// ==UserScript==
// @name         粉笔 Keynote 下载器
// @namespace    https://www.fenbi.com/
// @version      1.0.0
// @description  进入粉笔课程回放页后自动捕获 keynote 文件并下载（原生浏览器下载，支持 IDM/Aria 劫持）
// @author       You
// @match        https://www.fenbi.com/spa/pwa/class/*
// @match        https://*.fenbi.com/spa/pwa/class/*
// @grant        unsafeWindow
// @run-at       document-start
// ==/UserScript==

(function () {
    'use strict';

    var win = (typeof unsafeWindow !== 'undefined') ? unsafeWindow : window;
    var captured = false;
    var keynoteUrl = null;

    function triggerDownload(url) {
        var hash = extractHash(url);
        var filename = hash ? hash + '.pdf' : 'keynote.pdf';
        var a = document.createElement('a');
        a.href = url;
        a.download = filename;
        a.style.display = 'none';
        document.body.appendChild(a);
        a.click();
        document.body.removeChild(a);
        console.log('[粉笔Keynote下载器] 已触发下载: ' + filename);
    }

    function extractHash(url) {
        var m = url.match(/keynotes\/([a-f0-9]+)/i);
        return m ? m[1] : null;
    }

    function onKeynoteFound(url) {
        if (captured) return;
        captured = true;
        keynoteUrl = url;
        console.log('[粉笔Keynote下载器] 捕获到 keynote URL: ' + url);

        setTimeout(function () {
            triggerDownload(url);
            showNotification('已下载 keynote: ' + (extractHash(url) || 'unknown') + '.pdf');
        }, 2000);
    }

    function showNotification(msg) {
        var div = document.createElement('div');
        div.textContent = msg;
        div.style.cssText = 'position:fixed;top:20px;right:20px;z-index:99999;' +
            'background:#4CAF50;color:white;padding:12px 20px;border-radius:8px;' +
            'font-size:14px;font-family:sans-serif;box-shadow:0 4px 12px rgba(0,0,0,0.3);' +
            'transition:opacity 0.5s;opacity:1;';
        document.body.appendChild(div);
        setTimeout(function () { div.style.opacity = '0'; }, 4000);
        setTimeout(function () { if (div.parentNode) div.parentNode.removeChild(div); }, 5000);
    }

    function installHooks() {
        var origOpen = win.XMLHttpRequest.prototype.open;
        win.XMLHttpRequest.prototype.open = function (method, url) {
            if (url && typeof url === 'string' && url.indexOf('keynoteali') !== -1 ||
                (url && typeof url === 'string' && url.indexOf('keynotes/') !== -1 && url.indexOf('fbstatic') !== -1)) {
                onKeynoteFound(url);
            }
            return origOpen.apply(this, arguments);
        };

        if (win.fetch) {
            var origFetch = win.fetch;
            win.fetch = function () {
                var url = arguments[0];
                if (typeof url === 'string' && (url.indexOf('keynoteali') !== -1 || url.indexOf('keynotes/') !== -1)) {
                    onKeynoteFound(url);
                } else if (url && url.url && typeof url.url === 'string' && url.url.indexOf('keynoteali') !== -1) {
                    onKeynoteFound(url.url);
                }
                return origFetch.apply(this, arguments);
            };
        }
    }

    function scanPerformanceEntries() {
        if (captured) return;
        try {
            var resources = win.performance.getEntriesByType('resource');
            for (var i = 0; i < resources.length; i++) {
                var name = resources[i].name;
                if (name.indexOf('keynoteali') !== -1 || (name.indexOf('keynotes/') !== -1 && name.indexOf('fbstatic') !== -1)) {
                    onKeynoteFound(name);
                    return;
                }
            }
        } catch (e) {}
    }

    var observer = null;
    function startObserver() {
        if (typeof win.PerformanceObserver === 'undefined') return;
        try {
            observer = new win.PerformanceObserver(function (list) {
                var entries = list.getEntries();
                for (var i = 0; i < entries.length; i++) {
                    var name = entries[i].name;
                    if (name.indexOf('keynoteali') !== -1 || (name.indexOf('keynotes/') !== -1 && name.indexOf('fbstatic') !== -1)) {
                        onKeynoteFound(name);
                    }
                }
            });
            observer.observe({ entryTypes: ['resource'] });
        } catch (e) {}
    }

    installHooks();
    startObserver();

    var scanCount = 0;
    var scanTimer = setInterval(function () {
        scanCount++;
        scanPerformanceEntries();
        if (captured || scanCount > 30) {
            clearInterval(scanTimer);
        }
    }, 1000);

    console.log('[粉笔Keynote下载器] 脚本已加载，等待捕获 keynote URL...');
})();