// ==UserScript==
// @name         搜索引擎切换器 / Search Engine Switcher
// @namespace    http://tampermonkey.net/
// @version      0.7.1
// @description  一键切换多个搜索引擎！支持Google、Bing、百度、360搜索等主流平台。可拖拽、记忆位置，支持选中文本搜索。性能优化版本。
// @author       AI优化版-原作者：WUJI
// @match        *://www.google.com*/search*
// @match        *://www.bing.com/search*
// @match        *://cn.bing.com/search*
// @match        *://*yandex.com/search*
// @match        *://www.baidu.com/s*
// @match        *://www.baidu.com/baidu*
// @match        *://www.sogou.com/web*
// @match        *://search.bilibili.com/all*
// @match        *://www.zhihu.com/search*
// @match        *://www.so.com/s*
// @grant        none
// @run-at       document-body
// @license      MIT
// @icon        data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><text y=".9em" font-size="80">🔎</text></svg>
// ==/UserScript==

(function() {
    'use strict';

    // ==================== 配置项 ====================
    const CONFIG = {
        ICON_SIZE: '32px',
        LIST_MAX_WIDTH: '160px',
        FONT_SIZE: '14px',
        STORAGE_KEY: 'searchSwitcherPos',
        HALF_HIDE_TRANSLATE: '-16px',
        // 性能优化：防抖延迟
        DEBOUNCE_DELAY: 100,
        // 拖拽阈值（像素），超过才认为是拖动，避免误触
        DRAG_THRESHOLD: 5,
        // 启用硬件加速
        ENABLE_HW_ACCELERATION: true
    };

    // ==================== 搜索引擎定义 ====================
    const SEARCH_ENGINES = [
        { name: "Bing", url: "https://www.bing.com/search?q=", keyName: "q", testUrl: /https:\/\/(www|cn)\.bing\.com\/search.*/ },
        { name: "百度", url: "https://www.baidu.com/s?wd=", keyName: "wd", testUrl: /https:\/\/www\.baidu\.com\/(s|baidu).*/ },
        { name: "Yandex", url: "https://yandex.com/search?text=", keyName: "text", testUrl: /https:\/\/yandex\.com\/search.*/ },
        { name: "360搜索", url: "https://www.so.com/s?q=", keyName: "q", testUrl: /https:\/\/www\.so\.com\/s.*/ },
        { name: "Google", url: "https://www.google.com/search?q=", keyName: "q", testUrl: /https:\/\/www\.google\.(com|com\.hk)\/search.*/ },
        { name: "搜狗", url: "https://www.sogou.com/web?query=", keyName: "query", testUrl: /https:\/\/www\.sogou\.com\/web.*/ },
        { name: "哔站", url: "https://search.bilibili.com/all?keyword=", keyName: "keyword", testUrl: /https:\/\/search\.bilibili\.com\/all.*/ },
        { name: "知乎", url: "https://www.zhihu.com/search?q=", keyName: "q", testUrl: /https:\/\/www\.zhihu\.com\/search.*/ }
    ];

    // ==================== 工具函数 ====================
    function getCurrentEngine() {
        const url = window.location.href;
        for (const engine of SEARCH_ENGINES) {
            if (engine.testUrl.test(url)) return engine;
        }
        return null;
    }

    function extractKeywordFromUrl(engine) {
        try {
            const url = new URL(window.location.href);
            return url.searchParams.get(engine.keyName) || '';
        } catch {
            return '';
        }
    }

    function getKeywords() {
        const currentEngine = getCurrentEngine();
        if (currentEngine) {
            const kw = extractKeywordFromUrl(currentEngine);
            if (kw) return kw;
        }
        const selected = window.getSelection().toString().trim();
        if (selected) return selected;
        return prompt('请输入搜索关键词：', '') || '';
    }

    function isDarkMode() {
        return window.matchMedia('(prefers-color-scheme: dark)').matches;
    }

    function loadPosition() {
        try {
            const pos = JSON.parse(localStorage.getItem(CONFIG.STORAGE_KEY));
            if (pos && typeof pos.left === 'number' && typeof pos.top === 'number') {
                return pos;
            }
        } catch {}
        return { left: 0, top: 100 };
    }

    function savePosition(left, top) {
        localStorage.setItem(CONFIG.STORAGE_KEY, JSON.stringify({ left, top }));
    }

    // 防抖函数
    function debounce(func, wait) {
        let timeout;
        return function executedFunction(...args) {
            const later = () => {
                clearTimeout(timeout);
                func(...args);
            };
            clearTimeout(timeout);
            timeout = setTimeout(later, wait);
        };
    }

    // ==================== 样式创建 ====================
    function createStyle() {
        const style = document.createElement('style');
        style.textContent = `
            :root {
                --list-bg-light: rgba(255, 255, 255, 0.95);
                --list-bg-dark: rgba(40, 40, 40, 0.95);
                --text-light: #333;
                --text-dark: #eee;
                --hover-light: rgba(0, 0, 0, 0.1);
                --hover-dark: rgba(255, 255, 255, 0.1);
            }
            #search-app-box {
                position: fixed;
                top: 0;
                left: 0;
                width: ${CONFIG.ICON_SIZE};
                height: ${CONFIG.ICON_SIZE};
                background: transparent !important;
                z-index: 2147483647;
                cursor: move;
                font-size: ${CONFIG.FONT_SIZE};
                transition: transform 0.3s ease-in-out, left 0.3s ease-in-out, top 0.3s ease-in-out;
                user-select: none;
                transform: translateX(${CONFIG.HALF_HIDE_TRANSLATE});
                will-change: transform;
                ${CONFIG.ENABLE_HW_ACCELERATION ? 'backface-visibility: hidden; perspective: 1px;' : ''}
            }
            #search-app-box.dragging {
                transition: none;
            }
            #search-app-box:not(.half-hidden) {
                transform: translateX(0);
            }
            #search-app-icon {
                width: 100%;
                height: 100%;
                display: flex;
                justify-content: center;
                align-items: center;
                font-size: ${CONFIG.ICON_SIZE};
                background: transparent !important;
                color: inherit;
            }
            #search-engine-list {
                position: absolute;
                top: 2%;
                left: ${CONFIG.ICON_SIZE};
                min-width: 80px;
                max-width: ${CONFIG.LIST_MAX_WIDTH};
                max-height: 70vh;
                overflow-y: auto;
                background-color: var(--list-bg-light);
                border-radius: 8px;
                box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
                opacity: 0;
                visibility: hidden;
                transform: translateX(-10px);
                transition: opacity 0.2s, visibility 0.2s, transform 0.2s;
                backdrop-filter: blur(4px);
                white-space: nowrap;
            }
            #search-engine-list a {
                display: block;
                padding: 10px 16px;
                color: var(--text-light);
                text-decoration: none;
                transition: background-color 0.2s;
                cursor: pointer;
            }
            #search-engine-list a:hover {
                background-color: var(--hover-light);
            }
            body.dark-mode #search-engine-list {
                background-color: var(--list-bg-dark);
            }
            body.dark-mode #search-engine-list a {
                color: var(--text-dark);
            }
            body.dark-mode #search-engine-list a:hover {
                background-color: var(--hover-dark);
            }

            /* 添加滚动条样式 */
            #search-engine-list::-webkit-scrollbar {
                width: 6px;
            }
            #search-engine-list::-webkit-scrollbar-track {
                background: rgba(0,0,0,0.1);
                border-radius: 3px;
            }
            #search-engine-list::-webkit-scrollbar-thumb {
                background: rgba(0,0,0,0.3);
                border-radius: 3px;
            }
            #search-engine-list::-webkit-scrollbar-thumb:hover {
                background: rgba(0,0,0,0.5);
            }
        `;
        document.head.appendChild(style);
    }

    // ==================== 创建UI ====================
    function createSearchBox() {
        const box = document.createElement('div');
        box.id = 'search-app-box';
        box.classList.add('half-hidden');

        const savedPos = loadPosition();
        box.style.left = savedPos.left + 'px';
        box.style.top = savedPos.top + 'px';

        const icon = document.createElement('div');
        icon.id = 'search-app-icon';
        icon.innerText = '🔎';
        box.appendChild(icon);

        const listContainer = document.createElement('div');
        listContainer.id = 'search-engine-list';

        const currentKeywords = getKeywords();
        const currentEngine = getCurrentEngine();

        for (const engine of SEARCH_ENGINES) {
            if (currentEngine && engine.name === currentEngine.name) continue;
            const a = document.createElement('a');
            a.href = engine.url + encodeURIComponent(currentKeywords);
            a.title = `在${engine.name}中搜索: ${currentKeywords}`;
            a.innerText = engine.name;
            a.dataset.url = a.href; // 备用
            listContainer.appendChild(a);
        }

        box.appendChild(listContainer);
        document.body.appendChild(box);

        let isDragging = false;
        let isMouseOverBox = false;
        let rafId = null;
        let startX, startY, startLeft, startTop;
        let dragDistance = 0; // 记录拖拽距离，用于判断是否为拖动操作

        // 显示图标和列表
        function showAll() {
            box.classList.remove('half-hidden');
            listContainer.style.opacity = '1';
            listContainer.style.visibility = 'visible';
            listContainer.style.transform = 'translateX(0)';
        }

        // 隐藏列表，图标半隐藏（如果条件满足）
        function hideAll() {
            if (isDragging || isMouseOverBox) return;
            box.classList.add('half-hidden');
            listContainer.style.opacity = '0';
            listContainer.style.visibility = 'hidden';
            listContainer.style.transform = 'translateX(-10px)';
        }

        // 鼠标进入
        box.addEventListener('mouseenter', () => {
            isMouseOverBox = true;
            showAll();
        });

        // 鼠标离开
        box.addEventListener('mouseleave', () => {
            isMouseOverBox = false;
            hideAll();
        });

        // 拖拽开始
        box.addEventListener('mousedown', (e) => {
            if (e.button !== 0) return;
            e.preventDefault();
            isDragging = true;
            dragDistance = 0; // 重置拖拽距离
            showAll();
            box.classList.add('dragging');

            startX = e.clientX;
            startY = e.clientY;
            startLeft = box.offsetLeft;
            startTop = box.offsetTop;

            function onMouseMove(e) {
                if (rafId) cancelAnimationFrame(rafId);
                rafId = requestAnimationFrame(() => {
                    const dx = e.clientX - startX;
                    const dy = e.clientY - startY;
                    dragDistance = Math.sqrt(dx * dx + dy * dy); // 计算拖拽距离

                    // 使用 transform 移动，避免重排
                    box.style.transform = `translate(${dx}px, ${dy}px)`;
                    rafId = null;
                });
            }

            function onMouseUp(e) {
                if (rafId) {
                    cancelAnimationFrame(rafId);
                    rafId = null;
                }
                document.removeEventListener('mousemove', onMouseMove);
                document.removeEventListener('mouseup', onMouseUp);

                // 如果拖拽距离小于阈值，则认为是点击而非拖动
                if (dragDistance < CONFIG.DRAG_THRESHOLD) {
                    isDragging = false;
                    box.classList.remove('dragging');

                    // 检查鼠标是否还在 box 内，如果是则显示列表
                    const elemAtMouse = document.elementFromPoint(e.clientX, e.clientY);
                    const mouseInBox = box.contains(elemAtMouse);
                    if (mouseInBox) {
                        isMouseOverBox = true;
                        showAll();
                    } else {
                        isMouseOverBox = false;
                        hideAll();
                    }
                    return;
                }

                // 计算最终位置并更新 left/top，清除 transform
                const finalLeft = startLeft + (parseInt(box.style.transform.match(/translate\(([-\d.]+)px/)?.[1] || 0));
                const finalTop = startTop + (parseInt(box.style.transform.match(/translate\([-\d.]+px,\s*([-\d.]+)px/)?.[1] || 0));

                // 确保元素不会被拖出屏幕边界
                const clampedLeft = Math.max(0, Math.min(finalLeft, window.innerWidth - parseInt(CONFIG.ICON_SIZE)));
                const clampedTop = Math.max(0, Math.min(finalTop, window.innerHeight - parseInt(CONFIG.ICON_SIZE)));

                box.style.left = clampedLeft + 'px';
                box.style.top = clampedTop + 'px';
                box.style.transform = ''; // 清除拖拽偏移

                isDragging = false;
                box.classList.remove('dragging');
                savePosition(clampedLeft, clampedTop);

                // 检查鼠标是否还在 box 内
                const elemAtMouse = document.elementFromPoint(e.clientX, e.clientY);
                const mouseInBox = box.contains(elemAtMouse);
                if (!mouseInBox) {
                    isMouseOverBox = false;
                    hideAll();
                } else {
                    isMouseOverBox = true;
                }
            }

            document.addEventListener('mousemove', onMouseMove);
            document.addEventListener('mouseup', onMouseUp);
        });

        // 事件委托处理列表点击
        listContainer.addEventListener('click', (e) => {
            const target = e.target.closest('a');
            if (!target) return;
            e.preventDefault();
            const url = target.href;
            if (e.ctrlKey || e.metaKey) {
                window.open(url, '_blank');
            } else {
                window.location.href = url;
            }
        });

        // 优化键盘事件监听
        document.addEventListener('keydown', (e) => {
            if (e.key === 'Escape' && !box.classList.contains('half-hidden')) {
                hideAll();
            }
        });
    }

    // ==================== 主题切换 ====================
    function updateTheme() {
        document.body.classList.toggle('dark-mode', isDarkMode());
    }

    // ==================== 初始化 ====================
    function init() {
        createStyle();
        createSearchBox();
        updateTheme();

        // 使用防抖优化主题变化监听
        const debouncedUpdateTheme = debounce(updateTheme, CONFIG.DEBOUNCE_DELAY);
        window.matchMedia('(prefers-color-scheme: dark)')
              .addEventListener('change', debouncedUpdateTheme);
    }

    // 直接初始化（@run-at document-body 保证 body 存在）
    if (document.body) {
        init();
    } else {
        // 极少数情况 fallback
        window.addEventListener('DOMContentLoaded', init);
    }
})();