// ==UserScript==
// @name         我周五要吃德克士
// @namespace    scu-ecourse-study-helper
// @version      0.1.0
// @description  识别大川学堂视频、倍速、当前章节，并在正常播放结束后提示进入下一节（不伪造学习进度）
// @match        https://ecourse.scu.edu.cn/learn/course/detail/mooc/courseWare/*
// @grant        none
// @run-at       document-idle
// ==/UserScript==

(() => {
  'use strict';

  const CFG = {
    playbackRate: Number(localStorage.getItem('scu_helper_rate') || 1.5),
    tryAutoplay: true,
    muteForAutoplay: false,
    debug: true
  };

  const log = (...args) => CFG.debug && console.log('[SCU Helper]', ...args);

  let boundVideo = null;
  let endHandler = null;
  let routeKey = '';
  let panel = null;

  function getActiveVideo() {
    // 你提供的页面中，真正课程播放器为 #h5player 下的 video。
    const primary = document.querySelector('#h5player video');
    if (primary && Number.isFinite(primary.duration) && primary.duration > 0) return primary;

    // 兜底：排除页面中空的 controls video。
    return [...document.querySelectorAll('video')]
      .find(v => (v.currentSrc || v.src) && Number.isFinite(v.duration) && v.duration > 0) || null;
  }

  function getSectionItems() {
    return [...document.querySelectorAll('a.section_item')]
      .filter(el => el.querySelector('.course_name'));
  }

  function getCurrentSectionItem() {
    const currentNode = document.querySelector('.el-tree-node.is-current');
    return currentNode?.querySelector('a.section_item') || null;
  }

  function getSectionName(item) {
    return item?.querySelector('.course_name')?.textContent?.trim() || '';
  }

  function getCurrentSectionIndex() {
    const items = getSectionItems();
    const current = getCurrentSectionItem();
    if (!current) return -1;
    return items.indexOf(current);
  }

  function getNextSectionItem() {
    const items = getSectionItems();
    const index = getCurrentSectionIndex();

    if (index >= 0 && index + 1 < items.length) {
      return items[index + 1];
    }

    // 如果 Element UI 在切换时短暂丢失 is-current，则按顶部课程名匹配。
    const title = document.querySelector('.course_title .course_name')?.textContent?.trim();
    if (title) {
      const matched = items.findIndex(x => getSectionName(x) === title);
      if (matched >= 0 && matched + 1 < items.length) return items[matched + 1];
    }

    return null;
  }

  function clickSection(item) {
    if (!item) return false;

    const name = getSectionName(item);
    log('准备进入章节:', name);

    // 使用站点本身 Vue/Element UI 已绑定的 click handler。
    item.scrollIntoView({ behavior: 'smooth', block: 'center' });
    setTimeout(() => item.click(), 250);
    return true;
  }

  // 🔥 修改点1：改为 showConfirm 参数，默认为 false（自动跳转）
  function goNextSection(showConfirm = false) {
    const next = getNextSectionItem();

    if (!next) {
      alert('当前 DOM 中没有找到下一节。可能已到最后一节，或后续章节尚未展开。');
      return;
    }

    const name = getSectionName(next);
    
    // 只有 showConfirm 为 true 时才弹出确认框
    if (showConfirm) {
      if (!confirm(`当前视频已播放结束。\n\n进入下一节：\n${name}？`)) {
        return;
      }
    }
    
    log('自动进入下一节:', name);
    clickSection(next);
  }

  function applyRate(video) {
    if (!video) return;
    const rate = Math.max(0.5, Math.min(2, CFG.playbackRate));
    video.playbackRate = rate;
    video.defaultPlaybackRate = rate;
    log('倍速:', rate);
    updatePanel();
  }

  async function tryPlay(video) {
    if (!video || !CFG.tryAutoplay) return;

    try {
      if (CFG.muteForAutoplay) video.muted = true;
      applyRate(video);
      await video.play();
      log('自动播放成功');
    } catch (err) {
      log('浏览器阻止自动播放，需要点击一次页面后再播放:', err?.message || err);
      updatePanel('浏览器阻止自动播放，点击"播放"即可');
    }
  }

  function bindVideo(video) {
    if (!video || video === boundVideo) return;

    if (boundVideo && endHandler) {
      boundVideo.removeEventListener('ended', endHandler);
    }

    boundVideo = video;
    applyRate(video);

    // 🔥 修改点2：视频结束自动跳转，不弹出确认框
    endHandler = () => {
      log('视频 ended:', getSectionName(getCurrentSectionItem()));
      updatePanel('视频已结束，自动进入下一节...');
      setTimeout(() => goNextSection(), 500); // 不传参，默认为 false
    };

    video.addEventListener('ended', endHandler);

    video.addEventListener('loadedmetadata', () => {
      applyRate(video);
      updatePanel();
    });

    video.addEventListener('ratechange', () => updatePanel());
    video.addEventListener('play', () => updatePanel());
    video.addEventListener('pause', () => updatePanel());
    video.addEventListener('timeupdate', throttle(updatePanel, 1000));

    log('绑定课程视频:', {
      src: video.currentSrc || video.src,
      duration: video.duration
    });

    tryPlay(video);
    updatePanel();
  }

  function throttle(fn, wait) {
    let last = 0;
    return (...args) => {
      const now = Date.now();
      if (now - last >= wait) {
        last = now;
        fn(...args);
      }
    };
  }

  function fmt(sec) {
    if (!Number.isFinite(sec)) return '--:--';
    const m = Math.floor(sec / 60);
    const s = Math.floor(sec % 60);
    return `${String(m).padStart(2,'0')}:${String(s).padStart(2,'0')}`;
  }

  function createPanel() {
    if (document.getElementById('scu-helper-panel')) return;

    panel = document.createElement('div');
    panel.id = 'scu-helper-panel';
    panel.innerHTML = `
      <div class="scu-title">大川学堂学习辅助</div>
      <div id="scu-status">等待识别课程视频…</div>
      <div class="scu-row">
        <button id="scu-play">播放/暂停</button>
        <select id="scu-rate">
          <option value="1">1×</option>
          <option value="1.25">1.25×</option>
          <option value="1.5">1.5×</option>
          <option value="1.75">1.75×</option>
          <option value="2">2×</option>
        </select>
        <button id="scu-next">下一节</button>
      </div>
    `;

    const style = document.createElement('style');
    style.textContent = `
      #scu-helper-panel{
        position:fixed;right:18px;bottom:18px;z-index:2147483647;
        width:290px;padding:12px 14px;border-radius:10px;
        background:rgba(25,25,25,.92);color:#fff;
        font:13px/1.45 -apple-system,BlinkMacSystemFont,"Segoe UI","Microsoft YaHei",sans-serif;
        box-shadow:0 6px 24px rgba(0,0,0,.25)
      }
      #scu-helper-panel .scu-title{font-weight:700;margin-bottom:6px}
      #scu-helper-panel #scu-status{opacity:.9;white-space:pre-line;margin-bottom:9px}
      #scu-helper-panel .scu-row{display:flex;gap:6px}
      #scu-helper-panel button,#scu-helper-panel select{
        border:0;border-radius:6px;padding:6px 8px;cursor:pointer
      }
      #scu-helper-panel button{background:#fff;color:#333}
      #scu-helper-panel select{background:#fff;color:#333}
    `;
    document.head.appendChild(style);
    document.body.appendChild(panel);

    const rate = panel.querySelector('#scu-rate');
    rate.value = String(CFG.playbackRate);

    panel.querySelector('#scu-play').addEventListener('click', async () => {
      const v = getActiveVideo();
      if (!v) return alert('暂未找到课程视频');
      applyRate(v);
      if (v.paused) {
        try { await v.play(); } catch (e) { alert('播放被浏览器阻止，请直接点击播放器。'); }
      } else {
        v.pause();
      }
      updatePanel();
    });

    rate.addEventListener('change', () => {
      CFG.playbackRate = Number(rate.value);
      localStorage.setItem('scu_helper_rate', String(CFG.playbackRate));
      applyRate(getActiveVideo());
    });

    // 🔥 修改点3：手动点击"下一节"按钮时弹出确认框
    panel.querySelector('#scu-next').addEventListener('click', () => goNextSection(true));
  }

  function updatePanel(extra = '') {
    if (!panel) return;

    const v = getActiveVideo();
    const current = getCurrentSectionItem();
    const items = getSectionItems();
    const idx = getCurrentSectionIndex();

    const status = panel.querySelector('#scu-status');
    if (!v) {
      status.textContent = `章节：${getSectionName(current) || '未识别'}\n视频：等待加载…${extra ? '\n' + extra : ''}`;
      return;
    }

    status.textContent =
      `章节：${getSectionName(current) || document.querySelector('.course_title .course_name')?.textContent?.trim() || '未识别'}\n` +
      `章节位置：${idx >= 0 ? idx + 1 : '?'} / ${items.length || '?'}\n` +
      `视频：${fmt(v.currentTime)} / ${fmt(v.duration)} · ${v.paused ? '暂停' : '播放'} · ${v.playbackRate}×` +
      (extra ? `\n${extra}` : '');
  }

  function scan() {
    createPanel();

    const key = `${location.href}|${document.querySelector('.course_title .course_name')?.textContent?.trim() || ''}`;
    if (key !== routeKey) {
      routeKey = key;
      log('页面/章节变化:', key);
    }

    const video = getActiveVideo();
    if (video) bindVideo(video);

    updatePanel();
  }

  // Vue 单页应用切换章节时，video 节点和 is-current 都可能被重建。
  const observer = new MutationObserver(throttle(scan, 300));
  observer.observe(document.documentElement, {
    childList: true,
    subtree: true,
    attributes: true,
    attributeFilter: ['class', 'src']
  });

  // 某些浏览器在用户首次交互之前会阻止 autoplay。
  document.addEventListener('pointerdown', () => {
    const v = getActiveVideo();
    if (v && v.paused && CFG.tryAutoplay) {
      setTimeout(() => tryPlay(v), 100);
    }
  }, { once: true, capture: true });

  scan();
  setInterval(scan, 2000);

  // 调试接口
  window.SCUHelper = {
    getActiveVideo,
    getSectionItems,
    getCurrentSectionItem,
    getNextSectionItem,
    goNextSection,
    scan
  };

  log('已启动。调试接口：window.SCUHelper');
})();