// ==UserScript==
// @name         音量控制器
// @namespace    http://tampermonkey.net/
// @version      5.2
// @description  悬浮按钮可拖动，点击显示/隐藏音量面板；支持0-600%非线性调节
// @author       ukatoilol@gmail.com
// @match        *://*/*
// @run-at       document-start
// @grant        GM_setValue
// @grant        GM_getValue
// @license      MIT
// @downloadURL none
// ==/UserScript==

(function() {
    'use strict';

    // ===== 用户配置 =====
    const MAX_GAIN = 6.0; // 最大增益倍数（600%）
    const DEFAULT_VOL = 1.0; // 默认音量（100%）
    const CHECK_INTERVAL = 10000; // 定期重试连接失败的媒体（毫秒）
    const BUTTON_ID = 'volume-controller-btn';
    const PANEL_ID = 'volume-controller-panel';
    // ===================

    let audioContext = null;
    let mediaMap = new WeakMap();
    let btn = null; // 悬浮按钮元素
    let panel = null; // 音量面板元素
    let isPanelVisible = false; // 当前面板显示状态（仅记录，实际由按钮切换）

    //使用完整路径 (可优化: 单页应用（SPA）中的 URL 变化)
    const storageKey = `volume_${window.location.hostname}${window.location.pathname}`;

    // 保存音量增益值
    function saveVolumeGain(gain) {
        GM_setValue(storageKey, gain);
    }

    // 读取保存的音量增益值，若不存在则返回 DEFAULT_VOL
    function getSavedVolumeGain() {
        let saved = DEFAULT_VOL;
        try {
            saved = GM_getValue(storageKey, DEFAULT_VOL);
        } catch (e) {
            console.warn('GM_getValue 不可用，使用默认音量');
        }
        return Math.min(MAX_GAIN, Math.max(0, saved));
    }

    // ---------- 转换函数：滑块位置 (0~1) <-> 增益值 (0~MAX_GAIN) ----------
    function sliderToGain(x) {
        if (x <= 0.6) {
            // 线性映射：0 -> 0, 0.6 -> 2.0
            return x * (2.0 / 0.6); // 等价于 x * (10/3)
        } else {
            // 线性映射：0.6 -> 2.0, 1 -> 6.0
            return 10 * x - 4; // 由 2 + (x-0.6)*( (6-2)/(1-0.6) ) 推导得出
        }
    }

    function gainToSlider(gain) {
        if (gain <= 2.0) {
            // 增益 0~2.0 对应滑块 0~0.6
            return gain * (0.6 / 2.0); // 等价于 gain * 0.3
        } else {
            // 增益 2.0~6.0 对应滑块 0.6~1
            return (gain + 4) / 10;
        }
    }

    // 确保所有媒体元素都已连接（尝试连接未连接或失败的）
    function ensureAllMediaConnected() {
        document.querySelectorAll('audio, video').forEach(media => {
            const info = mediaMap.get(media);
            if (!info || info.status === 'failed') {
                connectMedia(media);
            }
        });
        // 额外同步一次保存的音量，确保所有媒体都得到应用
        const savedGain = getSavedVolumeGain();
        setVolume(savedGain);
    }

    // 强制重新连接所有媒体（清空现有映射，重新连接）
    function reconnectAllMedia() {
        mediaMap = new WeakMap(); // 清空映射，旧节点会被垃圾回收
        document.querySelectorAll('audio, video').forEach(media => connectMedia(media));
    }

    // ---------- 核心：连接单个媒体元素 ----------
    function connectMedia(media) {
        if (mediaMap.has(media)) return;
        if (media.readyState < 1) {
            media.addEventListener('loadedmetadata', () => connectMedia(media), { once: true });
            return;
        }
        try {
            if (!audioContext) {
                audioContext = new (window.AudioContext || window.webkitAudioContext)();
                document.addEventListener('visibilitychange', () => {
                    if (document.hidden) {
                        // 页面隐藏：挂起 AudioContext（如果正在运行）
                        // if (audioContext && audioContext.state === 'running') {
                        //    audioContext.suspend();
                        // }
                    } else {
                        // 页面重新可见
                        if (audioContext) {
                            if (audioContext.state === 'suspended') {
                                // 尝试恢复
                                audioContext.resume()
                                    .then(() => {
                                    console.log('✅ AudioContext resumed');
                                    // 恢复后确保所有媒体连接正常
                                    ensureAllMediaConnected();
                                })
                                    .catch(err => {
                                    console.warn('⚠️ AudioContext resume failed, attempting to reconnect', err);
                                    // 如果恢复失败，尝试重建
                                    reconnectAllMedia();
                                });
                            } else if (audioContext.state === 'closed') {
                                // Context 被意外关闭，重建
                                console.warn('AudioContext closed, recreating');
                                audioContext = null;
                                reconnectAllMedia();
                            } else {
                                // 已经是 running，但为确保安全，仍检查连接
                                ensureAllMediaConnected();
                            }
                        } else {
                            // 没有 AudioContext，创建并连接
                            reconnectAllMedia();
                        }
                    }
                });
            }
            const track = audioContext.createMediaElementSource(media);
            const gainNode = audioContext.createGain();
            // 获取保存的音量，并应用到 gainNode
            const savedGain = getSavedVolumeGain();
            gainNode.gain.value = savedGain;
            // gainNode.gain.value = DEFAULT_VOL;
            track.connect(gainNode);
            gainNode.connect(audioContext.destination);
            mediaMap.set(media, { status: 'connected', gainNode });
            console.log('✅ 音量放大器: 成功连接', media);
            if (audioContext.state === 'suspended') audioContext.resume().catch(() => {});
        } catch (err) {
            console.warn('⚠️ 音量放大器: 连接失败，降级为volume控制', err);
            mediaMap.set(media, { status: 'failed' });
            // 应用保存的音量到 volume 属性（限制在 0~1）
            const savedGain = getSavedVolumeGain();
            media.volume = Math.min(1, Math.max(0, savedGain));
        }
    }

    // ---------- 设置所有媒体的音量（接收增益值 gain）----------
    function setVolume(gain) {
        const volForVolumeProp = Math.min(1, Math.max(0, gain));
        document.querySelectorAll('audio, video').forEach(media => {
            const info = mediaMap.get(media);
            if (info && info.status === 'connected' && info.gainNode) {
                try {
                    info.gainNode.gain.value = gain;
                } catch (e) {
                    console.warn('增益节点失效，尝试重新连接', media);
                    mediaMap.delete(media);
                    connectMedia(media);
                }
            }
            media.volume = volForVolumeProp;
            if (!info) connectMedia(media);
        });
    }

    // ---------- 创建悬浮按钮 ----------
    function createButton() {
        if (btn) return;
        btn = document.createElement('div');
        btn.id = BUTTON_ID;
        btn.innerHTML = '🔊'; // 音量图标
        btn.style.cssText = `
            position: fixed;
            width: 20px;
            height: 20px;
            background: #ffffff;
            color: blue;
            border-radius: 50%;
            box-shadow: 0 2px 10px rgba(0,0,0,0.3);
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 16px;
            cursor: pointer;
            z-index: 100000;
            user-select: none;
            transition: background 0.2s, transform 0.1s;
        `;
        btn.addEventListener('mouseenter', () => btn.style.background = '#ffffff');
        btn.addEventListener('mouseleave', () => btn.style.background = '#ffffff');

        // 加载保存的位置
        const savedX = GM_getValue('btnX', 10);
        const savedY = GM_getValue('btnY', 10);
        btn.style.left = savedX + 'px';
        btn.style.top = savedY + 'px';

        document.body.appendChild(btn);
        makeDraggable(btn);
    }

    // ---------- 将面板定位在按钮附近 ----------
    function positionPanelNearButton() {
        if (!btn || !panel) return;

        const btnRect = btn.getBoundingClientRect();
        const panelWidth = panel.offsetWidth;
        const panelHeight = panel.offsetHeight;
        const viewportWidth = window.innerWidth;
        const viewportHeight = window.innerHeight;

        // 默认位置：按钮正下方，左边缘与按钮对齐
        let top = btnRect.bottom + 5;
        let left = btnRect.left;

        // 如果下方空间不足，放在按钮上方
        if (top + panelHeight > viewportHeight) {
            top = btnRect.top - panelHeight - 5;
        }

        // 如果上方也不足，则强制放在底部（但这种情况极少）
        if (top < 0) {
            top = Math.max(5, viewportHeight - panelHeight - 5);
        }

        // 水平边界检查：防止右侧溢出
        if (left + panelWidth > viewportWidth) {
            left = viewportWidth - panelWidth - 5;
        }
        // 防止左侧溢出
        if (left < 0) {
            left = 5;
        }

        panel.style.top = top + 'px';
        panel.style.left = left + 'px';
    }


    // ---------- 使元素可拖动 ----------
    function makeDraggable(el) {
        let offsetX, offsetY, isDragging = false, startX, startY;
        const dragThreshold = 5; // 拖动阈值（像素）

        el.addEventListener('mousedown', (e) => {
            e.preventDefault();
            startX = e.clientX;
            startY = e.clientY;
            isDragging = false; // 尚未开始拖动

            const rect = el.getBoundingClientRect();
            offsetX = e.clientX - rect.left;
            offsetY = e.clientY - rect.top;

            const onMouseMove = (e) => {
                e.preventDefault();
                const dx = e.clientX - startX;
                const dy = e.clientY - startY;
                if (!isDragging && (Math.abs(dx) > dragThreshold || Math.abs(dy) > dragThreshold)) {
                    isDragging = true;
                }
                if (isDragging) {
                    let newLeft = e.clientX - offsetX;
                    let newTop = e.clientY - offsetY;
                    newLeft = Math.max(0, Math.min(window.innerWidth - el.offsetWidth, newLeft));
                    newTop = Math.max(0, Math.min(window.innerHeight - el.offsetHeight, newTop));
                    el.style.left = newLeft + 'px';
                    el.style.top = newTop + 'px';

                    // 如果面板当前可见，同步移动面板
                    if (panel && panel.style.display === 'block') {
                        positionPanelNearButton();
                    }
                }
            };

            const onMouseUp = (e) => {
                document.removeEventListener('mousemove', onMouseMove);
                document.removeEventListener('mouseup', onMouseUp);
                document.body.style.userSelect = ''; // 恢复文本选择
                if (!isDragging) {
                    // 没有拖动，视为点击
                    togglePanel();
                } else {
                    // 拖动结束，保存位置
                    GM_setValue('btnX', parseInt(el.style.left));
                    GM_setValue('btnY', parseInt(el.style.top));
                }
            };

            document.addEventListener('mousemove', onMouseMove);
            document.addEventListener('mouseup', onMouseUp);
            document.body.style.userSelect = 'none'; // 防止拖动时选中文本
        });
    }

    // ---------- 创建音量面板 ----------
    function createPanel() {
        if (panel) return;
        panel = document.createElement('div');
        panel.id = PANEL_ID;
        // const initialSliderPos = gainToSlider(DEFAULT_VOL);
        const savedGain = getSavedVolumeGain(); // 读取保存的音量
        const initialSliderPos = gainToSlider(savedGain); // 计算滑块位置
        panel.innerHTML = `
            <div style="margin-bottom:5px; font-weight:bold;">全局音量 (0-600%，非线性)</div>
            <input type="range" id="global-gain-slider" min="0" max="1" step="0.001" value="${initialSliderPos}" style="cursor:grab;">
            <span id="global-gain-display">${Math.round(savedGain * 100)}%</span>
        `;
        panel.style.cssText = `
            cursor:default;
            position: fixed;
            top: 60px;      /* 默认在按钮下方，可通过拖动改变位置？如果需要可添加独立拖动 */
            left: 10px;
            background: white;
            padding: 10px;
            border: 1px solid #ccc;
            border-radius: 5px;
            box-shadow: 0 2px 10px rgba(0,0,0,0.2);
            z-index: 100000;
            font-family: sans-serif;
            display: none;  /* 默认隐藏 */
        `;
        document.body.appendChild(panel);
        // 在 panel 创建并插入到 document.body 之后，添加点击事件
        panel.addEventListener('click', (e) => {
            // 如果点击的是滑块（<input type="range">），不处理，让滑块正常工作
            if (e.target.tagName === 'INPUT' && e.target.type === 'range') {
                return; // 注意：这里不需要阻止冒泡，因为滑块本身不触发隐藏即可
            }
            // 否则隐藏面板
            panel.style.display = 'none';
            isPanelVisible = false; // 更新状态变量
            e.stopPropagation(); // 阻止事件冒泡到按钮，避免按钮的切换逻辑干扰
        });

        const slider = document.getElementById('global-gain-slider');
        const display = document.getElementById('global-gain-display');
        slider.addEventListener('input', (e) => {
            const x = parseFloat(e.target.value);
            const gain = sliderToGain(x);
            display.textContent = Math.round(gain * 100) + '%';
            setVolume(gain);
            saveVolumeGain(gain); // 新增：保存音量
        });
        slider.addEventListener('mousedown', (e) => {
            if (audioContext && audioContext.state === 'suspended') {
                audioContext.resume().catch(() => {});
            }
        });
        // 在滑块绑定后添加：
        setVolume(savedGain);
    }

    // ---------- 切换面板显示/隐藏 ----------
    function togglePanel() {
        if (!panel) return;
        isPanelVisible = !isPanelVisible;
        panel.style.display = isPanelVisible ? 'block' : 'none';
        if (isPanelVisible) {
            positionPanelNearButton(); // 显示时定位
        }
    }

    // ---------- 更新UI的显示状态（根据有无媒体）----------
    function updateUIVisibility() {
        const hasMedia = document.querySelectorAll('audio, video').length > 0;
        if (hasMedia) {
            if (!btn) createButton();
            if (!panel) createPanel();
            // 按钮始终显示
            btn.style.display = 'flex';
            // 面板的显示由按钮控制，但若媒体消失，我们强制隐藏面板
            if (!hasMedia) {
                panel.style.display = 'none';
                isPanelVisible = false;
            }
        } else {
            if (btn) btn.style.display = 'none';
            if (panel) {
                panel.style.display = 'none';
                isPanelVisible = false;
            }
        }
    }

    // ---------- 监听媒体元素的增减 ----------
    const observer = new MutationObserver(() => {
        document.querySelectorAll('audio, video').forEach(media => {
            if (!mediaMap.has(media)) connectMedia(media);
        });
        updateUIVisibility();
    });

    // 初始化
    if (document.body) {
        observer.observe(document.body, { childList: true, subtree: true });
        document.querySelectorAll('audio, video').forEach(media => connectMedia(media));
        updateUIVisibility();
    } else {
        window.addEventListener('DOMContentLoaded', () => {
            observer.observe(document.body, { childList: true, subtree: true });
            document.querySelectorAll('audio, video').forEach(media => connectMedia(media));
            updateUIVisibility();
        });
    }

    // 定期重试连接失败的媒体
    setInterval(() => {
        document.querySelectorAll('audio, video').forEach(media => {
            const info = mediaMap.get(media);
            if (!info || info.status === 'failed') connectMedia(media);
        });
        updateUIVisibility();
    }, CHECK_INTERVAL);

    //
    window.addEventListener('resize', () => {
        if (panel && panel.style.display === 'block') {
            positionPanelNearButton();
        }
    });

    // 清理
    window.addEventListener('beforeunload', () => {
        observer.disconnect();
        if (audioContext) audioContext.close();
    });
})();