// ==UserScript==
// @name         Markdown 阅读器 & 编辑器 (分屏实时预览) – 可拖拽工具栏（常规字体+切换）
// @namespace    http://tampermonkey.net/
// @version      5.7
// @description  拖入 .md 文件，分屏预览+编辑，样式按钮平铺，面板可拖拽，所有按钮点击切换，加粗预览更明显，左侧预览区支持文字复制，自动清除尾部垃圾行（逐行删除），启动即分屏
// @author       MRBANK (modified by xizi)
// @match        file:///*
// @grant        GM_addStyle
// @run-at       document-start
// @icon         data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSIyNCIgaGVpZ2h0PSIyNCIgdmlld0JveD0iMCAwIDI0IDI0Ij48cmVjdCB3aWR0aD0iMjQiIGhlaWdodD0iMjQiIHJ4PSI1IiBmaWxsPSIjMjgyYTM2IiBzdHJva2U9IiM1MGZhN2IiIHN0cm9rZS13aWR0aD0iMS41Ii8+PHRleHQgeD0iMTIiIHk9IjE2LjUiIHRleHQtYW5jaG9yPSJtaWRkbGUiIGZvbnQtZmFtaWx5PSJBcmlhbCwgc2Fucy1zZXJpZiIgZm9udC13ZWlnaHQ9ImJvbGQiIGZvbnQtc2l6ZT0iMTQiIGZpbGw9IiM1MGZhN2IiPk08L3RleHQ+PC9zdmc+
// @license All Rights Reserved
// ==/UserScript==

(function() {
    'use strict';

    // ---------- 全局状态 ----------
    let currentSource = '';
    let currentFileName = 'document';

    // ---------- DOM 引用 ----------
    const panel = document.createElement('div');
    panel.id = 'md-control-panel';

    // 样式按钮定义（增加 data-action 属性）
    const styleActions = [
        { label: 'H1', action: 'h1' },
        { label: 'H2', action: 'h2' },
        { label: 'H3', action: 'h3' },
        { label: 'B', action: 'bold' },
        { label: 'I', action: 'italic' },
        { label: '`', action: 'code' },
        { label: '代码块', action: 'codeblock' },
        { label: '引用', action: 'quote' },
        { label: '列表', action: 'ul' },
        { label: '有序', action: 'ol' },
        { label: '链接', action: 'link' },
        { label: '图片', action: 'image' },
        { label: '🎨', action: 'color' }
    ];

    // 创建按钮，只设置类、文本和 data-action，不绑定事件
    styleActions.forEach(item => {
        const btn = document.createElement('button');
        btn.className = 'md-btn-control';
        btn.textContent = item.label;
        btn.dataset.action = item.action;
        panel.appendChild(btn);
    });

    // 保存按钮
    const btnSave = document.createElement('button');
    btnSave.className = 'md-btn-control';
    btnSave.textContent = '保存';
    panel.appendChild(btnSave);

    const dropOverlay = document.createElement('div');
    dropOverlay.id = 'md-drop-overlay';
    dropOverlay.innerHTML = `
        <div class="md-drop-content">
            <div class="md-drop-icon">📄</div>
            <div class="md-drop-text">将 Markdown 文件拖放到此处</div>
            <div class="md-drop-hint">支持 .md .markdown .txt</div>
        </div>
    `;

    // ---------- 分屏元素 ----------
    let previewPane = null;
    let textarea = null;
    let splitter = null;
    let container = null;

    // ---------- 样式 ----------
    GM_addStyle(`
        #md-control-panel {
            position: fixed;
            left: calc(100vw - 12px - auto);
            top: 12px;
            z-index: 2147483647;
            display: flex;
            flex-wrap: wrap;
            gap: 4px;
            background: #2b2b2b;
            padding: 6px 8px;
            border-radius: 8px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.3);
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
            border: 1px solid #444;
            max-width: 90vw;
            justify-content: flex-end;
            cursor: grab;
            user-select: none;
        }
        #md-control-panel.dragging { cursor: grabbing; }
        .md-btn-control {
            background: transparent;
            color: #999;
            border: none;
            padding: 4px 12px;
            font-size: 13px;
            font-weight: 500;
            cursor: pointer;
            border-radius: 6px;
            transition: all 0.2s ease-in-out;
            line-height: 1.5;
            white-space: nowrap;
        }
        .md-btn-control:hover { color: #fff; background: #3a3a3a; }
        .md-btn-control.active {
            background: #555;
            color: #fff;
            box-shadow: 0 2px 4px rgba(0,0,0,0.2);
        }

        #md-drop-overlay {
            position: fixed;
            top: 0; left: 0; right: 0; bottom: 0;
            z-index: 2147483646;
            display: flex;
            align-items: center;
            justify-content: center;
            background: rgba(40, 42, 54, 0.95);
            color: #f8f8f2;
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
            transition: opacity 0.3s;
            pointer-events: none;
            opacity: 0;
        }
        #md-drop-overlay.show { opacity: 1; pointer-events: auto; }
        .md-drop-content {
            text-align: center;
            border: 3px dashed #50fa7b;
            padding: 60px 80px;
            border-radius: 24px;
            background: rgba(30, 31, 41, 0.8);
        }
        .md-drop-icon { font-size: 72px; margin-bottom: 20px; }
        .md-drop-text { font-size: 28px; font-weight: 600; margin-bottom: 10px; }
        .md-drop-hint { font-size: 16px; color: #999; }

        body {
            margin: 0;
            padding: 0;
            background: #1e1f29;
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
        }
        .md-split-container {
            display: flex;
            height: 100vh;
            width: 100vw;
            background: #1e1f29;
            overflow: hidden;
            user-select: none;
        }
        .md-preview-pane, .md-editor-pane {
            flex: 1 1 0;
            height: 100%;
            overflow: auto;
            padding: 20px;
            box-sizing: border-box;
        }
        .md-preview-pane {
            background: #282a36;
            color: #f8f8f2;
            overflow-y: auto;
            /* 允许选择文本，便于复制 */
            user-select: text;
            -webkit-user-select: text;
            -moz-user-select: text;
        }
        .md-preview-pane .md-rendered {
            max-width: 900px;
            margin: 0 auto;
            line-height: 1.6;
            font-weight: 400;
        }
        .md-editor-pane {
            background: #282a36;
            border-left: 1px solid #444;
        }
        .md-editor-pane textarea {
            width: 100%;
            height: 100%;
            background: transparent;
            color: #f8f8f2;
            font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
            font-size: 14px;
            line-height: 1.6;
            border: none;
            resize: none;
            outline: none;
            padding: 0;
            white-space: pre-wrap;
            word-wrap: break-word;
            tab-size: 4;
        }
        .md-editor-pane textarea:focus { box-shadow: none; }

        .md-splitter {
            flex: 0 0 6px;
            background: #444;
            cursor: col-resize;
            transition: background 0.15s;
            position: relative;
            z-index: 10;
        }
        .md-splitter:hover,
        .md-splitter.dragging { background: #50fa7b; }
        .md-splitter::after {
            content: '⋮';
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            color: #888;
            font-size: 16px;
            line-height: 1;
        }

        /* 预览区标题样式 */
        .md-preview-pane .md-rendered h1,
        .md-preview-pane .md-rendered h2,
        .md-preview-pane .md-rendered h3,
        .md-preview-pane .md-rendered h4,
        .md-preview-pane .md-rendered h5,
        .md-preview-pane .md-rendered h6 {
            color: #bd93f9;
            margin-top: 24px;
            margin-bottom: 16px;
            line-height: 1.25;
        }
        .md-preview-pane .md-rendered h1 { font-size: 2em; border-bottom: 1px solid #444; padding-bottom: .3em; }
        .md-preview-pane .md-rendered h2 { font-size: 1.5em; border-bottom: 1px solid #444; padding-bottom: .3em; }
        .md-preview-pane .md-rendered p { margin-bottom: 16px; }
        .md-preview-pane .md-rendered a { color: #8be9fd; text-decoration: none; }
        .md-preview-pane .md-rendered a:hover { text-decoration: underline; }
        .md-preview-pane .md-rendered code {
            background: #44475a;
            padding: 0.2em 0.4em;
            margin: 0;
            font-size: 85%;
            border-radius: 3px;
            font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
            color: #50fa7b;
        }
        .md-preview-pane .md-rendered pre {
            background: #1e1f29;
            border-radius: 6px;
            padding: 16px;
            overflow: auto;
            line-height: 1.45;
            font-size: 14px;
        }
        .md-preview-pane .md-rendered pre code {
            background: transparent;
            padding: 0;
            color: #f8f8f2;
        }
        .md-hl-kw { color: #ff79c6; }
        .md-hl-str { color: #f1fa8c; }
        .md-hl-num { color: #bd93f9; }
        .md-hl-cmt { color: #6272a4; font-style: italic; }
        .md-preview-pane .md-rendered blockquote {
            border-left: 4px solid #bd93f9;
            padding-left: 16px;
            margin: 0 0 16px 0;
            color: #b0b0b0;
        }
        .md-preview-pane .md-rendered table {
            border-collapse: collapse;
            width: 100%;
            margin-bottom: 16px;
        }
        .md-preview-pane .md-rendered table th,
        .md-preview-pane .md-rendered table td {
            border: 1px solid #444;
            padding: 8px 12px;
        }
        .md-preview-pane .md-rendered table th { background: #44475a; font-weight: 400; }
        .md-preview-pane .md-rendered table tr:nth-child(even) { background: rgba(40, 42, 54, 0.5); }
        .md-preview-pane .md-rendered img {
            max-width: 100%;
            border-radius: 4px;
            margin: 10px 0;
        }
        .md-preview-pane .md-rendered hr {
            border: 0;
            height: 1px;
            background-image: linear-gradient(to right, rgba(255, 255, 255, 0), rgba(255, 255, 255, 0.2), rgba(255, 255, 255, 0));
            margin: 2em 0;
        }

        /* 增强加粗样式，使其更明显 */
        .md-preview-pane .md-rendered strong {
            font-weight: 700;
            color: #ffffff;
        }

        .md-preview-pane::-webkit-scrollbar,
        .md-editor-pane::-webkit-scrollbar {
            width: 8px;
        }
        .md-preview-pane::-webkit-scrollbar-track,
        .md-editor-pane::-webkit-scrollbar-track {
            background: #1e1f29;
        }
        .md-preview-pane::-webkit-scrollbar-thumb,
        .md-editor-pane::-webkit-scrollbar-thumb {
            background: #555;
            border-radius: 4px;
        }
        .md-preview-pane::-webkit-scrollbar-thumb:hover,
        .md-editor-pane::-webkit-scrollbar-thumb:hover {
            background: #777;
        }
    `);

    // ---------- 面板拖拽逻辑 ----------
    let isDragging = false;
    let dragStartX = 0, dragStartY = 0;
    let panelStartLeft = 0, panelStartTop = 0;

    function initPanelPosition() {
        const saved = localStorage.getItem('mdPanelPosition');
        if (saved) {
            try {
                const pos = JSON.parse(saved);
                if (pos.left !== undefined && pos.top !== undefined) {
                    panel.style.left = pos.left + 'px';
                    panel.style.top = pos.top + 'px';
                    return;
                }
            } catch (e) {}
        }
        const panelWidth = panel.offsetWidth || 200;
        const defaultLeft = window.innerWidth - panelWidth - 12;
        panel.style.left = defaultLeft + 'px';
        panel.style.top = '12px';
    }

    function savePanelPosition() {
        const rect = panel.getBoundingClientRect();
        const pos = { left: rect.left, top: rect.top };
        localStorage.setItem('mdPanelPosition', JSON.stringify(pos));
    }

    function onPanelMouseDown(e) {
        if (e.target.closest('.md-btn-control')) return;
        isDragging = true;
        const rect = panel.getBoundingClientRect();
        panelStartLeft = rect.left;
        panelStartTop = rect.top;
        dragStartX = e.clientX;
        dragStartY = e.clientY;
        panel.classList.add('dragging');
        document.body.style.cursor = 'grabbing';
        e.preventDefault();
    }

    function onDocumentMouseMove(e) {
        if (!isDragging) return;
        const dx = e.clientX - dragStartX;
        const dy = e.clientY - dragStartY;
        let newLeft = panelStartLeft + dx;
        let newTop = panelStartTop + dy;
        const panelWidth = panel.offsetWidth;
        const panelHeight = panel.offsetHeight;
        newLeft = Math.max(0, Math.min(window.innerWidth - panelWidth, newLeft));
        newTop = Math.max(0, Math.min(window.innerHeight - panelHeight, newTop));
        panel.style.left = newLeft + 'px';
        panel.style.top = newTop + 'px';
    }

    function onDocumentMouseUp(e) {
        if (isDragging) {
            isDragging = false;
            panel.classList.remove('dragging');
            document.body.style.cursor = '';
            savePanelPosition();
        }
    }

    // ---------- 工具：清洗尾部垃圾行（逐行检查） ----------
    function cleanTrailingGarbage(text) {
        if (!text) return text;
        const lines = text.split('\n');
        // 定义垃圾关键词列表（完全匹配一行，忽略大小写和首尾空格）
        const garbageWords = [
            'H1', 'H2', 'H3', 'B', 'I', '`',
            '代码块', '引用', '列表', '有序', '链接', '图片',
            '🎨', '保存', '📄',
            '将 Markdown 文件拖放到此处',
            '支持 .md .markdown .txt'
        ];
        // 转义正则特殊字符
        const escapedWords = garbageWords.map(w => w.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'));
        const regex = new RegExp('^\\s*(' + escapedWords.join('|') + ')\\s*$', 'i');

        // 从末尾开始向前查找，删除所有连续匹配的行
        let endIndex = lines.length;
        for (let i = lines.length - 1; i >= 0; i--) {
            const line = lines[i];
            if (regex.test(line)) {
                endIndex = i;
            } else {
                break;
            }
        }
        if (endIndex < lines.length) {
            // 删除从 endIndex 开始到末尾的所有行
            const cleaned = lines.slice(0, endIndex).join('\n');
            return cleaned;
        }
        return text;
    }

    // ---------- 核心功能 ----------
    function init() {
        // ===== 只匹配本地 .md 文件 =====
        if (!window.location.pathname.match(/\.md$/i)) {
            return; // 非 .md 文件静默退出
        }

        document.body.appendChild(panel);
        document.body.appendChild(dropOverlay);

        initPanelPosition();

        panel.addEventListener('mousedown', onPanelMouseDown);
        document.addEventListener('mousemove', onDocumentMouseMove);
        document.addEventListener('mouseup', onDocumentMouseUp);

        panel.addEventListener('click', function(e) {
            const btn = e.target.closest('.md-btn-control');
            if (!btn) return;
            const action = btn.dataset.action;
            if (!action) return;
            handleStyleAction(action);
        });

        const autoContent = getAutoContent();
        if (autoContent) {
            currentSource = autoContent;
            currentFileName = getDocumentTitle();
            buildSplitView();
        } else {
            // 无内容时直接创建空白分屏，不显示拖放覆盖层
            currentSource = '';
            currentFileName = 'untitled';
            buildSplitView();
        }
        hideDropOverlay(); // 确保覆盖层始终隐藏

        document.addEventListener('dragover', handleDragOver, false);
        document.addEventListener('drop', handleDrop, false);
        document.addEventListener('dragenter', handleDragEnter, false);
        document.addEventListener('dragleave', handleDragLeave, false);

        btnSave.addEventListener('click', async () => {
            if (!currentSource) {
                alert('没有内容可保存！');
                return;
            }
            // 保存前：从 textarea 获取最新内容并清洗
            if (textarea) {
                let content = textarea.value;
                content = cleanTrailingGarbage(content); // 清洗尾部垃圾
                // 更新 textarea 和 currentSource 为清洗后的内容
                textarea.value = content;
                currentSource = content;
                updatePreview(); // 刷新预览
            }
            await saveMarkdownFile();
        });

        window.addEventListener('beforeunload', (e) => {
            if (textarea && textarea.value !== currentSource) {
                const msg = '您有未保存的编辑内容，确定离开吗？';
                e.returnValue = msg;
                return msg;
            }
        });

        window.addEventListener('resize', () => {
            const rect = panel.getBoundingClientRect();
            const maxX = window.innerWidth - rect.width;
            const maxY = window.innerHeight - rect.height;
            let needUpdate = false;
            let newLeft = rect.left;
            let newTop = rect.top;
            if (rect.left > maxX) { newLeft = Math.max(0, maxX); needUpdate = true; }
            if (rect.top > maxY) { newTop = Math.max(0, maxY); needUpdate = true; }
            if (needUpdate) {
                panel.style.left = newLeft + 'px';
                panel.style.top = newTop + 'px';
                savePanelPosition();
            }
        });
    }

    function getAutoContent() {
        const url = window.location.href;
        const isLocalFile = window.location.protocol === 'file:';
        const isMarkdownFile = url.endsWith('.md') || url.endsWith('.markdown') || url.endsWith('.txt');
        const isPlainText = document.body ? (document.body.childElementCount === 1 && document.body.firstElementChild && document.body.firstElementChild.tagName === 'PRE') : false;

        if (isLocalFile || isMarkdownFile || isPlainText) {
            let content = document.body.innerText || '';
            content = cleanTrailingGarbage(content);
            return content;
        }
        return '';
    }

    function getDocumentTitle() {
        const pathname = decodeURIComponent(window.location.pathname || 'document');
        const filename = pathname.split('/').pop() || 'document';
        return filename.replace(/\.(md|markdown|txt)$/i, '') || 'document';
    }

    // ---------- 构建分屏视图 ----------
    function buildSplitView() {
        document.body.innerHTML = '';
        document.body.style.margin = '0';
        document.body.style.padding = '0';
        document.body.style.background = '#1e1f29';

        container = document.createElement('div');
        container.className = 'md-split-container';

        previewPane = document.createElement('div');
        previewPane.className = 'md-preview-pane';
        const previewInner = document.createElement('div');
        previewInner.className = 'md-rendered';
        previewPane.appendChild(previewInner);

        splitter = document.createElement('div');
        splitter.className = 'md-splitter';

        const editorPane = document.createElement('div');
        editorPane.className = 'md-editor-pane';
        textarea = document.createElement('textarea');
        textarea.value = currentSource;
        textarea.spellcheck = false;
        editorPane.appendChild(textarea);

        container.appendChild(previewPane);
        container.appendChild(splitter);
        container.appendChild(editorPane);

        document.body.appendChild(container);
        document.body.appendChild(panel);

        textarea.addEventListener('input', function() {
            currentSource = this.value;
            updatePreview();
        });

        updatePreview();

        let isResizing = false;
        let startX = 0;
        let startLeftWidth = 0;

        splitter.addEventListener('mousedown', function(e) {
            isResizing = true;
            startX = e.clientX;
            startLeftWidth = previewPane.getBoundingClientRect().width;
            splitter.classList.add('dragging');
            document.body.style.cursor = 'col-resize';
            e.preventDefault();
        });

        document.addEventListener('mousemove', function(e) {
            if (!isResizing) return;
            const deltaX = e.clientX - startX;
            const containerWidth = container.getBoundingClientRect().width;
            const splitterWidth = splitter.getBoundingClientRect().width;
            let newLeftWidth = Math.min(
                Math.max(startLeftWidth + deltaX, containerWidth * 0.1),
                containerWidth * 0.9 - splitterWidth
            );
            const rightWidth = containerWidth - newLeftWidth - splitterWidth;
            previewPane.style.flex = `0 0 ${newLeftWidth}px`;
            editorPane.style.flex = `0 0 ${rightWidth}px`;
        });

        document.addEventListener('mouseup', function() {
            if (isResizing) {
                isResizing = false;
                splitter.classList.remove('dragging');
                document.body.style.cursor = '';
            }
        });

        hideDropOverlay();
    }

    function updatePreview() {
        if (!previewPane) return;
        const renderDiv = previewPane.querySelector('.md-rendered');
        if (renderDiv) {
            const html = MarkdownParser.parse(currentSource);
            renderDiv.innerHTML = html;
        }
    }

    // ---------- 拖放处理 ----------
    function handleDragOver(e) {
        e.preventDefault();
        e.dataTransfer.dropEffect = 'copy';
        showDropOverlay();
    }
    function handleDragEnter(e) {
        e.preventDefault();
        showDropOverlay();
    }
    function handleDragLeave(e) {
        e.preventDefault();
        if (e.relatedTarget === null) {
            hideDropOverlay();
        }
    }
    function handleDrop(e) {
        e.preventDefault();
        hideDropOverlay();

        const files = e.dataTransfer.files;
        if (files.length === 0) return;

        const file = files[0];
        const ext = file.name.split('.').pop().toLowerCase();
        if (!['md', 'markdown', 'txt'].includes(ext)) {
            alert('请拖入 .md .markdown 或 .txt 文件！');
            return;
        }

        const reader = new FileReader();
        reader.onload = function(event) {
            let content = event.target.result;
            content = cleanTrailingGarbage(content);
            currentSource = content;
            currentFileName = file.name.replace(/\.[^.]+$/, '') || 'document';
            if (textarea) {
                textarea.value = currentSource;
                updatePreview();
            } else {
                buildSplitView();
            }
            hideDropOverlay();
        };
        reader.onerror = function() {
            alert('读取文件失败，请重试。');
        };
        reader.readAsText(file, 'UTF-8');
    }

    function showDropOverlay() {
        dropOverlay.style.opacity = '1';
        dropOverlay.style.pointerEvents = 'auto';
    }
    function hideDropOverlay() {
        dropOverlay.style.opacity = '0';
        dropOverlay.style.pointerEvents = 'none';
    }

    // ---------- 保存为 .md ----------
    async function saveMarkdownFile() {
        // 再次清洗，确保万无一失
        if (textarea) {
            let content = textarea.value;
            content = cleanTrailingGarbage(content);
            textarea.value = content;
            currentSource = content;
            updatePreview();
        }
        if (!currentSource) return;

        if ('showSaveFilePicker' in window) {
            try {
                const handle = await window.showSaveFilePicker({
                    suggestedName: currentFileName + '.md',
                    types: [{
                        description: 'Markdown 文件',
                        accept: { 'text/markdown': ['.md'] }
                    }]
                });
                const writable = await handle.createWritable();
                await writable.write('\ufeff' + currentSource);
                await writable.close();
                alert('✅ 文件已保存！');
                return;
            } catch (err) {
                if (err.name !== 'AbortError') {
                    console.warn('保存失败，回退到下载', err);
                } else {
                    return;
                }
            }
        }

        const blob = new Blob(['\ufeff' + currentSource], { type: 'text/markdown;charset=utf-8' });
        const url = URL.createObjectURL(blob);
        const a = document.createElement('a');
        a.href = url;
        a.download = currentFileName + '.md';
        document.body.appendChild(a);
        a.click();
        a.remove();
        URL.revokeObjectURL(url);
    }

    // ========== 样式工具栏核心逻辑（全部支持切换） ==========

    // 辅助：切换行内标记（加粗、倾斜、代码）
    function toggleInlineMark(text, mark) {
        if (!text) return mark + mark;
        if (text.startsWith(mark) && text.endsWith(mark)) {
            return text.slice(mark.length, -mark.length);
        }
        return mark + text + mark;
    }

    // 辅助：对每行应用或移除前缀（引用、列表、有序）
    function toggleLinePrefix(text, prefix, regex) {
        if (!text) return prefix + ' ';
        const lines = text.split('\n');
        const newLines = lines.map(line => {
            const trimmed = line;
            if (regex) {
                // 有序列表：检测是否以数字+.开头
                if (regex.test(trimmed)) {
                    return trimmed.replace(regex, '');
                } else {
                    return prefix + trimmed;
                }
            } else {
                if (trimmed.startsWith(prefix)) {
                    return trimmed.slice(prefix.length);
                } else {
                    return prefix + trimmed;
                }
            }
        });
        return newLines.join('\n');
    }

    // 辅助：检测并移除包裹（代码块、链接、图片、颜色）
    function toggleWrapped(text, open, close, stripOpen, stripClose) {
        if (!text) return open + close; // 空选区插入占位
        // 检查是否被 open 和 close 包裹
        if (text.startsWith(open) && text.endsWith(close)) {
            let inner = text.slice(open.length, -close.length);
            // 对于链接/图片，可能还有额外处理，但通用剥离
            return inner;
        } else {
            return open + text + close;
        }
    }

    // 专门处理颜色：检测是否被 <span style="color:..."> 包裹
    function toggleColor(text) {
        if (!text) return '<span style="color: #000000;">彩色文本</span>';
        // 检测是否被 <span style="color: ..."> ... </span> 包裹
        const match = text.match(/^<span style="color:\s*[^"]+;">(.*)<\/span>$/s);
        if (match) {
            return match[1]; // 剥离标签
        } else {
            // 不包裹，弹出颜色选择器由外部处理，这里返回null表示需要弹出选择器
            return null;
        }
    }

    function handleStyleAction(action) {
        if (!textarea) return;
        const ta = textarea;
        const start = ta.selectionStart;
        const end = ta.selectionEnd;
        const selected = ta.value.substring(start, end);
        let replacement = '';
        let cursorOffset = 0;

        // 处理标题（已有切换）
        const headingMap = { 'h1': 1, 'h2': 2, 'h3': 3 };
        if (action in headingMap) {
            const level = headingMap[action];
            if (!selected) {
                // 空选区：作用于当前行
                const lineStart = ta.value.lastIndexOf('\n', start - 1) + 1;
                let lineEnd = ta.value.indexOf('\n', start);
                if (lineEnd === -1) lineEnd = ta.value.length;
                const lineText = ta.value.substring(lineStart, lineEnd);
                const newLine = toggleHeadingLine(lineText, level);
                ta.value = ta.value.substring(0, lineStart) + newLine + ta.value.substring(lineEnd);
                ta.selectionStart = ta.selectionEnd = lineStart + newLine.length;
            } else {
                // 有选区：处理每行
                const lines = selected.split('\n');
                const newLines = lines.map(line => toggleHeadingLine(line, level));
                replacement = newLines.join('\n');
                ta.value = ta.value.substring(0, start) + replacement + ta.value.substring(end);
                ta.selectionStart = start;
                ta.selectionEnd = start + replacement.length;
            }
            ta.focus();
            const event = new Event('input', { bubbles: true });
            ta.dispatchEvent(event);
            currentSource = ta.value;
            updatePreview();
            return;
        }

        // 辅助：应用切换并更新
        function applyReplacement(repl, cursorPos) {
            ta.value = ta.value.substring(0, start) + repl + ta.value.substring(end);
            if (cursorPos !== undefined) {
                ta.selectionStart = ta.selectionEnd = cursorPos;
            } else {
                ta.selectionStart = start;
                ta.selectionEnd = start + repl.length;
            }
            ta.focus();
            const event = new Event('input', { bubbles: true });
            ta.dispatchEvent(event);
            currentSource = ta.value;
            updatePreview();
        }

        switch (action) {
            case 'bold':
                replacement = toggleInlineMark(selected, '**');
                if (!selected) cursorOffset = 2;
                applyReplacement(replacement, start + cursorOffset);
                break;
            case 'italic':
                replacement = toggleInlineMark(selected, '*');
                if (!selected) cursorOffset = 1;
                applyReplacement(replacement, start + cursorOffset);
                break;
            case 'code':
                replacement = toggleInlineMark(selected, '`');
                if (!selected) cursorOffset = 1;
                applyReplacement(replacement, start + cursorOffset);
                break;
            case 'codeblock': {
                if (!selected) {
                    replacement = '```\n\n```';
                    applyReplacement(replacement, start + 4);
                } else {
                    // 检测是否被 ``` 包裹
                    if (selected.startsWith('```\n') && selected.endsWith('\n```')) {
                        // 移除最外层的 ```
                        let inner = selected.slice(4, -4); // 去掉 ```\n 和 \n```
                        // 如果内部开头有换行，可保留
                        applyReplacement(inner, start);
                    } else {
                        replacement = '```\n' + selected + '\n```';
                        applyReplacement(replacement, start + replacement.length);
                    }
                }
                break;
            }
            case 'quote': {
                if (!selected) {
                    // 空选区：作用于当前行
                    const lineStart = ta.value.lastIndexOf('\n', start - 1) + 1;
                    let lineEnd = ta.value.indexOf('\n', start);
                    if (lineEnd === -1) lineEnd = ta.value.length;
                    const lineText = ta.value.substring(lineStart, lineEnd);
                    // 检测是否以 '> ' 开头
                    if (lineText.startsWith('> ')) {
                        replacement = lineText.slice(2);
                    } else {
                        replacement = '> ' + lineText;
                    }
                    ta.value = ta.value.substring(0, lineStart) + replacement + ta.value.substring(lineEnd);
                    ta.selectionStart = ta.selectionEnd = lineStart + replacement.length;
                } else {
                    // 有选区：处理每行
                    const lines = selected.split('\n');
                    const newLines = lines.map(line => {
                        if (line.startsWith('> ')) return line.slice(2);
                        else return '> ' + line;
                    });
                    replacement = newLines.join('\n');
                    ta.value = ta.value.substring(0, start) + replacement + ta.value.substring(end);
                    ta.selectionStart = start;
                    ta.selectionEnd = start + replacement.length;
                }
                ta.focus();
                const ev = new Event('input', { bubbles: true });
                ta.dispatchEvent(ev);
                currentSource = ta.value;
                updatePreview();
                break;
            }
            case 'ul': {
                if (!selected) {
                    const lineStart = ta.value.lastIndexOf('\n', start - 1) + 1;
                    let lineEnd = ta.value.indexOf('\n', start);
                    if (lineEnd === -1) lineEnd = ta.value.length;
                    const lineText = ta.value.substring(lineStart, lineEnd);
                    if (lineText.startsWith('- ')) {
                        replacement = lineText.slice(2);
                    } else {
                        replacement = '- ' + lineText;
                    }
                    ta.value = ta.value.substring(0, lineStart) + replacement + ta.value.substring(lineEnd);
                    ta.selectionStart = ta.selectionEnd = lineStart + replacement.length;
                } else {
                    const lines = selected.split('\n');
                    const newLines = lines.map(line => {
                        if (line.startsWith('- ')) return line.slice(2);
                        else return '- ' + line;
                    });
                    replacement = newLines.join('\n');
                    ta.value = ta.value.substring(0, start) + replacement + ta.value.substring(end);
                    ta.selectionStart = start;
                    ta.selectionEnd = start + replacement.length;
                }
                ta.focus();
                const ev = new Event('input', { bubbles: true });
                ta.dispatchEvent(ev);
                currentSource = ta.value;
                updatePreview();
                break;
            }
            case 'ol': {
                const olRegex = /^\d+\.\s/;
                if (!selected) {
                    const lineStart = ta.value.lastIndexOf('\n', start - 1) + 1;
                    let lineEnd = ta.value.indexOf('\n', start);
                    if (lineEnd === -1) lineEnd = ta.value.length;
                    const lineText = ta.value.substring(lineStart, lineEnd);
                    if (olRegex.test(lineText)) {
                        replacement = lineText.replace(olRegex, '');
                    } else {
                        replacement = '1. ' + lineText;
                    }
                    ta.value = ta.value.substring(0, lineStart) + replacement + ta.value.substring(lineEnd);
                    ta.selectionStart = ta.selectionEnd = lineStart + replacement.length;
                } else {
                    const lines = selected.split('\n');
                    const newLines = lines.map(line => {
                        if (olRegex.test(line)) {
                            return line.replace(olRegex, '');
                        } else {
                            return '1. ' + line;
                        }
                    });
                    replacement = newLines.join('\n');
                    ta.value = ta.value.substring(0, start) + replacement + ta.value.substring(end);
                    ta.selectionStart = start;
                    ta.selectionEnd = start + replacement.length;
                }
                ta.focus();
                const ev = new Event('input', { bubbles: true });
                ta.dispatchEvent(ev);
                currentSource = ta.value;
                updatePreview();
                break;
            }
            case 'link': {
                if (!selected) {
                    replacement = '[](url)';
                    applyReplacement(replacement, start + 1);
                } else {
                    // 检测是否匹配 [text](url)
                    const linkMatch = selected.match(/^\[([^\]]+)\]\(([^)]+)\)$/);
                    if (linkMatch) {
                        // 提取文本
                        replacement = linkMatch[1];
                        applyReplacement(replacement, start);
                    } else {
                        replacement = '[' + selected + '](url)';
                        applyReplacement(replacement, start + replacement.length);
                    }
                }
                break;
            }
            case 'image': {
                if (!selected) {
                    replacement = '![](url)';
                    applyReplacement(replacement, start + 2);
                } else {
                    const imgMatch = selected.match(/^!\[([^\]]*)\]\(([^)]+)\)$/);
                    if (imgMatch) {
                        replacement = imgMatch[1];
                        applyReplacement(replacement, start);
                    } else {
                        replacement = '![' + selected + '](url)';
                        applyReplacement(replacement, start + replacement.length);
                    }
                }
                break;
            }
            case 'color': {
                if (!selected) {
                    // 空选区：插入默认彩色文本，并弹出选择器？这里简单插入占位
                    replacement = '<span style="color: #000000;">彩色文本</span>';
                    applyReplacement(replacement, start + replacement.length);
                    break;
                }
                // 检测是否已被颜色标签包裹
                const colorMatch = selected.match(/^<span style="color:\s*[^"]+;">(.*)<\/span>$/s);
                if (colorMatch) {
                    // 移除颜色标签
                    replacement = colorMatch[1];
                    applyReplacement(replacement, start);
                } else {
                    // 弹出颜色选择器
                    const oldInput = document.getElementById('md-color-input');
                    if (oldInput) oldInput.remove();
                    const input = document.createElement('input');
                    input.type = 'color';
                    input.id = 'md-color-input';
                    input.style.position = 'fixed';
                    input.style.left = '-9999px';
                    input.style.top = '-9999px';
                    document.body.appendChild(input);
                    input.addEventListener('change', function(e) {
                        const color = this.value;
                        const repl = `<span style="color: ${color};">${selected}</span>`;
                        ta.value = ta.value.substring(0, start) + repl + ta.value.substring(end);
                        ta.selectionStart = start;
                        ta.selectionEnd = start + repl.length;
                        ta.focus();
                        const ev = new Event('input', { bubbles: true });
                        ta.dispatchEvent(ev);
                        currentSource = ta.value;
                        updatePreview();
                        this.remove();
                    });
                    input.addEventListener('blur', function() {
                        if (this.parentNode) this.remove();
                    });
                    input.click();
                    return; // 异步处理，不继续
                }
                break;
            }
            default:
                return;
        }
    }

    // 切换标题（保持原有逻辑）
    function toggleHeadingLine(line, level) {
        const leadingSpaces = line.match(/^(\s*)/)[0];
        const trimmed = line.trimLeft();
        const match = trimmed.match(/^(#+)\s/);
        if (match) {
            const currentLevel = match[1].length;
            const content = trimmed.substring(match[0].length);
            if (currentLevel === level) {
                return leadingSpaces + content;
            } else {
                return leadingSpaces + '#'.repeat(level) + ' ' + content;
            }
        } else {
            return leadingSpaces + '#'.repeat(level) + ' ' + trimmed;
        }
    }

    // ---------- 内置 Markdown 解析引擎 ----------
    const MarkdownParser = {
        parse(md) {
            let html = md;
            html = this.parseCodeBlocks(html);
            // 允许内联 HTML（颜色样式生效）
            // html = this.escapeHtml(html);
            html = html.replace(/^######\s+(.+)$/gm, '<h6>$1</h6>');
            html = html.replace(/^#####\s+(.+)$/gm, '<h5>$1</h5>');
            html = html.replace(/^####\s+(.+)$/gm, '<h4>$1</h4>');
            html = html.replace(/^###\s+(.+)$/gm, '<h3>$1</h3>');
            html = html.replace(/^##\s+(.+)$/gm, '<h2>$1</h2>');
            html = html.replace(/^#\s+(.+)$/gm, '<h1>$1</h1>');
            html = html.replace(/^(-{3,}|_{3,}|\*{3,})$/gm, '<hr>');
            html = html.replace(/!\[([^\]]*)\]\(([^)]+)\)/g, '<img src="$2" alt="$1">');
            html = html.replace(/\[([^\]]+)\]\(([^)]+)\)/g, '<a href="$2" target="_blank">$1</a>');
            html = html.replace(/\*\*\*(.+?)\*\*\*/g, '<strong><em>$1</em></strong>');
            html = html.replace(/\*\*(.+?)\*\*/g, '<strong>$1</strong>');
            html = html.replace(/\*(.+?)\*/g, '<em>$1</em>');
            html = html.replace(/~~(.+?)~~/g, '<del>$1</del>');
            html = html.replace(/`([^`]+)`/g, '<code>$1</code>');
            html = this.parseBlockquotes(html);
            html = this.parseLists(html);
            html = this.parseTables(html);
            html = this.restoreCodeBlocks(html);
            html = this.cleanupHtmlArtifacts(html);
            html = this.wrapParagraphs(html);
            return html;
        },
        escapeHtml(text) {
            return text.replace(/&/g, '&').replace(/</g, '<').replace(/>/g, '>');
        },
        codeBlocks: [],
        parseCodeBlocks(text) {
            this.codeBlocks = [];
            return text.replace(/```(\w*)\n([\s\S]*?)```/g, (match, lang, code) => {
                const index = this.codeBlocks.push({ lang, code: code.trim() }) - 1;
                return `CODEBLOCKPLACEHOLDER${index}BLOCK`;
            });
        },
        restoreCodeBlocks(text) {
            return text.replace(/CODEBLOCKPLACEHOLDER(\d+)BLOCK/g, (match, index) => {
                const block = this.codeBlocks[index];
                const escapedCode = block.code.replace(/&/g, '&').replace(/</g, '<').replace(/>/g, '>');
                return `<pre><code class="language-${block.lang}">${this.highlight(escapedCode, block.lang)}</code></pre>`;
            });
        },
        highlight(code, lang) {
            const keywords = {
                js: ['const', 'let', 'var', 'function', 'return', 'if', 'else', 'import', 'export'],
                python: ['def', 'class', 'return', 'if', 'else', 'import', 'from', 'as', 'True', 'False'],
                default: []
            };
            const kwList = keywords[lang] || keywords.default;
            const placeholderStore = [];
            const stash = (text) => `HIGHLIGHTPLACEHOLDER${placeholderStore.push(text) - 1}TOKEN`;
            let res = code;
            res = res.replace(/(["'`])(?:(?!\1)[^\\]|\\.)*?\1/g, match => stash(`<span class="md-hl-str">${match}</span>`));
            res = res.replace(/(\/\/.*$|#.*$)/gm, match => stash(`<span class="md-hl-cmt">${match}</span>`));
            res = res.replace(/\b(\d+\.?\d*)\b/g, '<span class="md-hl-num">$1</span>');
            kwList.forEach(k => {
                res = res.replace(new RegExp(`\\b(${k})\\b`, 'g'), '<span class="md-hl-kw">$1</span>');
            });
            res = res.replace(/HIGHLIGHTPLACEHOLDER(\d+)TOKEN/g, (match, index) => placeholderStore[Number(index)] || '');
            return res;
        },
        parseBlockquotes(text) {
            const lines = text.split('\n');
            let html = [];
            let inQuote = false;
            lines.forEach(line => {
                if (line.startsWith('> ') || line.startsWith('> ')) {
                    if (!inQuote) { html.push('<blockquote>'); inQuote = true; }
                    html.push(line.replace(/^(?:>|>)\s*/, ''));
                } else {
                    if (inQuote) { html.push('</blockquote>'); inQuote = false; }
                    html.push(line);
                }
            });
            if (inQuote) html.push('</blockquote>');
            return html.join('\n');
        },
        parseLists(text) {
            const lines = text.split('\n');
            let html = [];
            let listType = null;
            lines.forEach(line => {
                const ulMatch = line.match(/^[\s]*[-*+]\s+(.+)/);
                const olMatch = line.match(/^[\s]*\d+\.\s+(.+)/);
                if (ulMatch) {
                    if (listType !== 'ul') { if (listType) html.push(`</${listType}>`); html.push('<ul>'); listType = 'ul'; }
                    html.push(`<li>${ulMatch[1]}</li>`);
                } else if (olMatch) {
                    if (listType !== 'ol') { if (listType) html.push(`</${listType}>`); html.push('<ol>'); listType = 'ol'; }
                    html.push(`<li>${olMatch[1]}</li>`);
                } else {
                    if (listType) { html.push(`</${listType}>`); listType = null; }
                    html.push(line);
                }
            });
            if (listType) html.push(`</${listType}>`);
            return html.join('\n');
        },
        parseTables(text) {
            return text.replace(/^(\|.+\|)\s*\n\|[-:\s|]+\|\s*\n((?:\|.+\|\s*\n?)+)/gm, (m, h, b) => {
                const headerCells = h.split('|').slice(1, -1).map(s => `<th>${s.trim()}</th>`).join('');
                const bodyRows = b.trim().split('\n').map(r => {
                    const rowCells = r.split('|').slice(1, -1).map(c => `<td>${c.trim()}</td>`).join('');
                    return `<tr>${rowCells}</tr>`;
                }).join('');
                return `<table><thead><tr>${headerCells}</tr></thead><tbody>${bodyRows}</tbody></table>`;
            });
        },
        wrapParagraphs(text) {
            const blocks = text.split(/\n\n+/);
            return blocks.map(block => {
                block = block.trim();
                if (!block) return '';
                if (/^<(h[1-6]|ul|ol|pre|blockquote|table|hr|div|p)\b/i.test(block)) {
                    return block;
                }
                const inner = block.replace(/\n/g, '<br>');
                return `<p>${inner}</p>`;
            }).join('\n');
        },
        cleanupHtmlArtifacts(html) {
            return html
                .replace(/<(\/)?span class="(md-hl-(?:num|str|kw|cmt))">/g, '<$1span class="$2">')
                .replace(/<(\/)?(strong|em|del|code|blockquote|pre|h[1-6]|ul|ol|li|table|thead|tbody|tr|th|td|p|a|img|hr|div)([^&]*)>/g, '<$1$2$3>')
                .replace(/<br>/g, '<br>')
                .replace(/<\/span>/g, '</span>')
                .replace(/<\/a>/g, '</a>')
                .replace(/<\/code>/g, '</code>')
                .replace(/<\/strong>/g, '</strong>')
                .replace(/<\/em>/g, '</em>')
                .replace(/<\/del>/g, '</del>')
                .replace(/"/g, '"');
        }
    };

    // ---------- 启动 ----------
    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', init);
    } else {
        init();
    }
})();