// ==UserScript==
// @name         B站PCDN拦截器
// @namespace    lllbbbzzz
// @version      7.1
// @description  拦截B站PCDN视频源，主动替换为正规CDN，减少上传带宽占用
// @author       lllbbbzzz
// @match        *://*.bilibili.com/*
// @match        *://*.bilibili.tv/*
// @match        *://*.bilivideo.cn/*
// @run-at       document-start
// @grant        GM_registerMenuCommand
// @license      MIT
// ==/UserScript==

(function () {
    'use strict';

    var KEY = 'pcdn_killer_v7';
    var IND = 'pcdn-ind';
    var enabled = localStorage.getItem(KEY) !== '0';
    var count = 0;

    /* ════════ 检测 ════════ */
    function isPCDN(u) {
        return u && (/\.mcdn\.bilivideo\.cn/i.test(u) || /xy\d+x\d+x\d+x\d+xy/i.test(u));
    }

    function isSegment(u) {
        return u && (/\/seg\//i.test(u) || /\d+-\d+\.(m4s|ts)(\?|$)/i.test(u));
    }

    /* ════════ 主动替换CDN ════════ */
    function replaceCDN(json) {
        if (!enabled || !json || !json.dash) return json;

        var legitPaths = [];
        ['video', 'audio'].forEach(function (t) {
            if (!json.dash[t]) return;
            json.dash[t].forEach(function (s) {
                if (s.base_url && !isPCDN(s.base_url)) {
                    legitPaths.push(s.base_url);
                }
                if (s.backup_url) {
                    s.backup_url.forEach(function (u) {
                        if (!isPCDN(u)) legitPaths.push(u);
                    });
                }
            });
        });

        if (legitPaths.length === 0) return json;

        var legitHosts = [];
        legitPaths.forEach(function (u) {
            try {
                var h = new URL(u, location.origin).host;
                if (legitHosts.indexOf(h) === -1) legitHosts.push(h);
            } catch (_) { /* ignore */ }
        });

        if (legitHosts.length === 0) return json;

        var dirty = false;

        ['video', 'audio'].forEach(function (t) {
            if (!json.dash[t]) return;
            json.dash[t].forEach(function (s) {
                var newBackups = [];

                if (s.backup_url) {
                    s.backup_url.forEach(function (u) {
                        if (!isPCDN(u)) {
                            newBackups.push(u);
                        } else {
                            dirty = true;
                        }
                    });
                }

                if (isPCDN(s.base_url)) {
                    if (newBackups.length > 0) {
                        s.base_url = newBackups[0];
                    } else {
                        var path = s.base_url.replace(/^https?:\/\/[^/]+/, '');
                        s.base_url = 'https://' + legitHosts[0] + path;
                    }
                    dirty = true;
                }

                while (newBackups.length < 2 && legitHosts.length > 0) {
                    var host = legitHosts[newBackups.length % legitHosts.length];
                    var ref = s.base_url.replace(/^https?:\/\/[^/]+/, '');
                    newBackups.push('https://' + host + ref);
                }

                s.backup_url = newBackups;
            });
        });

        if (dirty) {
            count++;
            render();
            console.log('%c[PCDN Killer] CDN源已替换为正规线路', 'color:#00c853;font-weight:bold');
        }

        return json;
    }

    /* ════════ Hook fetch ════════ */
    var _fetch = window.fetch;
    window.fetch = function (input) {
        var url = typeof input === 'string' ? input : (input && input.url) || '';
        var isPlay = /\/playurl/i.test(url);

        if (enabled && isPCDN(url) && isSegment(url)) {
            count++;
            render();
            console.log('%c[PCDN Killer] 拦截分片', 'color:#ff9800', url.slice(0, 100));
            return Promise.reject(new DOMException('blocked', 'AbortError'));
        }

        return _fetch.apply(this, arguments).then(function (res) {
            if (!enabled || !isPlay) return res;
            return res.clone().text().then(function (text) {
                try {
                    var filtered = replaceCDN(JSON.parse(text));
                    return new Response(JSON.stringify(filtered), {
                        status: res.status,
                        statusText: res.statusText,
                        headers: res.headers
                    });
                } catch (_) { return res; }
            });
        });
    };

    /* ════════ Hook XMLHttpRequest ════════ */
    var _open = XMLHttpRequest.prototype.open;
    var _send = XMLHttpRequest.prototype.send;
    var _rtDesc = Object.getOwnPropertyDescriptor(XMLHttpRequest.prototype, 'responseText');

    XMLHttpRequest.prototype.open = function (m, u) {
        this._u = u;
        this._isPlay = /\/playurl/i.test(u);
        return _open.apply(this, arguments);
    };

    XMLHttpRequest.prototype.send = function () {
        var self = this;

        if (enabled && isPCDN(this._u) && isSegment(this._u)) {
            count++;
            render();
            console.log('%c[PCDN Killer] XHR拦截', 'color:#ff9800', this._u.slice(0, 100));
            try { this.abort(); } catch (_) { /* ignore */ }
            return;
        }

        if (enabled && this._isPlay) {
            this.addEventListener('readystatechange', function () {
                if (self.readyState !== 4 || self.status !== 200) return;
                try {
                    var text = _rtDesc.get.call(self);
                    var filtered = replaceCDN(JSON.parse(text));
                    var out = JSON.stringify(filtered);
                    Object.defineProperty(self, 'responseText', { value: out, writable: true, configurable: true });
                    Object.defineProperty(self, 'response', { value: out, writable: true, configurable: true });
                } catch (_) { /* ignore */ }
            });
        }

        return _send.apply(this, arguments);
    };

    /* ════════ 指示器 ════════ */
    function pos() {
        var sels = ['#viewbox_report h1', '.video-title-href', 'h1.video-title', '.video-title'];
        for (var i = 0; i < sels.length; i++) {
            var el = document.querySelector(sels[i]);
            if (!el) continue;
            var r = el.getBoundingClientRect();
            if (r.width > 0 && r.height > 0) {
                return { top: r.top + scrollY + (r.height - 28) / 2, left: r.right + 12 };
            }
        }
        return { top: 70, left: 10 };
    }

    function build() {
        var el = document.getElementById(IND) || document.createElement('div');
        el.id = IND;
        var p = pos();
        var bg = enabled ? 'linear-gradient(135deg,#00c853,#00a843)' : 'linear-gradient(135deg,#e53935,#c62828)';
        var label = enabled ? 'PCDN拦截' : 'PCDN·关';
        if (enabled && count > 0) label += ' · ' + count;

        el.style.cssText = 'position:absolute;top:' + p.top + 'px;left:' + p.left + 'px;display:inline-flex;align-items:center;gap:5px;padding:3px 12px 3px 9px;border-radius:14px;font-size:12px;font-weight:600;color:#fff;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;cursor:pointer;user-select:none;line-height:1.6;background:' + bg + ';box-shadow:0 1px 6px rgba(0,0,0,.25);z-index:99999;transition:background .3s';
        el.innerHTML = '<span style="display:inline-block;width:7px;height:7px;border-radius:50%;background:#fff"></span><span>' + label + '</span>';
        el.title = 'PCDN拦截: ' + (enabled ? '开启' : '关闭') + (enabled && count ? '\n本次拦截 ' + count + ' 次' : '') + '\n点击切换';
        el.onclick = toggle;
        return el;
    }

    function render() {
        var old = document.getElementById(IND);
        if (old) old.replaceWith(build());
    }

    function ensure() {
        if (!document.body) return;
        document.getElementById(IND) ? render() : document.body.appendChild(build());
    }

    /* ════════ 开关 ════════ */
    function toggle() {
        enabled = !enabled;
        if (!enabled) count = 0;
        localStorage.setItem(KEY, enabled ? '1' : '0');
        render();
    }

    try { GM_registerMenuCommand('PCDN拦截切换', toggle); } catch (_) { /* ignore */ }

    /* ════════ 定时守护 ════════ */
    setInterval(function () { if (document.body) ensure(); }, 1000);

    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', ensure);
    } else {
        ensure();
    }

})();