// ==UserScript==
// @name         粉笔课程课件下载器
// @namespace    https://www.fenbi.com/
// @version      1.1.0
// @description  进入粉笔课程回放页后自动捕获 keynote 文件并下载（双重下载机制：脚本管理器下载 + 原生浏览器触发，支持 IDM/Motrix/Aria 劫持）
// @author       超子&TraeWork
// @license      CC BY-NC 4.0
// @match        https://www.fenbi.com/spa/pwa/class/*
// @match        https://*.fenbi.com/spa/pwa/class/*
// @grant        unsafeWindow
// @grant        GM_download
// @grant        GM_xmlhttpRequest
// @run-at       document-start
// ==/UserScript==

(function () {
    'use strict';

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

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

    // 下载方式一：脚本管理器原生下载（跨域可用，不受浏览器限制）
    function downloadViaGM(url, filename) {
        if (typeof GM_download !== 'undefined') {
            try {
                GM_download({
                    url: url,
                    name: filename,
                    saveAs: false,
                    onload: function () {
                        console.log('[粉笔课件下载器] GM_download 下载完成: ' + filename);
                    },
                    onerror: function (err) {
                        console.warn('[粉笔课件下载器] GM_download 失败，尝试 fallback:', err);
                        downloadViaBlob(url, filename);
                    }
                });
                return true;
            } catch (e) {
                console.warn('[粉笔课件下载器] GM_download 调用失败:', e);
            }
        }
        return false;
    }

    // 下载方式二：GM_xmlhttpRequest + Blob（脚本管理器的另一种方式）
    function downloadViaBlob(url, filename) {
        if (typeof GM_xmlhttpRequest === 'undefined') {
            downloadViaAnchor(url, filename);
            return;
        }
        try {
            GM_xmlhttpRequest({
                method: 'GET',
                url: url,
                responseType: 'blob',
                onload: function (resp) {
                    if (resp.status === 200 && resp.response) {
                        var blobUrl = URL.createObjectURL(resp.response);
                        var a = document.createElement('a');
                        a.href = blobUrl;
                        a.download = filename;
                        a.style.display = 'none';
                        document.body.appendChild(a);
                        a.click();
                        document.body.removeChild(a);
                        setTimeout(function () { URL.revokeObjectURL(blobUrl); }, 1000);
                        console.log('[粉笔课件下载器] GM_xhr + Blob 下载完成: ' + filename);
                    } else {
                        downloadViaAnchor(url, filename);
                    }
                },
                onerror: function () {
                    downloadViaAnchor(url, filename);
                }
            });
        } catch (e) {
            downloadViaAnchor(url, filename);
        }
    }

    // 下载方式三：原生 a.click（用于被 IDM / Motrix / Aria 等下载工具劫持）
    function downloadViaAnchor(url, filename) {
        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('[粉笔课件下载器] 原生 a.click 下载触发: ' + filename);
    }

    function triggerDownload(url) {
        var hash = extractHash(url);
        var filename = hash ? hash + '.pdf' : 'keynote.pdf';

        // 优先用脚本管理器下载（保证能下到文件）
        var gmOk = downloadViaGM(url, filename);

        // 同时也触发原生 a.click（让 IDM/Motrix 等下载工具能劫持到）
        // 延迟一小段，避免和 GM_download 同时开始造成混乱
        setTimeout(function () {
            downloadViaAnchor(url, filename);
        }, 500);

        showNotification('已下载课件: ' + filename);
    }

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

        setTimeout(function () {
            triggerDownload(url);
        }, 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.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('[粉笔课件下载器] 脚本已加载 v1.1.0，等待捕获 keynote URL...');
})();