// ==UserScript==
// @name         哔哩哔哩视频倍速扩展 3x/4x
// @tag          哔哩哔哩 bilibili B站
// @namespace    https://github.com/
// @version      3.5.0
// @description  为哔哩哔哩原生倍速菜单添加3倍速和4倍速档位；无定时器，几乎零开销。
// @author       deran
// @match        *://www.bilibili.com/video/*
// @match        *://www.bilibili.com/bangumi/play/*
// @match        *://www.bilibili.com/list/watchlater*
// @grant        none
// @run-at       document-end
// @license      MIT
// ==/UserScript==

(function() {
    'use strict';

    /********** 配置项 **********/
    const EXTRA_SPEEDS = [3, 4];
    const VIDEO_SELECTOR = 'video';
    const MENU_SELECTORS = [
        '.bpx-player-ctrl-playbackrate-menu',
        '.bpx-player-ctrl-speed-menu'
    ];
    const SPEED_BTN_SELECTOR = '.bpx-player-ctrl-playbackrate';

    /********** DOM工具 **********/
    function waitForElement(selector, parent = document.body) {
        return new Promise(resolve => {
            const target = parent.querySelector(selector);
            if (target) return resolve(target);

            const observer = new MutationObserver(() => {
                const target = parent.querySelector(selector);
                if (target) {
                    observer.disconnect();
                    resolve(target);
                }
            });
            observer.observe(parent, { childList: true, subtree: true });
        });
    }

    function getMenuEl() {
        for (const sel of MENU_SELECTORS) {
            const el = document.querySelector(sel);
            if (el?.children.length) return el;
        }
        return null;
    }

    /********** 菜单注入 **********/
    function injectMenuOptions() {
        const menu = getMenuEl();
        if (!menu || menu.dataset.customInjected) return;

        // 收集原生已有倍速，自动去重
        const existing = new Set();
        const items = menu.querySelectorAll('li, .bpx-player-ctrl-playbackrate-menu-item');
        items.forEach(item => {
            const v = parseFloat(item.dataset.value);
            if (!isNaN(v)) existing.add(v);
        });

        // 过滤并排序新增档位
        const speeds = EXTRA_SPEEDS.filter(r => !existing.has(r)).sort((a, b) => b - a);
        if (speeds.length === 0) {
            menu.dataset.customInjected = 'true';
            return;
        }

        // 批量注入选项
        const frag = document.createDocumentFragment();
        speeds.forEach(rate => {
            const li = document.createElement('li');
            if (items[0]) li.className = items[0].className;
            li.dataset.value = rate;
            li.textContent = `${rate}.0x`;

            li.addEventListener('click', () => {
                const video = document.querySelector(VIDEO_SELECTOR);
                if (video) video.playbackRate = rate;
            });
            frag.appendChild(li);
        });

        menu.insertBefore(frag, menu.firstChild);
        menu.dataset.customInjected = 'true';
    }

    /********** SPA路由适配 **********/
    function onRouteChange() {
        setTimeout(injectMenuOptions, 0);
    }

    const _push = history.pushState;
    history.pushState = function(...args) {
        _push.apply(this, args);
        onRouteChange();
    };
    const _replace = history.replaceState;
    history.replaceState = function(...args) {
        _replace.apply(this, args);
        onRouteChange();
    };
    window.addEventListener('popstate', onRouteChange);

    // 菜单懒加载兼容：鼠标悬停倍速按钮时检查注入
    async function initHoverFallback() {
        const btn = await waitForElement(SPEED_BTN_SELECTOR);
        if (!btn || btn.dataset.fallbackBound) return;
        btn.dataset.fallbackBound = 'true';
        btn.addEventListener('mouseenter', injectMenuOptions);
    }

    /********** 初始化 **********/
    initHoverFallback();
    injectMenuOptions();
})();