// ==UserScript==
// @name         陕西继续教育-视频辅助
// @version      5.1
// @description  隐身倍速、防暂停、自动静音、自动下一节、悬浮窗可拖拽
// @author       FengJB
// @match        *://mooc1.xidian.edu.cn/*
// @noframes
// @license      MIT
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    // ================= 全局配置 =================
    let currentRate = parseFloat(localStorage.getItem('xd_rate')) || 1.25;
    let isMuted = localStorage.getItem('xd_muted') === 'true';
    let autoNext = localStorage.getItem('xd_auto_next') === 'true';
    let targetVideo = null;
    // ==========================================

    // 拖拽功能函数
    function makeDraggable(elmnt, handle) {
        let pos1 = 0, pos2 = 0, pos3 = 0, pos4 = 0;

        if (handle) {
            handle.onmousedown = dragMouseDown;
        } else {
            elmnt.onmousedown = dragMouseDown;
        }

        function dragMouseDown(e) {
            e = e || window.event;
            e.preventDefault();
            pos3 = e.clientX;
            pos4 = e.clientY;
            document.onmouseup = closeDragElement;
            document.onmousemove = elementDrag;
        }

        function elementDrag(e) {
            e = e || window.event;
            e.preventDefault();
            pos1 = pos3 - e.clientX;
            pos2 = pos4 - e.clientY;
            pos3 = e.clientX;
            pos4 = e.clientY;

            // 计算新位置
            let newTop = elmnt.offsetTop - pos2;
            let newLeft = elmnt.offsetLeft - pos1;

            // 防止拖出屏幕外
            if (newTop < 0) newTop = 0;
            if (newLeft < 0) newLeft = 0;

            elmnt.style.top = newTop + "px";
            elmnt.style.left = newLeft + "px";
            elmnt.style.right = 'auto'; // 确保 right 属性不干扰
        }

        function closeDragElement() {
            document.onmouseup = null;
            document.onmousemove = null;
            // 保存位置到 localStorage
            localStorage.setItem('xd_panel_left', elmnt.offsetLeft);
            localStorage.setItem('xd_panel_top', elmnt.offsetTop);
        }
    }

    // 1. 创建悬浮控制面板 UI
    function createUI() {
        if (document.getElementById('xd-helper-panel')) return;

        const panel = document.createElement('div');
        panel.id = 'xd-helper-panel';
        panel.innerHTML = `
            <div id="xd-panel-header" style="font-weight: bold; margin-bottom: 8px; border-bottom: 1px solid #ccc; padding-bottom: 4px; display: flex; justify-content: space-between;">
                <span>📺 网课助手</span>
                <span id="xd-status" style="color: red;">未连接视频</span>
            </div>
            <div style="margin-bottom: 8px; display: flex; align-items: center;">
                <label style="margin-right: 8px;">倍速:</label>
                <select id="xd-rate-select" style="flex: 1; padding: 2px;">
                    <option value="1.0">1.0x (正常)</option>
                    <option value="1.25">1.25x</option>
                    <option value="1.5">1.5x</option>
                    <option value="1.75">1.75x</option>
                    <option value="2.0">2.0x</option>
                    <option value="20.0">20.0x (好像无效)</option>
                </select>
            </div>
            <div style="display: flex; align-items: center; margin-bottom: 8px;">
                <input type="checkbox" id="xd-mute-checkbox" style="margin-right: 8px; cursor: pointer;">
                <label for="xd-mute-checkbox" style="cursor: pointer;">静音播放</label>
            </div>
            <div style="display: flex; align-items: center; margin-bottom: 8px;">
                <input type="checkbox" id="xd-autonext-checkbox" style="margin-right: 8px; cursor: pointer;">
                <label for="xd-autonext-checkbox" style="cursor: pointer; color: #d93025;">播完自动下一节</label>
            </div>
            <button id="xd-next-btn" style="width: 100%; padding: 6px; background-color: #1890ff; color: white; border: none; border-radius: 4px; cursor: pointer; margin-bottom: 4px;">
                ⏭️ 手动切下一节
            </button>
            <div style="font-size: 12px; color: #666; text-align: center;">
                * 拖拽上方标题可移动面板
            </div>
        `;

        Object.assign(panel.style, {
            position: 'fixed', top: '80px', right: '20px', width: '220px',
            backgroundColor: 'rgba(255, 255, 255, 0.95)', border: '1px solid #1890ff',
            borderRadius: '8px', padding: '12px', zIndex: '999999',
            boxShadow: '0 4px 12px rgba(0,0,0,0.15)', fontFamily: 'sans-serif',
            fontSize: '14px', color: '#333'
        });

        // 恢复上次拖拽的位置
        const savedLeft = localStorage.getItem('xd_panel_left');
        const savedTop = localStorage.getItem('xd_panel_top');
        if (savedLeft !== null && savedTop !== null) {
            panel.style.left = savedLeft + 'px';
            panel.style.top = savedTop + 'px';
            panel.style.right = 'auto';
        }

        document.body.appendChild(panel);

        // 初始化拖拽功能，绑定在头部
        const header = document.getElementById('xd-panel-header');
        header.style.cursor = 'move';
        makeDraggable(panel, header);

        const rateSelect = document.getElementById('xd-rate-select');
        const muteCheckbox = document.getElementById('xd-mute-checkbox');
        const autoNextCheckbox = document.getElementById('xd-autonext-checkbox');
        const nextBtn = document.getElementById('xd-next-btn');

        rateSelect.value = currentRate;
        muteCheckbox.checked = isMuted;
        autoNextCheckbox.checked = autoNext;

        rateSelect.addEventListener('change', (e) => {
            currentRate = parseFloat(e.target.value);
            localStorage.setItem('xd_rate', currentRate);
            applySettings();
        });

        muteCheckbox.addEventListener('change', (e) => {
            isMuted = e.target.checked;
            localStorage.setItem('xd_muted', isMuted);
            applySettings();
        });

        autoNextCheckbox.addEventListener('change', (e) => {
            autoNext = e.target.checked;
            localStorage.setItem('xd_auto_next', autoNext);
        });

        nextBtn.addEventListener('click', () => {
            clickNextButton();
        });
    }

    // 2. 寻找并点击“下一节”按钮
    function clickNextButton() {
        let nextBtn = document.querySelector('.nextChapter') ||
                      document.querySelector('#prevNextFocusNext') ||
                      document.querySelector('.prev_next .next') ||
                      document.querySelector('a[onclick*="next"]');

        if (!nextBtn) {
            const links = document.querySelectorAll('a, div, button');
            for (let el of links) {
                if (el.innerText && el.innerText.trim() === '下一节') {
                    nextBtn = el;
                    break;
                }
            }
        }

        if (nextBtn) {
            console.log('【网课助手】找到下一节按钮，正在点击...', nextBtn);
            nextBtn.click();
        } else {
            console.warn('【网课助手】未找到下一节按钮，请检查页面结构。');
        }
    }

    // 3. 穿透 iframe 找视频
    function findVideo() {
        if (targetVideo && !targetVideo.paused) return targetVideo;
        let video = document.querySelector('video');
        if (video) return video;

        const iframes = document.querySelectorAll('iframe');
        for (let iframe of iframes) {
            try {
                const doc = iframe.contentDocument || iframe.contentWindow.document;
                video = doc.querySelector('video');
                if (video) return video;
                const innerIframes = doc.querySelectorAll('iframe');
                for (let inner of innerIframes) {
                    const innerDoc = inner.contentDocument || inner.contentWindow.document;
                    video = innerDoc.querySelector('video');
                    if (video) return video;
                }
            } catch (e) {}
        }
        return null;
    }

    // 4. 倍速隐身劫持
    function hijackVideo(video) {
        if (!video || video.dataset.xdHijacked) return;
        const win = video.ownerDocument.defaultView;
        const nativeDescriptor = Object.getOwnPropertyDescriptor(win.HTMLMediaElement.prototype, 'playbackRate');
        if (!nativeDescriptor) return;
        let internalRate = currentRate;
        try {
            Object.defineProperty(video, 'playbackRate', {
                configurable: true,
                get: function() { return 1.0; }, // 永远告诉平台是1.0
                set: function(val) {
                    if (val === 1.0) {
                        nativeDescriptor.set.call(video, internalRate);
                    } else {
                        internalRate = val;
                        nativeDescriptor.set.call(video, val);
                    }
                }
            });
            video.addEventListener('ratechange', (e) => e.stopImmediatePropagation(), true);
            video.dataset.xdHijacked = 'true';
            nativeDescriptor.set.call(video, currentRate);
        } catch (e) {}
    }

    function applySettings() {
        if (!targetVideo) return;
        targetVideo.muted = isMuted;
        targetVideo.volume = isMuted ? 0 : 1;
        try { targetVideo.playbackRate = currentRate; } catch(e) {}
    }

    // 5. 绑定视频事件
    function bindVideoEvents(video) {
        if (video.dataset.xdBound) return;
        video.dataset.xdBound = 'true';

        const statusEl = document.getElementById('xd-status');
        if (statusEl) { statusEl.innerText = '已连接(隐身) ✅'; statusEl.style.color = 'green'; }

        hijackVideo(video);
        applySettings();

        // 核心：监听视频播放结束事件
        video.addEventListener('ended', () => {
            console.log('【网课助手】当前视频播放结束！');
            if (autoNext) {
                if (statusEl) { statusEl.innerText = '3秒后自动跳转...'; statusEl.style.color = 'blue'; }
                setTimeout(() => {
                    clickNextButton();
                }, 3000);
            } else {
                if (statusEl) { statusEl.innerText = '等待手动切下一节'; statusEl.style.color = 'orange'; }
            }
        });

        // 防切屏暂停机制
        video.addEventListener('pause', () => {
            if (!video.ended) {
                setTimeout(() => {
                    video.play().catch(e => {});
                }, 1000);
            }
        });

        video.play().catch(() => {
            console.log('【网课助手】自动播放被阻止，请手动点击播放');
        });
    }

    // 6. 主循环检测
    function loop() {
        createUI();
        const video = findVideo();
        if (video && video !== targetVideo) {
            targetVideo = video;
            bindVideoEvents(targetVideo);
        } else if (targetVideo) {
            if (targetVideo.muted !== isMuted) targetVideo.muted = isMuted;
        }
        setTimeout(loop, 2000);
    }

    // 7. 防失焦暂停
    const blockEvent = (e) => e.stopImmediatePropagation();
    ['blur', 'visibilitychange'].forEach(ev => window.addEventListener(ev, blockEvent, true));

    window.addEventListener('load', loop);
})();