// ==UserScript==
// @name         B站视频优先加载 · 先视频后其他
// @name:zh-CN   B站视频优先加载 · 先视频后其他
// @namespace    https://github.com/example/bilibili-fast-video
// @version      2.0.0
// @description  打开B站视频页时先把带宽和连接让给视频流：评论/推荐/直播/弹幕等非必要请求暂缓发起（不屏蔽），待视频开始播放或缓冲充分后自动开始加载，兼顾视频流畅与页面完整。可用 localStorage 配置。
// @description:zh-CN 打开B站视频页时先把带宽和连接让给视频流：评论/推荐/直播/弹幕等非必要请求暂缓发起（不屏蔽），待视频开始播放或缓冲充分后自动开始加载，兼顾视频流畅与页面完整。可用 localStorage 配置。
// @author       you
// @license      MIT
// @match        https://www.bilibili.com/video/*
// @match        https://www.bilibili.com/bangumi/play/*
// @match        https://www.bilibili.com/list/*
// @match        https://m.bilibili.com/video/*
// @run-at       document-start
// @grant        none
// @noframes
// ==/UserScript==

(function () {
  'use strict';

  /* ============ 配置（localStorage，键名 biliFastCfg） ============ */
  var LS_KEY = 'biliFastCfg';
  var DEFAULTS = {
    enabled: true,             // 总开关
    deferNonEssential: true,   // 视频优先：延迟加载评论/推荐流/直播/空间等
    deferDanmaku: true,        // 弹幕列表同样延迟（视频开播后再加载）
    deferTimeout: 10000,       // 兜底：最多延迟多久后开始加载其他（毫秒）
    releaseOnInteraction: true,// 用户滚动/点击时立即开始加载其他
    priority: true,            // 视频 CDN preconnect 预热 + 请求高优先级
    showButton: true           // 右下角悬浮开关按钮
  };

  function readCfg() {
    var cfg = {};
    for (var k in DEFAULTS) cfg[k] = DEFAULTS[k];
    try {
      var raw = localStorage.getItem(LS_KEY);
      if (raw) {
        var saved = JSON.parse(raw);
        for (var k2 in saved) if (k2 in DEFAULTS) cfg[k2] = saved[k2];
      }
    } catch (e) {}
    return cfg;
  }

  var cfg = readCfg();
  if (!cfg.enabled) return;

  var released = false;          // 是否已开始加载"其他"内容
  var pendingFetches = [];       // 被暂缓的 fetch 调用（释放时按序发出）
  var pendingXhrs = [];          // 被暂缓的 XHR 调用

  /* ============ 判定：该请求是否应暂缓（而不是屏蔽） ============ */
  function shouldDefer(raw) {
    if (released || !raw) return false;
    var url;
    try { url = new URL(String(raw), location.href); } catch (e) { return false; }
    var host = url.hostname;
    var path = url.pathname;

    // 视频流 CDN：永不延迟（这些是视频本身）
    if (/bilivideo\.(com|cn)$/.test(host) || /acgvideo\.com$/.test(host)) return false;

    // 直播
    if (/\blive\.bilibili\.com$/.test(host) || /^api\.live\.bilibili\.com$/.test(host)) return true;

    // 弹幕列表（弹幕 WebSocket 不拦截，保持实时性）
    if (cfg.deferDanmaku && /^api\.bilibili\.com$/.test(host) && /\/x\/v[12]\/dm\//.test(path)) return true;

    // api.bilibili.com：白名单（播放/交互必需）之外的业务接口全部暂缓
    if (/^api\.bilibili\.com$/.test(host)) {
      // 关闭弹幕延迟时，弹幕接口即使不在白名单也放行
      if (!cfg.deferDanmaku && /\/x\/v[12]\/dm\//.test(path)) return false;
      var allow = [
        /\/x\/web-interface\/(wbi\/)?view/,  // 视频信息
        /\/x\/web-interface\/(wbi\/)?nav/,   // 登录状态
        /\/x\/player\//,                     // 播放器配置/播放地址(playurl)/分P列表
        /\/x\/report\//,                     // 播放心跳、进度上报（保存观看历史）
        /\/x\/web-interface\/archive\/stat/, // 播放/弹幕/点赞计数
        /\/x\/web-interface\/like\//,        // 点赞/三连
        /\/x\/web-interface\/coin\//,        // 投币
        /\/x\/web-interface\/favorite\//,    // 收藏
        /\/x\/v2\/fav\//,                    // 稍后再看
        /\/x\/web-interface\/archive\/add/,  // 稍后再看
        /\/x\/relation\//                    // 关注/粉丝
      ];
      for (var i = 0; i < allow.length; i++) {
        if (allow[i].test(path)) return false;
      }
      // 评论、相关推荐、底部推荐流、在线人数、作者空间、排行等 → 暂缓
      return true;
    }

    return false;
  }

  /* ============ 释放：开始正常加载被暂缓的请求 ============ */
  var origSend;
  function release() {
    if (released) return;
    released = true;
    // 取消"隐藏待加载区域"的样式类，评论区/右侧栏等恢复可见
    try { document.documentElement.classList.remove('bili-defer'); } catch (e) {}
    // 按序发出被暂缓的 fetch
    var fs = pendingFetches.splice(0);
    for (var i = 0; i < fs.length; i++) {
      try { fs[i](); } catch (e) {}
    }
    // 按序发出被暂缓的 XHR（若页面已 abort 则跳过）
    var xs = pendingXhrs.splice(0);
    for (var j = 0; j < xs.length; j++) {
      try {
        if (typeof origSend === 'function' && xs[j].xhr.readyState === 1) {
          origSend.apply(xs[j].xhr, xs[j].args);
        }
      } catch (e) {}
    }
  }

  /* ============ fetch 暂缓 ============ */
  var origFetch = window.fetch;
  if (typeof origFetch === 'function') {
    window.fetch = function (input, init) {
      var url = (typeof input === 'string' ? input : (input && input.url)) || '';
      if (cfg.deferNonEssential && shouldDefer(url)) {
        var self = this;
        return new Promise(function (resolve, reject) {
          pendingFetches.push(function () {
            try {
              var p = origFetch.call(self, input, init);
              p.then(resolve, reject);
            } catch (e) {
              reject(e);
            }
          });
        });
      }
      // 视频 CDN 请求提高网络优先级（不支持 priority 选项的浏览器自动忽略）
      if (cfg.priority && init && init.priority == null && /bilivideo\.(com|cn)|acgvideo\.com/.test(url)) {
        try { init = Object.assign({}, init, { priority: 'high' }); } catch (e) {}
      }
      var p = origFetch.call(this, input, init);
      if (p && typeof p.then === 'function') {
        p.then(function (r) { sniffPlayurlHosts(url, r); }, function () {});
      }
      return p;
    };
  }

  /* ============ XHR 暂缓 ============ */
  var XHR = window.XMLHttpRequest;
  if (XHR && XHR.prototype) {
    var origOpen = XHR.prototype.open;
    origSend = XHR.prototype.send;
    XHR.prototype.open = function (method, url) {
      try { this.__biliDefer = cfg.deferNonEssential && shouldDefer(url); } catch (e) { this.__biliDefer = false; }
      return origOpen.apply(this, arguments);
    };
    XHR.prototype.send = function () {
      if (this.__biliDefer) {
        this.__biliDefer = false;
        pendingXhrs.push({ xhr: this, args: arguments });
        return; // 暂不发出，等释放
      }
      return origSend.apply(this, arguments);
    };
  }

  /* ============ CDN preconnect 预热 ============ */
  var preconnected = {};
  function preconnect(host) {
    if (!host || preconnected[host]) return;
    preconnected[host] = 1;
    var head = document.head || document.documentElement;
    try {
      var pc = document.createElement('link');
      pc.rel = 'preconnect';
      pc.href = 'https://' + host;
      pc.crossOrigin = 'anonymous';
      head.appendChild(pc);
      var dn = document.createElement('link');
      dn.rel = 'dns-prefetch';
      dn.href = 'https://' + host;
      head.appendChild(dn);
    } catch (e) {}
  }

  // 解析 playurl 响应，提前为真实视频 CDN 主机建立连接
  function sniffPlayurlHosts(url, resp) {
    if (!cfg.priority || !resp || !resp.clone) return;
    try {
      resp.clone().text().then(function (t) {
        var m = t.match(/https?:\/\/[^"'\\\s]+/g) || [];
        for (var i = 0; i < m.length; i++) {
          try {
            var h = new URL(m[i]).hostname;
            if (/bilivideo\.(com|cn)$/.test(h) || /acgvideo\.com$/.test(h)) preconnect(h);
          } catch (e) {}
        }
      }).catch(function () {});
    } catch (e) {}
  }

  /* ============ 视频元素优先级 ============ */
  var boosted = (typeof WeakSet !== 'undefined') ? new WeakSet() : null;
  function boostVideo(v) {
    if (!v || (boosted && boosted.has(v))) return;
    try {
      if ('fetchPriority' in v) v.fetchPriority = 'high';
      else v.setAttribute('fetchpriority', 'high');
      if ('preload' in v) v.preload = 'auto';
      if ('decoding' in v) v.decoding = 'async';
      if (boosted) boosted.add(v);
    } catch (e) {}
  }

  /* ============ 释放触发：视频开播/缓冲充分/用户交互/兜底超时 ============ */
  function onProgress() {
    try {
      var v = this;
      var b = v.buffered;
      if (b && b.length && v.duration) {
        var end = b.end(b.length - 1);
        // 已缓冲足够时长（60s 或时长一半）→ 视频无忧，开始加载其他
        if (end >= Math.min(60, v.duration) || end >= v.duration * 0.5) release();
      }
    } catch (e) {}
  }

  var watched = (typeof WeakSet !== 'undefined') ? new WeakSet() : null;
  function watchVideo(v) {
    if (!v) return;
    boostVideo(v);
    if (!cfg.deferNonEssential || (watched && watched.has(v))) return;
    try {
      watched.add(v);
      v.addEventListener('playing', release);   // 开始播放 → 加载其他
      v.addEventListener('canplay', release);   // 缓冲到可播放 → 加载其他
      v.addEventListener('error', release);     // 视频出错 → 不耽误其他内容
      v.addEventListener('progress', onProgress);
    } catch (e) {}
  }

  /* ============ 暂缓期间隐藏待加载区域（释放后自动恢复） ============ */
  function injectDeferCss() {
    try {
      var st = document.createElement('style');
      st.id = 'bili-fast-defer-css';
      st.textContent =
        'html.bili-defer .right-container,' +
        'html.bili-defer #comment,' +
        'html.bili-defer .comment-container,' +
        'html.bili-defer .bili-comment,' +
        'html.bili-defer .bili-footer,' +
        'html.bili-defer #reco-wrap,' +
        'html.bili-defer #reco_list,' +
        'html.bili-defer #live_room,' +
        'html.bili-defer .live-room { visibility:hidden !important; }';
      (document.head || document.documentElement).appendChild(st);
      document.documentElement.classList.add('bili-defer');
    } catch (e) {}
  }

  /* ============ 悬浮开关按钮 ============ */
  function addToggle() {
    var btn = document.createElement('div');
    btn.id = 'bili-fast-toggle';
    btn.textContent = '⚡';
    btn.title = 'B站视频优先加载：当前' + (cfg.deferNonEssential ? '开启' : '关闭') + '，点击切换并刷新页面';
    btn.setAttribute('style',
      'position:fixed;right:14px;bottom:90px;z-index:2147483647;width:34px;height:34px;line-height:32px;' +
      'text-align:center;font-size:16px;border-radius:50%;cursor:pointer;user-select:none;' +
      'background:' + (cfg.deferNonEssential ? 'rgba(0,161,214,.92)' : 'rgba(120,120,120,.92)') + ';' +
      'color:#fff;box-shadow:0 2px 8px rgba(0,0,0,.25);font-family:system-ui,sans-serif;');
    btn.addEventListener('click', function () {
      cfg.deferNonEssential = !cfg.deferNonEssential;
      try { localStorage.setItem(LS_KEY, JSON.stringify(cfg)); } catch (e) {}
      location.reload();
    });
    try { document.documentElement.appendChild(btn); } catch (e) {}
  }

  /* ============ 启动 ============ */
  try {
    if (cfg.deferNonEssential) {
      injectDeferCss();
      // 兜底超时：无论视频是否播放，最多延迟 deferTimeout 后开始加载其他
      setTimeout(release, cfg.deferTimeout);
      // 用户滚动/点击（说明在浏览页面而非等视频）→ 立即开始加载其他
      if (cfg.releaseOnInteraction) {
        ['scroll', 'wheel', 'click', 'keydown', 'touchstart'].forEach(function (t) {
          try {
            window.addEventListener(t, release, { capture: true, passive: true });
          } catch (e) {
            try { window.addEventListener(t, release, true); } catch (e2) {}
          }
        });
      }
    }
    if (cfg.priority) {
      preconnect('upos-sz-mirrorcos.bilivideo.com');
      preconnect('upos-sz-mirror08.bilivideo.com');
      preconnect('mcdn.bilivideo.cn');
    }
    if (cfg.showButton) addToggle();

    // 监听视频元素出现（SPA 切换视频也适用）
    if (window.MutationObserver) {
      var obs = new MutationObserver(function () {
        try { watchVideo(document.querySelector('video')); } catch (e) {}
      });
      obs.observe(document.documentElement, { childList: true, subtree: true });
    }
    watchVideo(document.querySelector('video'));

    window.__BILI_FAST__ = { cfg: cfg, LS_KEY: LS_KEY, shouldDefer: shouldDefer, release: release }; // 调试入口
  } catch (e) {}
})();