// 资源嗅探脚本：在安装页面播放器脚本之前接管 fetch / XMLHttpRequest / createObjectURL，
// 把真正被下载的媒体地址（mp4 / m3u8 等）回报给宿主程序，用于"下载视频"按钮。
(function () {
  if (window.__mediaSniffInstalled) return;
  window.__mediaSniffInstalled = true;

  window.__mediaUrls = [];
  window.__m3u8Blobs = [];

  var MEDIA_EXT =
    /\.(mp4|flv|m3u8|mpd|mkv|mov|m4v|webm|f4v|3gp|mpg|mpeg|ts)(\?|#|$)/i;
  var PLAIN_EXT =
    /\.(jpg|jpeg|png|gif|webp|ico|svg|bmp|css|js|json|woff2?|ttf|map|txt)(\?|#|$)/i;

  function isMediaUrl(u) {
    if (!u) return false;
    u = String(u);
    if (u.indexOf("blob:") === 0 || u.indexOf("data:") === 0) return false;
    if (PLAIN_EXT.test(u)) return false;
    return MEDIA_EXT.test(u) || /\/(video|vod|playback|media)[\/-]/i.test(u);
  }

  function absUrl(u) {
    try {
      return new URL(String(u), location.href).href;
    } catch (e) {
      return String(u);
    }
  }

  function post(msg) {
    try {
      if (
        window.chrome &&
        window.chrome.webview &&
        window.chrome.webview.postMessage
      ) {
        window.chrome.webview.postMessage(JSON.stringify(msg));
      }
    } catch (e) {}
  }

  function remember(text) {
    if (!text || typeof text !== "string") return;
    if (text.indexOf("#EXTM3U") < 0) return;
    if (window.__m3u8Blobs.indexOf(text) >= 0) return;
    window.__m3u8Blobs.push(text);
    post({ type: "hlsText", text: text });
  }

  function report(u) {
    try {
      var full = absUrl(u);
      if (!isMediaUrl(full)) return;
      if (window.__mediaUrls.indexOf(full) >= 0) return;
      window.__mediaUrls.push(full);
      // base 是发出这个请求的文档地址：播放器常在跨域 iframe 里，
      // 宿主必须用它当 Referer，用顶层页面地址会被防盗链判为非法来源
      post({ type: "media", url: full, base: location.href });
    } catch (e) {}
  }

  window.__reportMedia = report;
  window.__rememberHlsText = remember;

  // 抖音等站点会用 atob(base64) 把播放地址还原出来，这里顺手抓一份解码结果
  try {
    var origAtob = window.atob;
    if (origAtob) {
      window.atob = function (s) {
        var r = origAtob.apply(this, arguments);
        try {
          if (r && typeof r === "string") {
            if (r.indexOf("#EXTM3U") >= 0) remember(r);
            else if (isMediaUrl(r)) report(r);
          }
        } catch (e) {}
        return r;
      };
    }
  } catch (e) {}

  try {
    var origFetch = window.fetch;
    if (origFetch) {
      window.fetch = function (input, init) {
        try {
          var u =
            typeof input === "string" || input instanceof URL
              ? input
              : input && input.url;
          if (u) report(u);
        } catch (e) {}
        return origFetch.apply(this, arguments);
      };
    }
  } catch (e) {}

  try {
    var xhrOpen = XMLHttpRequest.prototype.open;
    var xhrSend = XMLHttpRequest.prototype.send;
    XMLHttpRequest.prototype.open = function (method, u) {
      try {
        if (u) report(u);
      } catch (e) {}
      return xhrOpen.apply(this, arguments);
    };
    XMLHttpRequest.prototype.send = function () {
      var xhr = this;
      try {
        xhr.addEventListener("load", function () {
          try {
            if (xhr.responseType === "" || xhr.responseType === "text") {
              remember(xhr.responseText);
            } else if (
              xhr.responseType === "blob" &&
              xhr.response &&
              xhr.response.text
            ) {
              xhr.response.text().then(remember);
            }
          } catch (e) {}
        });
      } catch (e) {}
      return xhrSend.apply(this, arguments);
    };
  } catch (e) {}

  // MSE 播放时 video.src 只能是 blob:，抓不到 http 地址，所以靠上面的分片嗅探兜底；
  // 这里额外记录 createObjectURL 的调用，方便识别"确实在用 MSE"。
  try {
    var ocu = window.URL && window.URL.createObjectURL;
    if (ocu) {
      window.URL.createObjectURL = function (obj) {
        var u = ocu.apply(this, arguments);
        try {
          window.__usesMse = true;
          if (obj && typeof obj.text === "function") obj.text().then(remember);
        } catch (e) {}
        return u;
      };
    }
  } catch (e) {}
})();