// ==UserScript==
// @name         企学宝 · 防切屏暂停 + 自动起播 + 自动下一节
// @namespace    local.qixuebao
// @version      1.1.0
// @description  课程播放页保持播放、自动起播、播完自动点「下一节」
// @match        https://*.lmschina.net/static/admin/*
// @run-at       document-start
// @grant        none
// ==/UserScript==

(function () {
  'use strict';

  /* ================== 配置 ================== */
  var CFG = {
    keepPlaying: true,
    autoNext:    true,
    autoPlay:    true,
    nextDelay:   2500,
    debug:       true
  };

  var log = CFG.debug
    ? function () { console.log.apply(console, ['[qxb]'].concat([].slice.call(arguments))); }
    : function () {};

  function onPlayPage() {
    return location.hash.indexOf('#/course/play/') === 0;
  }
  function inFrame() {
    try { return window.top !== window; } catch (e) { return true; }
  }
  function guardOn() { return onPlayPage() || inFrame(); }

  /* ========== 1. 防切屏暂停 ========== */
  if (CFG.keepPlaying) {
    var hiddenDesc = Object.getOwnPropertyDescriptor(Document.prototype, 'hidden');
    var visDesc = Object.getOwnPropertyDescriptor(Document.prototype, 'visibilityState');
    var nativeHasFocus = Document.prototype.hasFocus;

    var fakeHasFocus = function () {
      return onPlayPage() ? true : nativeHasFocus.call(document);
    };
    try {
      Document.prototype.hasFocus = fakeHasFocus;
      document.hasFocus = fakeHasFocus;
    } catch (e) { log('hasFocus 伪装失败', e); }

    try {
      Object.defineProperty(document, 'hidden', {
        configurable: true,
        get: function () { return onPlayPage() ? false : hiddenDesc.get.call(document); }
      });
      Object.defineProperty(document, 'visibilityState', {
        configurable: true,
        get: function () { return onPlayPage() ? 'visible' : visDesc.get.call(document); }
      });
    } catch (e) { log('visibility 伪装失败', e); }

    var swallow = function (e) { if (onPlayPage()) e.stopImmediatePropagation(); };
    document.addEventListener('visibilitychange', swallow, true);
    document.addEventListener('webkitvisibilitychange', swallow, true);
    window.addEventListener('blur', swallow, true);

    log('keepPlaying 已启用');
  }

  /* ========== 2. 播完自动下一节 ========== */
  if (CFG.autoNext) {
    var scheduled = false;

    function overlayOpen() {
      var boxes = document.querySelectorAll('.el-message-box__wrapper, .el-dialog__wrapper');
      for (var i = 0; i < boxes.length; i++) {
        if (boxes[i].offsetParent !== null) return true;
      }
      return false;
    }

    function nextButton() {
      var end = document.querySelector('.end-page');
      if (!end || !end.querySelector('p')) return null;
      var btns = end.querySelectorAll('button.el-button--primary');
      for (var i = 0; i < btns.length; i++) {
        if (!btns[i].closest('a') && !btns[i].disabled) return btns[i];
      }
      return null;
    }

    function tick() {
      if (!onPlayPage()) { scheduled = false; return; }
      if (!document.querySelector('.end-page')) { scheduled = false; return; }
      if (scheduled) return;
      scheduled = true;
      setTimeout(function () {
        scheduled = false;
        if (overlayOpen()) { log('有弹窗，暂不切下一节'); return; }
        var b = nextButton();
        if (b) { log('点击「下一节」'); b.click(); }
      }, CFG.nextDelay);
    }

    setInterval(tick, 800);
    log('autoNext 已启用');
  }

  /* ========== 3. 自动起播 ========== */
  if (CFG.autoPlay) {
    var lastTry = new WeakMap();

    function tryPlay(v) {
      var wasMuted = v.muted;
      if (!wasMuted) v.muted = true;
      var p;
      try { p = v.play(); } catch (e) { log('play() 抛错', e); return; }
      if (!p || !p.then) return;
      p.then(function () {
        log('自动起播成功');
        if (!wasMuted) {
          setTimeout(function () {
            v.muted = false;
            if (v.paused) v.play().catch(function () { v.muted = true; v.play().catch(function () {}); });
          }, 300);
        }
      }).catch(function (e) { log('自动起播被拒绝:', e && e.name); });
    }

    setInterval(function () {
      if (!guardOn()) return;
      var vids = document.querySelectorAll('video');
      for (var i = 0; i < vids.length; i++) {
        var v = vids[i];
        if (!v.paused || v.ended) continue;
        if (v.played && v.played.length > 0) continue;
        if (v.readyState < 2) continue;
        var now = Date.now();
        if (now - (lastTry.get(v) || 0) < 3000) continue;
        lastTry.set(v, now);
        tryPlay(v);
      }
    }, 1200);

    log('autoPlay 已启用');
  }
})();