// ==UserScript==
// @name         LeetCode CN 题目提取
// @namespace    http://tampermonkey.net/
// @version      7.8
// @description  结构化提取 LeetCode 题目，高级玻璃态 UI，稳定剪贴板，适配 SPA
// @author       GitHub Copilot
// @match        https://leetcode.cn/problems/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    // ==========================================
    // 1. UI 样式注入 (Glassmorphism & Animations)
    // ==========================================
    const injectStyles = () => {
        if (document.getElementById('lc-glass-styles')) return;
        const style = document.createElement('style');
        style.id = 'lc-glass-styles';
        style.innerHTML = `
            /* 悬浮按钮 - 毛玻璃效果 */
            #lc-glass-copy-btn {
                position: fixed;
                bottom: 40px;
                right: 40px;
                z-index: 999999;
                padding: 14px 24px;
                font-size: 15px;
                font-weight: 500;
                color: #ffffff;
                background: rgba(30, 30, 30, 0.65);
                backdrop-filter: blur(12px);
                -webkit-backdrop-filter: blur(12px);
                border: 1px solid rgba(255, 255, 255, 0.15);
                border-radius: 20px;
                box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.3), inset 0 0 0 1px rgba(255,255,255,0.05);
                cursor: pointer;
                transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
                display: flex;
                align-items: center;
                gap: 8px;
                animation: slideFadeUp 0.6s ease-out forwards;
                user-select: none;
            }

            /* 浅色模式适配 */
            @media (prefers-color-scheme: light) {
                #lc-glass-copy-btn {
                    background: rgba(255, 255, 255, 0.7);
                    color: #333333;
                    border: 1px solid rgba(255, 255, 255, 0.6);
                    box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.1), inset 0 0 0 1px rgba(255,255,255,0.4);
                }
            }

            #lc-glass-copy-btn:hover {
                transform: translateY(-4px) scale(1.02);
                box-shadow: 0 12px 40px rgba(0, 0, 0, 0.4), inset 0 0 0 1px rgba(255,255,255,0.2);
                background: rgba(45, 45, 45, 0.75);
            }

            @media (prefers-color-scheme: light) {
                #lc-glass-copy-btn:hover {
                    background: rgba(255, 255, 255, 0.9);
                    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.15), inset 0 0 0 1px rgba(255,255,255,0.8);
                }
            }

            #lc-glass-copy-btn:active {
                transform: translateY(2px) scale(0.98);
                transition: all 0.1s;
            }

            /* Toast 提示框 */
            .lc-glass-toast {
                position: fixed;
                bottom: 100px;
                right: 40px;
                z-index: 999999;
                padding: 12px 24px;
                font-size: 14px;
                color: #ffffff;
                background: rgba(40, 167, 69, 0.8);
                backdrop-filter: blur(10px);
                border: 1px solid rgba(255, 255, 255, 0.2);
                border-radius: 12px;
                box-shadow: 0 8px 24px rgba(0,0,0,0.2);
                opacity: 0;
                transform: translateY(20px);
                transition: all 0.4s cubic-bezier(0.68, -0.55, 0.265, 1.55);
                pointer-events: none;
            }
            .lc-glass-toast.show {
                opacity: 1;
                transform: translateY(0);
            }
            .lc-glass-toast.error {
                background: rgba(220, 53, 69, 0.8);
            }

            /* 初始进场动画 */
            @keyframes slideFadeUp {
                0% { opacity: 0; transform: translateY(30px); }
                100% { opacity: 1; transform: translateY(0); }
            }
        `;
        document.head.appendChild(style);
    };

    // ==========================================
    // 2. 剪贴板双重降级写入 + 日志
    // ==========================================
    const copyToClipboard = async (text) => {
        console.log('copy start');
        try {
            // Priority 1: 现代 Clipboard API
            await navigator.clipboard.writeText(text);
            console.log('clipboard api success');
            return true;
        } catch (err) {
            console.log('clipboard api failed', err);
            
            // Priority 2: 传统 fallback
            try {
                const textarea = document.createElement('textarea');
                textarea.value = text;
                // 隐藏元素，防止页面跳动
                textarea.style.position = 'fixed';
                textarea.style.top = '-9999px';
                textarea.style.left = '-9999px';
                textarea.style.opacity = '0';
                document.body.appendChild(textarea);
                
                textarea.select();
                const success = document.execCommand('copy');
                document.body.removeChild(textarea);
                
                if (success) {
                    console.log('execCommand copy success');
                    return true;
                } else {
                    console.log('execCommand copy failed');
                    return false;
                }
            } catch (fallbackErr) {
                console.log('execCommand copy failed', fallbackErr);
                return false;
            }
        }
    };

    // ==========================================
    // 3. 内容提纯与重组
    // ==========================================
    const extractTitle = () => {
        // 通常 document.title 的格式为 "1. 两数之和 - 力扣..."
        let titleBlock = document.title.split('-')[0].trim();
        // 如果未加载完成可能只拿到 "力扣"，做个检查
        if (titleBlock && titleBlock !== "力扣" && titleBlock !== "LeetCode") {
            return titleBlock;
        }
        
        // 备用选择器
        const titleEl = document.querySelector('h1 a, .text-title-large a, [data-cypress="QuestionTitle"]');
        return titleEl ? titleEl.innerText.trim() : "未知题目";
    };

    const extractDifficulty = () => {
        // 利用专属类名探测
        const diffEls = document.querySelectorAll('[class*="text-difficulty-"]');
        if (diffEls.length > 0) return diffEls[0].innerText.trim();
        
        // 备用：暴力文本匹配
        const tags = Array.from(document.querySelectorAll('span, div')).slice(0, 200);
        for (let tag of tags) {
            const text = tag.innerText?.trim();
            if (['简单', '中等', '困难'].includes(text)) {
                return text;
            }
        }
        return "未知";
    };

    const extractStructuredContent = () => {
        const container = document.querySelector('[data-track-load="description_content"]');
        if (!container) throw new Error("未找到题目正文容器 !");

        let contentLines = [];

        // 仅抓取顶层/块级元素，过滤不必要的嵌套和杂质
        const childNodes = Array.from(container.children);
        childNodes.forEach(child => {
            // 跳过可能混入的无关元素、隐藏元素、无关按钮
            const tagName = child.tagName.toLowerCase();
            const text = child.innerText?.trim();
            
            if (!text) return;
            // 重点提取这些标签类型
            if (['p', 'pre', 'ul', 'ol', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'blockquote'].includes(tagName)) {
                contentLines.push(text);
            }
        });

        const rawContent = contentLines.join('\n\n');
        
        // 清洗：把连续超过3个的换行压缩为2个换行，去除首尾空白
        let cleanedContent = rawContent.replace(/\n{3,}/g, '\n\n').trim();

        // 拼接成标准格式
        return `题目：${extractTitle()}\n难度：${extractDifficulty()}\n\n题目描述：\n${cleanedContent}`;
    };

    // ==========================================
    // 4. UI 提示反馈 
    // ==========================================
    const showToast = (message, isError = false) => {
        let toast = document.getElementById('lc-glass-toast');
        if (!toast) {
            toast = document.createElement('div');
            toast.id = 'lc-glass-toast';
            document.body.appendChild(toast);
        }
        
        toast.className = `lc-glass-toast ${isError ? 'error' : ''}`;
        toast.innerText = message;
        
        // 触发重绘以呈现动画
        void toast.offsetWidth; 
        toast.classList.add('show');

        // 3秒后隐藏
        setTimeout(() => toast.classList.remove('show'), 3000);
    };

    // ==========================================
    // 5. 主点击事件处理
    // ==========================================
    const handleCopyAction = async () => {
        const btn = document.getElementById('lc-glass-copy-btn');
        if (!btn) return;
        
        const originalText = btn.innerHTML;
        btn.innerHTML = '⏳ 提取中...';
        btn.style.pointerEvents = 'none';

        try {
            const formattedText = extractStructuredContent();
            const success = await copyToClipboard(formattedText);

            if (success) {
                btn.innerHTML = '✅ 复制成功';
                showToast('已复制到系统剪贴板！');
            } else {
                throw new Error("写入剪贴板API全量失败");
            }
        } catch (error) {
            console.error(error);
            btn.innerHTML = '❌ 提取失败';
            showToast('复制失败：' + error.message, true);
        } finally {
            // 2 秒后恢复按键状态
            setTimeout(() => {
                const currentBtn = document.getElementById('lc-glass-copy-btn');
                if (currentBtn) {
                    currentBtn.innerHTML = '📋 复制题目';
                    currentBtn.style.pointerEvents = 'auto';
                }
            }, 2000);
        }
    };

    // ==========================================
    // 6. 挂载与 SPA 监听
    // ==========================================
    const mountButton = () => {
        // 防止重复挂载
        if (document.getElementById('lc-glass-copy-btn')) return;

        injectStyles();

        const btn = document.createElement('div');
        btn.id = 'lc-glass-copy-btn';
        btn.innerHTML = '📋 复制题目';
        btn.addEventListener('click', handleCopyAction);
        
        document.body.appendChild(btn);
    };

    // 初始化 SPA 路由防撕裂挂载
    const initSPAObserver = () => {
        let lastUrl = window.location.href;

        // 首屏挂载
        setTimeout(mountButton, 1000); 

        // 监听由于 Vue/React 导致的 DOM 变化与路由更新
        const observer = new MutationObserver(() => {
            const currentUrl = window.location.href;
            if (currentUrl !== lastUrl) {
                lastUrl = currentUrl;
                
                // 页面切换，清理旧的元素重新挂载
                const oldBtn = document.getElementById('lc-glass-copy-btn');
                if (oldBtn) oldBtn.remove();
                
                setTimeout(mountButton, 1500); // 给新内容一定的渲染时间
            } else if (!document.getElementById('lc-glass-copy-btn')) {
                // 如果在同一页面被外部脚本意外删除了，补发注入
                mountButton();
            }
        });

        observer.observe(document.body, { childList: true, subtree: true });
    };

    // 启动脚本
    initSPAObserver();
})();