// ==UserScript==
// @name         AO3 Helper
// @name:zh-CN   AO3 助手
// @description  Batch download AO3 works as EPUB, supports tag/author/work pages with auto-pagination
// @description:zh-CN  批量下载 AO3 作品为 EPUB，支持 tag 页、作者页、详情页，自动翻页
// @namespace    http://tampermonkey.net/
// @version      1.2
// @author       Lumiarna
// @match        http*://archiveofourown.org/*
// @grant        GM_xmlhttpRequest
// @connect      archiveofourown.org
// @connect      download.archiveofourown.org
// @license      MIT
// @downloadURL none
// ==/UserScript==

(function () {
    'use strict';

    const DOWNLOAD_BASE = 'https://download.archiveofourown.org';
    const KEYS = {
        maxWorks: 'ao3_helper_maxWorks',
        processed: 'ao3_helper_worksProcessed',
        stopFlag: 'ao3_helper_stopFlag',
        originUrl: 'ao3_helper_downloadOriginUrl',
    };

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

    // ────── UI ──────

    const style = document.createElement('style');
    style.textContent = `
      .ao3-helper-btn {
        position: fixed;
        right: 10px;
        top: 90px;
        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; }
      .ao3-gear-btn {
        position: fixed;
        right: 10px;
        top: 130px;
        z-index: 999999;
        padding: 6px 10px;
        border: none;
        border-radius: 6px;
        background: #555;
        color: #fff;
        font-size: 16px;
        cursor: pointer;
        box-shadow: 0 2px 8px rgba(0,0,0,.15);
        transition: opacity .2s, transform .3s;
        line-height: 1;
      }
      .ao3-gear-btn:hover { opacity: .85; transform: rotate(45deg); }
      .ao3-settings-modal {
        position: fixed;
        right: 60px;
        top: 125px;
        z-index: 9999999;
        background: #fff;
        border: 1px solid #ddd;
        border-radius: 10px;
        box-shadow: 0 4px 20px rgba(0,0,0,.2);
        padding: 16px;
        min-width: 240px;
        font-size: 13px;
        color: #333;
      }
      .ao3-settings-modal h3 {
        margin: 0 0 12px;
        font-size: 14px;
        font-weight: 600;
        border-bottom: 1px solid #eee;
        padding-bottom: 8px;
      }
      .ao3-settings-modal label {
        display: block;
        margin-bottom: 4px;
        font-weight: 500;
        color: #555;
      }
      .ao3-settings-modal input {
        width: 100%;
        box-sizing: border-box;
        padding: 5px 8px;
        border: 1px solid #ccc;
        border-radius: 5px;
        font-size: 13px;
        margin-bottom: 10px;
      }
      .ao3-settings-modal .ao3-settings-note {
        font-size: 11px;
        color: #999;
        margin-top: -8px;
        margin-bottom: 10px;
      }
      .ao3-settings-save {
        width: 100%;
        padding: 6px;
        background: #1e90ff;
        color: #fff;
        border: none;
        border-radius: 5px;
        cursor: pointer;
        font-size: 13px;
        font-weight: 500;
      }
      .ao3-settings-save:hover { opacity: .9; }
    `;
    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 gearBtn = document.createElement('button');
    gearBtn.className = 'ao3-gear-btn';
    gearBtn.title = '下载设置';
    gearBtn.textContent = '⚙';
    document.body.appendChild(gearBtn);

    const modal = document.createElement('div');
    modal.className = 'ao3-settings-modal';
    modal.style.display = 'none';
    modal.innerHTML = `
      <h3>下载设置</h3>
      <label>最大下载数量</label>
      <input id="ao3-max-input" type="number" min="1" max="99999" />
      <button class="ao3-settings-save" id="ao3-settings-save">保存</button>
    `;
    document.body.appendChild(modal);

    modal.querySelector('#ao3-max-input').value = maxWorks;

    gearBtn.addEventListener('click', (e) => {
        e.stopPropagation();
        modal.style.display = modal.style.display === 'none' ? 'block' : 'none';
    });

    modal.querySelector('#ao3-settings-save').addEventListener('click', () => {
        const max = parseInt(modal.querySelector('#ao3-max-input').value, 10);
        if (max > 0) {
            maxWorks = max;
            localStorage.setItem(KEYS.maxWorks, max);
        }
        modal.style.display = 'none';
        if (isDownloading) updateButtonProgress();
    });

    document.addEventListener('click', (e) => {
        if (modal.style.display === 'none') return;
        if (!modal.contains(e.target) && e.target !== gearBtn) {
            modal.style.display = 'none';
        }
    });

    // ────── 公共工具函数 ──────

    const sanitize = s => s.replace(/[\/:*?"<>|]/g, '');

    function extractWorkInfo(doc) {
        const title = doc.querySelector('h2.title')?.textContent.trim() || '无标题';
        const author = doc.querySelector('a[rel="author"]')?.textContent.trim() || 'Anonymous';
        const epubHref = doc.querySelector('li.download ul a[href*=".epub"]')?.getAttribute('href');
        if (!epubHref) return null;
        return {
            filename: `${sanitize(title)}_${sanitize(author)}.epub`,
            epubUrl: `${DOWNLOAD_BASE}${epubHref}`,
        };
    }

    function gmFetch(opts, label) {
        return new Promise((resolve) => {
            let attempt = 0;
            (function tryOnce() {
                if (downloadInterrupted) return;
                GM_xmlhttpRequest({
                    ...opts,
                    onload: resolve,
                    onerror: () => {
                        attempt++;
                        const wait = Math.min(attempt * 5, 60);
                        button.innerText = `${label} 重试 #${attempt}（${wait}s 后）`;
                        setTimeout(tryOnce, wait * 1000);
                    },
                });
            })();
        });
    }

    function downloadEpub(url, filename) {
        return gmFetch({ method: 'GET', url, responseType: 'blob' }, `下载 ${filename}`)
            .then(res => saveBlob(res.response, filename));
    }

    function saveBlob(blob, filename) {
        const url = URL.createObjectURL(blob);
        const a = document.createElement('a');
        a.href = url;
        a.download = filename;
        a.click();
        setTimeout(() => URL.revokeObjectURL(url), 60_000);
    }

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

    // ────── 单篇下载 ──────

    function downloadCurrentWork() {
        const info = extractWorkInfo(document);
        if (!info) {
            alert('未找到epub下载链接');
            return;
        }
        button.innerText = '下载中...';
        button.disabled = true;
        downloadEpub(info.epubUrl, info.filename).then(() => {
            button.innerText = '下载完成';
            button.disabled = false;
        });
    }

    // ────── 批量下载 ──────

    function startDownload() {
        worksProcessed = 0;
        localStorage.removeItem(KEYS.processed);
        console.log(`开始下载最多 ${maxWorks} 篇作品...`);
        isDownloading = true;
        updateButtonProgress();
        processDoc(document);
    }

    function processDoc(doc) {
        const workLinks = Array.from(doc.querySelectorAll('li.work.blurb h4.heading a'))
            .filter(a => /\/works\/\d+$/.test(a.pathname))
            .map(a => `${a.href}?view_adult=true`);
        processWorksWithDelay(workLinks, 0, doc);
    }

    async function processWorksWithDelay(workLinks, index = 0, pageDoc) {
        for (let i = index; i < workLinks.length && !downloadInterrupted && worksProcessed < maxWorks; i++) {
            const response = await gmFetch({ method: 'GET', url: workLinks[i] }, `加载作品 ${i + 1}/${workLinks.length}`);
            if (downloadInterrupted) return;

            const doc = new DOMParser().parseFromString(response.responseText, 'text/html');
            const info = extractWorkInfo(doc);
            if (info) {
                downloadEpub(info.epubUrl, info.filename);
                worksProcessed++;
                localStorage.setItem(KEYS.processed, worksProcessed);
            }
            updateButtonProgress();
            await new Promise(r => setTimeout(r, delay));
        }
        checkForNextPage(pageDoc);
    }

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

        const nextLink = doc.querySelector('li.next a');
        if (nextLink) {
            const nextPageUrl = new URL(nextLink.href, window.location.origin).toString();
            console.log('跳转下一页:', nextPageUrl);
            localStorage.setItem(KEYS.originUrl, nextPageUrl);
            window.location.href = nextPageUrl;
        } else {
            completeAndReset();
        }
    }

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

    // ────── 入口 ──────

    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(KEYS.stopFlag, 'true');
            localStorage.removeItem(KEYS.processed);
            worksProcessed = 0;
            isDownloading = false;
            location.reload();
        } else {
            localStorage.removeItem(KEYS.stopFlag);
            downloadInterrupted = false;
            startDownload();
        }
    });

    const savedUrl = localStorage.getItem(KEYS.originUrl);
    if (savedUrl && savedUrl === window.location.href && localStorage.getItem(KEYS.processed) && localStorage.getItem(KEYS.stopFlag) !== 'true') {
        isDownloading = true;
        updateButtonProgress();
        processDoc(document);
    }
})();