// ==UserScript==
// @name         行业标准/团体标准信息PDF下载
// @namespace    http://tampermonkey.net/
// @version      2026.4.8
// @description  自动下载行业标准/团体标准信息图片并合并为PDF（带进度显示），基于行业标准信息PDF下载改进
// @author       yangwenren
// @match        https://hbba.sacinfo.org.cn/attachment/onlineRead/*
// @match        https://www.ttbz.org.cn/kkfileview/onlinePreview*
// @match        https://ttbz.org.cn/kkfileview/onlinePreview*
// @require      https://cdnjs.cloudflare.com/ajax/libs/jspdf/2.5.1/jspdf.umd.min.js
// @grant        GM_xmlhttpRequest
// @grant        GM_download
// @grant        GM_notification
// @connect      hbba.sacinfo.org.cn
// @connect      www.ttbz.org.cn
// @connect      ttbz.org.cn
// ==/UserScript==

(function() {
    'use strict';
    
    const hostname = window.location.hostname;
    const pathname = window.location.pathname;
    const isTtbzPreview = (hostname === 'ttbz.org.cn' || hostname === 'www.ttbz.org.cn') && pathname.indexOf('/kkfileview/onlinePreview') === 0;

    const pathParts = pathname.split('/');
    const hbbaName = pathParts[3] || 'default_hash';
    let pageNum = 0;
    let imgUrls = [];
    const doc = new jspdf.jsPDF();
    let downloadBtn = null;

    // 验证页面（仅 hbba 阅读页）
    if (!isTtbzPreview) {
        if (!hbbaName || pathParts[2] !== 'onlineRead') {
            GM_notification({text: '请在标准阅读页面使用本脚本！', timeout: 5000});
            return;
        }
    }

    function decodeBase64ToUtf8(base64) {
        // 兼容 base64/base64url 两种形式
        let s = String(base64 || '').replace(/ /g, '+').replace(/-/g, '+').replace(/_/g, '/');
        // 补齐 padding
        const padLen = s.length % 4;
        if (padLen) s += '='.repeat(4 - padLen);

        const binary = atob(s);
        const bytes = Uint8Array.from(binary, c => c.charCodeAt(0));
        return new TextDecoder('utf-8').decode(bytes);
    }

    function sanitizeFileName(fileName) {
        // Windows 文件名禁用字符处理
        return String(fileName || '')
            .replace(/[\\/:*?"<>|]/g, '_')
            .trim() || 'download.pdf';
    }

    function createButton() {
        downloadBtn = document.createElement('button');
        downloadBtn.id = 'pdfDownloadBtn';
        downloadBtn.style = `
            position: fixed;
            top: 20px;
            right: 20px;
            padding: 7px 15px;
            background: #219677;
            color: white;
            border: none;
            border-radius: 4px;
            cursor: pointer;
            z-index: 9999;
            box-shadow: 0 2px 5px rgba(0,0,0,0.3);
            transition: all 0.3s;
        `;
        downloadBtn.textContent = '下载PDF';
        downloadBtn.onclick = startDownload;
        document.body.appendChild(downloadBtn);
    }

    function startDownload() {
        if (isTtbzPreview) {
            startDownloadTtbz();
            return;
        }

        // 重置状态
        pageNum = 0;
        imgUrls = [];
        updateButton('准备下载...', true);
        
        fetchNextPage();
    }

    function updateButton(text, disabled = false) {
        if (!downloadBtn) return;
        downloadBtn.textContent = text;
        downloadBtn.style.background = disabled ? '#808080' : '#219677';
        downloadBtn.disabled = disabled;
    }

    function fetchNextPage() {
        const url = `https://hbba.sacinfo.org.cn/hbba_onlineRead_page/${hbbaName}/${pageNum}.png?t=1`;
        
        GM_xmlhttpRequest({
            method: 'GET',
            url: url,
            responseType: 'blob',
            headers: {
                'Referer': 'https://hbba.sacinfo.org.cn/',
                'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36'
            },
            onload: function(response) {
                if (response.status === 200) {
                    const blob = response.response;
                    imgUrls.push(URL.createObjectURL(blob));
                    pageNum++;
                    updateButton(`下载中...（已下载 ${pageNum} 页）`, true);
                    setTimeout(fetchNextPage, 1000);
                } else {
                    endDownload();
                }
            },
            onerror: function() {
                endDownload();
            }
        });
    }

    function endDownload() {
        if (pageNum === 0) {
            updateButton('下载失败，点击重试');
            GM_notification({text: '下载失败，请重试！', timeout: 3000});
            return;
        }
        
        updateButton('生成PDF中...', true);
        
        generatePDF();
    }

    function generatePDF() {
        if (imgUrls.length === 0) return;

        const img = new Image();
        img.src = imgUrls[0];
        img.onload = function() {
            const imgWidth = doc.internal.pageSize.getWidth();
            const imgHeight = (img.height * imgWidth) / img.width;

            doc.addImage(imgUrls[0], 'JPEG', 0, 0, imgWidth, imgHeight);
            
            for (let i = 1; i < imgUrls.length; i++) {
                doc.addPage();
                doc.addImage(imgUrls[i], 'JPEG', 0, 0, imgWidth, imgHeight);
            }

            doc.save(`${hbbaName}.pdf`);
            
            // 清理资源
            imgUrls.forEach(url => URL.revokeObjectURL(url));
            updateButton('下载完成 ✔️');
            setTimeout(() => updateButton('下载PDF'), 5000);
        };
    }

    function startDownloadTtbz() {
        updateButton('解析下载链接...', true);

        const params = new URLSearchParams(window.location.search);
        const encodedUrl = params.get('url');
        if (!encodedUrl) {
            updateButton('链接缺失，重试', false);
            GM_notification({text: '未找到参数 `url=`，请确保在 tt bz 预览页打开后再点下载', timeout: 5000});
            return;
        }

        let pdfUrl = '';
        try {
            pdfUrl = decodeBase64ToUtf8(encodedUrl);
        } catch (e) {
            console.error(e);
            updateButton('链接解析失败', false);
            GM_notification({text: '解析 `url=`（Base64）失败，请检查链接格式', timeout: 5000});
            return;
        }

        // 从解码后的真实地址尝试抽取文件名（fullfilename）
        let fileName = 'download.pdf';
        try {
            const u = new URL(pdfUrl);
            const full = u.searchParams.get('fullfilename');
            if (full) fileName = full;
        } catch (e) {
            const m = pdfUrl.match(/([^/?#]+\.pdf)(?:$|[?#])/i);
            if (m) fileName = m[1];
        }
        fileName = sanitizeFileName(fileName);
        if (!fileName.toLowerCase().endsWith('.pdf')) fileName += '.pdf';

        updateButton('开始下载PDF...', true);
        GM_xmlhttpRequest({
            method: 'GET',
            url: pdfUrl,
            responseType: 'blob',
            headers: {
                'Referer': window.location.origin + '/',
                'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36'
            },
            onload: function(response) {
                if (response.status === 200 || response.status === 0) {
                    const blob = response.response;
                    const blobUrl = URL.createObjectURL(blob);

                    const a = document.createElement('a');
                    a.href = blobUrl;
                    a.download = fileName;
                    document.body.appendChild(a);
                    a.click();
                    a.remove();

                    setTimeout(() => URL.revokeObjectURL(blobUrl), 30000);
                    updateButton('下载完成 ✔️', false);
                    setTimeout(() => updateButton('下载PDF', false), 5000);
                } else {
                    console.error('ttbz download failed:', response.status);
                    updateButton('下载失败，重试', false);
                    GM_notification({text: 'ttbz 下载失败，可能需要登录或链接已过期', timeout: 5000});
                }
            },
            onerror: function() {
                updateButton('下载失败，重试', false);
                GM_notification({text: 'ttbz 下载失败，请重试', timeout: 5000});
            }
        });
    }

    // 初始化
    if (isTtbzPreview) {
        setTimeout(createButton, 1000);
    } else if (hbbaName !== 'default_hash') {
        setTimeout(createButton, 1000);
    }
})();