !headers.length)
    return referer

  const header = headers.find(header => header.name.toLowerCase() === 'referer')
  if (header)
    referer = header.value

  return referer
}

const get_matching_video_data = (tab_data, video_url) => {
  return tab_data.videos.find(video_data => video_data.video_url === video_url)
}

// https://developer.chrome.com/docs/extensions/reference/webRequest/#registering-event-listeners
// https://developer.chrome.com/docs/extensions/reference/webRequest/#type-ResourceType
// https://developer.chrome.com/docs/extensions/reference/webRequest/#event-onSendHeaders
// https://developer.chrome.com/docs/extensions/reference/webRequest/#type-OnSendHeadersOptions
chrome.webRequest.onSendHeaders.addListener(
  function(details){
    const tab_id = details.tabId
    let tab_data, video_data

    if (details.tabId !== chrome.tabs.TAB_ID_NONE) {
      tab_data = tab_videos[tab_id]

      // should not occur; tab_data is initialized when the tab_url changes
      if (!tab_data) {
        tab_data = {tab_url: "", videos: []}
        tab_videos[tab_id] = tab_data
      }

      const video_url   = details.url.trim()
      const referer_url = get_referer_value(details.requestHeaders) || tab_data.tab_url

      // not a video url?
      if (!video_url_regex_pattern.test(video_url))
        return

      // is a duplicate?
      video_data = get_matching_video_data(tab_data, video_url)
      if (video_data) {
        if (!video_data.referer_url && referer_url) {
          video_data.referer_url = referer_url

          tab_data.videos = [...tab_data.videos]
        }

        return
      }

      video_data = {video_url, referer_url}
      tab_data.videos = [...tab_data.videos, video_data]

      enable_popup(tab_id)
    }
  },
  {
    urls:["<all_urls>"],
    types: ["main_frame", "sub_frame", "object", "xmlhttprequest", "media"]
  },
  (get_chrome_major_version() >= 72)
    ? ['requestHeaders', 'extraHeaders']
    : ['requestHeaders']
)

const tab_url_regex_pattern = /^(?:https?|file):/i

// https://developer.chrome.com/docs/extensions/reference/tabs/#event-onUpdated
chrome.tabs.onUpdated.addListener(
  function(tab_id, change_info, tab){
    const tab_url   =  change_info.url
    const is_reload = (change_info.status === 'loading') && !tab_url

    // reloading the same url in the same tab?
    if (is_reload)
      clear_videos(tab_id, true)

    // not a change to the tab_url?
    if (!tab_url)
      return

    // not a supported url scheme?
    if (!tab_url_regex_pattern.test(tab_url))
      return

    let tab_data = tab_videos[tab_id]

    if (!tab_data || (tab_data.tab_url !== tab_url)) {
      tab_data = {tab_url, videos: []}
      tab_videos[tab_id] = tab_data

      disable_popup(tab_id)
    }
  }
)

// https://developer.chrome.com/docs/extensions/reference/tabs/#event-onRemoved
chrome.tabs.onRemoved.addListener(
  function(tab_id){
    delete_tab_data(tab_id, false)
  }
)

// -----------------------------------------------------------------------------

// exports
window.get_videos   = get_videos
window.clear_videos = clear_videos