// ==UserScript==
// @name         AO3助手
// @namespace    https://greasyfork.org/users/1384897
// @version      0.7
// @description  下载AO3 tag/详情页/作者页文章为EPUB
// @author       ✌
// @match        https://archiveofourown.org/tags/*/works*
// @match        https://archiveofourown.org/works?*
// @match        https://archiveofourown.org/*
// @grant        GM_xmlhttpRequest
// @connect      archiveofourown.org
// @connect      download.archiveofourown.org
// @license      MIT
// @downloadURL none
// ==/UserScript==

(function () {
    'use strict';

    const maxWorks = 1000;
    const delay = 4000;
    let worksProcessed = Number(localStorage.getItem('worksProcessed')) || 0;
    let isDownloading = false;
    let downloadInterrupted = false;

    const style = document.createElement('style');
    style.textContent = `
      .ao3-helper-btn {
        position: fixed;
        right: 10px;
        top: 95px;
        z-index: 999999;
        padding: 8px 14px;
        border: none;
        border-radius: 6px;
        background: #1e90ff;
        color: #fff;
        font-size: 13px;
        font-weight: 500;
        cursor: pointer;
        box-shadow: 0 2px 8px rgba(0,0,0,.15);
        transition: opacity .2s, transform .15s;
        white-space: nowrap;
      }
      .ao3-helper-btn:hover  { opacity: .9; transform: translateY(-1px); }
      .ao3-helper-btn:active { transform: translateY(0); }
      .ao3-helper-btn:disabled { opacity: .6; cursor: not-allowed; }
    `;
    document.head.appendChild(style);

    const button = document.createElement('button');
    button.className = 'ao3-helper-btn';
    button.innerText = '开始下载';
    document.body.appendChild(button);

    const isSingleWork = /\/works\/\d+/.test(window.location.pathname);

    button.addEventListener('click', () => {
        if (isSingleWork) {
            downloadCurrentWork();
            return;
        }
        if (isDownloading) {
            downloadInterrupted = true;
            button.innerText = '开始下载';
            localStorage.setItem('stopFlag', 'true');
            localStorage.removeItem('worksProcessed');
            worksProcessed = 0;
            isDownloading = false;
            location.reload();
        } else {
            localStorage.removeItem('stopFlag');
            downloadInterrupted = false;
            startDownload();
        }
    });

    if (localStorage.getItem('worksProcessed') && localStorage.getItem('stopFlag') !== 'true') {
        startDownload();
    }

    function downloadCurrentWork() {
        const title = document.querySelector('h2.title')?.textContent.trim() || '无标题';
        const author = document.querySelector('a[rel="author"]')?.textContent.trim() || '匿名';
        const epubHref = document.querySelector('li.download ul a[href*=".epub"]')?.getAttribute('href');
        if (!epubHref) {
            alert('未找到epub下载链接');
            return;
        }
        const safeTitle = title.replace(/[\/:*?"<>|]/g, '');
        const safeAuthor = author.replace(/[\/:*?"<>|]/g, '');
        const filename = `${safeTitle}_${safeAuthor}.epub`;
        const epubUrl = `https://download.archiveofourown.org${epubHref}`;
        button.innerText = '下载中...';
        button.disabled = true;
        GM_xmlhttpRequest({
            method: 'GET',
            url: epubUrl,
            responseType: 'blob',
            onload: res => {
                const a = document.createElement('a');
                a.href = URL.createObjectURL(res.response);
                a.download = filename;
                a.click();
                URL.revokeObjectURL(a.href);
                button.innerText = '下载完成';
                button.disabled = false;
            },
            onerror: () => {
                button.innerText = '下载失败';
                button.disabled = false;
            }
        });
    }

    function startDownload() {
        console.log(`开始下载最多 ${maxWorks} 篇作品...`);
        isDownloading = true;
        updateButtonProgress();
        processPage(window.location.href);
    }

    function processWorksWithDelay(workLinks, index = 0, pageDoc) {
        if (downloadInterrupted || index >= workLinks.length || worksProcessed >= maxWorks) {
            checkForNextPage(pageDoc);
            return;
        }

        const { workUrl } = workLinks[index];
        GM_xmlhttpRequest({
            method: 'GET',
            url: workUrl,
            onload: response => {
                if (downloadInterrupted) return;

                const parser = new DOMParser();
                const doc = parser.parseFromString(response.responseText, "text/html");
                const title = doc.querySelector('h2.title')?.textContent.trim() || '无标题';
                const author = doc.querySelector('a[rel="author"]')?.textContent.trim() || '匿名';

                const epubHref = doc.querySelector('li.download ul a[href*=".epub"]')?.getAttribute('href');
                if (!epubHref) {
                    setTimeout(() => processWorksWithDelay(workLinks, index + 1, pageDoc), delay);
                    return;
                }

                const safeTitle = title.replace(/[\/:*?"<>|]/g, '');
                const safeAuthor = author.replace(/[\/:*?"<>|]/g, '');
                const filename = `${safeTitle}_${safeAuthor}.epub`;
                const epubUrl = `https://download.archiveofourown.org${epubHref}`;

                GM_xmlhttpRequest({
                    method: 'GET',
                    url: epubUrl,
                    responseType: 'blob',
                    onload: res => {
                        const a = document.createElement('a');
                        a.href = URL.createObjectURL(res.response);
                        a.download = filename;
                        a.click();
                        URL.revokeObjectURL(a.href);
                    },
                    onerror: e => console.error(`[AO3] 下载失败: ${filename}`, e)
                });

                worksProcessed++;
                localStorage.setItem('worksProcessed', worksProcessed);
                updateButtonProgress();

                setTimeout(() => processWorksWithDelay(workLinks, index + 1, pageDoc), delay);
            },
            onerror: () => {
                console.error(`加载内容失败: ${workUrl}`);
                setTimeout(() => processWorksWithDelay(workLinks, index + 1, pageDoc), delay);
            }
        });
    }

    function processPage(url) {
        GM_xmlhttpRequest({
            method: 'GET',
            url: url,
            onload: response => {
                const parser = new DOMParser();
                const doc = parser.parseFromString(response.responseText, "text/html");
                const workLinks = Array.from(doc.querySelectorAll('h4.heading a'))
                    .filter(a => /\/works\/\d+$/.test(a.pathname))
                    .map(a => ({ workUrl: `${a.href}?view_adult=true` }));
                processWorksWithDelay(workLinks, 0, doc);
            },
            onerror: () => console.error(`加载页面失败: ${url}`)
        });
    }

    function checkForNextPage(doc) {
        if (worksProcessed >= maxWorks || downloadInterrupted) {
            completeAndReset();
            return;
        }

        const nextLink = doc.querySelector('a[rel="next"]');
        if (nextLink) {
            const nextPageUrl = new URL(nextLink.href, window.location.origin).toString();
            console.log('跳转下一页:', nextPageUrl);
            window.location.href = nextPageUrl;
        } else {
            completeAndReset();
        }
    }

    function completeAndReset() {
        console.log('下载完成，清空记录。');
        localStorage.clear();
        worksProcessed = 0;
        isDownloading = false;
        location.reload();
    }

    function updateButtonProgress() {
        button.innerText = `下载中 - 进度：${worksProcessed}/${maxWorks}`;
    }
})();