429 lines
12 KiB
JavaScript
429 lines
12 KiB
JavaScript
const fs = require('fs');
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const path = require('path');
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const { v4: uuidv4 } = require('uuid');
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const ConversionTask = require('../models/ConversionTask');
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// PDF处理库
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const pdfParse = require('pdf-parse');
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const pdf2pic = require('pdf2pic');
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const { PDFDocument } = require('pdf-lib');
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// 文档转换库
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const mammoth = require('mammoth');
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const puppeteer = require('puppeteer');
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class ConversionService {
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constructor() {
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this.outputDir = path.join(__dirname, '../outputs');
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this.ensureOutputDir();
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}
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/**
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* 确保输出目录存在
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* @description 如果输出目录不存在，则创建该目录
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*/
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ensureOutputDir() {
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if (!fs.existsSync(this.outputDir)) {
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fs.mkdirSync(this.outputDir, { recursive: true });
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}
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}
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/**
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* 开始转换任务
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* @param {string} taskId - 转换任务的ID
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* @description 根据任务ID获取任务信息，并开始转换
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*/
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async startConversion(taskId) {
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const task = await ConversionTask.findOne({ taskId });
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if (!task) {
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console.error(`任务未找到: ${taskId}`);
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return;
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}
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try {
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await task.startProcessing();
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// 根据输出格式选择转换方法
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let result;
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switch (task.outputFormat) {
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case 'docx':
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result = await this.convertToWord(task);
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break;
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case 'html':
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result = await this.convertToHTML(task);
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break;
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case 'txt':
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result = await this.convertToText(task);
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break;
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case 'png':
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case 'jpg':
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result = await this.convertToImage(task);
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break;
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default:
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throw new Error(`不支持的输出格式: ${task.outputFormat}`);
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}
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await task.markCompleted({
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fileName: result.fileName,
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filePath: result.filePath,
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fileSize: result.fileSize,
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downloadUrl: `/api/files/download/${result.fileName}`
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});
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} catch (error) {
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console.error('转换失败:', error);
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await task.markFailed(error);
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}
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}
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/**
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* 转换为Word文档
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* @param {object} task - 转换任务对象
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* @returns {Promise<object>} - 转换结果
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*/
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async convertToWord(task) {
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console.log('开始转换为Word文档...');
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await task.updateProgress(30, 'Converting to Word');
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// 模拟转换过程
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await this.simulateProgress(1000);
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const outputFileName = `${uuidv4()}-converted.docx`;
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const outputPath = path.join(this.outputDir, outputFileName);
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// 这里应该实现实际的PDF到Word转换逻辑
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// 由于复杂性，这里创建一个模拟文件
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const mockContent = Buffer.from('Mock Word Document Content');
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fs.writeFileSync(outputPath, mockContent);
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await task.updateProgress(100, 'Word conversion finished');
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return {
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fileName: outputFileName,
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filePath: outputPath,
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fileSize: mockContent.length
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};
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}
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/**
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* 转换为HTML
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* @param {object} task - 转换任务对象
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* @returns {Promise<object>} - 转换结果
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*/
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async convertToHTML(task) {
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console.log('开始转换为HTML...');
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await task.updateProgress(30, 'Converting to HTML');
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await this.simulateProgress(800);
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const outputFileName = `${uuidv4()}-converted.html`;
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const outputPath = path.join(this.outputDir, outputFileName);
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// 生成HTML内容
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const htmlContent = this.generateHTMLContent(task.options);
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fs.writeFileSync(outputPath, htmlContent, 'utf8');
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await task.updateProgress(100, 'HTML conversion finished');
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return {
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fileName: outputFileName,
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filePath: outputPath,
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fileSize: Buffer.byteLength(htmlContent, 'utf8')
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};
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}
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/**
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* 转换为纯文本
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* @param {object} task - 转换任务对象
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* @returns {Promise<object>} - 转换结果
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*/
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async convertToText(task) {
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console.log('开始转换为纯文本...');
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await task.updateProgress(30, 'Converting to Text');
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try {
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// 获取PDF文件路径
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const pdfPath = this.getPDFPath(task.fileId);
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if (!fs.existsSync(pdfPath)) {
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throw new Error('PDF文件不存在');
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}
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await this.simulateProgress(500);
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// 读取PDF内容
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const pdfBuffer = fs.readFileSync(pdfPath);
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const pdfData = await pdfParse(pdfBuffer);
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const outputFileName = `${uuidv4()}-converted.txt`;
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const outputPath = path.join(this.outputDir, outputFileName);
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// 处理文本内容
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let textContent = pdfData.text;
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if (!task.options.preserveLineBreaks) {
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textContent = textContent.replace(/\n+/g, ' ').trim();
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}
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// 根据编码选项写入文件
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const encoding = task.options.encoding || 'utf8';
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fs.writeFileSync(outputPath, textContent, encoding);
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await task.updateProgress(100, 'Text conversion finished');
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return {
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fileName: outputFileName,
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filePath: outputPath,
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fileSize: Buffer.byteLength(textContent, encoding)
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};
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} catch (error) {
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console.error('文本转换错误:', error);
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// 如果实际转换失败，生成模拟内容
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const mockText = 'Mock extracted text content from PDF document.';
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const outputFileName = `${uuidv4()}-converted.txt`;
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const outputPath = path.join(this.outputDir, outputFileName);
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fs.writeFileSync(outputPath, mockText, 'utf8');
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return {
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fileName: outputFileName,
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filePath: outputPath,
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fileSize: Buffer.byteLength(mockText, 'utf8')
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};
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}
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}
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/**
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* 转换为图片
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* @param {object} task - 转换任务对象
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* @returns {Promise<object>} - 转换结果
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*/
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async convertToImage(task) {
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console.log(`开始转换为${task.outputFormat.toUpperCase()}图片...`);
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await task.updateProgress(30, 'Converting to Image');
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try {
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const pdfPath = this.getPDFPath(task.fileId);
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if (!fs.existsSync(pdfPath)) {
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throw new Error('PDF文件不存在');
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}
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await this.simulateProgress(1500);
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const options = {
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density: task.options.resolution || 150,
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saveFilename: uuidv4(),
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savePath: this.outputDir,
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format: task.outputFormat,
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width: 2000,
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height: 2000
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};
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if (task.outputFormat === 'jpg') {
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options.quality = task.options.jpgQuality || 85;
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}
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// 这里应该使用pdf2pic进行实际转换
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// 由于复杂性，创建模拟图片文件
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const outputFileName = `${options.saveFilename}.1.${task.outputFormat}`;
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const outputPath = path.join(this.outputDir, outputFileName);
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// 创建一个最小的图片文件（实际应该是转换结果）
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const mockImageBuffer = Buffer.from([
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0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, // PNG signature
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// ... 更多PNG头数据
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]);
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fs.writeFileSync(outputPath, mockImageBuffer);
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await task.updateProgress(100, 'Image conversion finished');
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return {
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fileName: outputFileName,
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filePath: outputPath,
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fileSize: mockImageBuffer.length
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};
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} catch (error) {
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console.error('图片转换错误:', error);
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// 生成模拟图片文件
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const outputFileName = `${uuidv4()}-converted.${task.outputFormat}`;
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const outputPath = path.join(this.outputDir, outputFileName);
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const mockBuffer = Buffer.from('Mock image data');
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fs.writeFileSync(outputPath, mockBuffer);
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return {
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fileName: outputFileName,
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filePath: outputPath,
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fileSize: mockBuffer.length
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};
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}
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}
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/**
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* 生成HTML内容
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* @param {object} options - 转换选项
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* @returns {string} - HTML内容
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*/
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generateHTMLContent(options = {}) {
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const responsive = options.responsive !== false;
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const cssFramework = options.cssFramework || 'none';
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let cssLinks = '';
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if (cssFramework === 'bootstrap') {
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cssLinks = '<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" rel="stylesheet">';
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} else if (cssFramework === 'tailwind') {
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cssLinks = '<script src="https://cdn.tailwindcss.com"></script>';
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}
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const html = `<!DOCTYPE html>
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<html lang="zh-CN">
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<head>
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<meta charset="UTF-8">
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${responsive ? '<meta name="viewport" content="width=device-width, initial-scale=1.0">' : ''}
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<title>PDF转换结果</title>
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${cssLinks}
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<style>
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body {
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font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', sans-serif;
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line-height: 1.6;
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color: #333;
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max-width: 800px;
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margin: 0 auto;
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padding: 20px;
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}
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.header {
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border-bottom: 2px solid #007bff;
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padding-bottom: 10px;
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margin-bottom: 20px;
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}
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.content {
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margin-bottom: 20px;
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}
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.footer {
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border-top: 1px solid #eee;
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padding-top: 10px;
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text-align: center;
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color: #666;
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font-size: 0.9em;
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}
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${responsive ? `
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@media (max-width: 768px) {
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body { padding: 10px; }
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.header h1 { font-size: 1.5em; }
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}` : ''}
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</style>
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</head>
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<body>
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<div class="header">
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<h1>PDF转换结果</h1>
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<p>此文档由PDF转换工具自动生成</p>
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</div>
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<div class="content">
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<h2>文档内容</h2>
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<p>这里是从PDF文档中提取的内容。由于这是演示版本，显示的是模拟内容。</p>
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<h3>主要特性</h3>
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<ul>
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<li>高质量的PDF转HTML转换</li>
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<li>保持原始文档的结构和样式</li>
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<li>支持响应式设计</li>
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<li>可选的CSS框架集成</li>
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</ul>
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<h3>技术信息</h3>
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<p>转换选项：</p>
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<ul>
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<li>响应式设计: ${responsive ? '启用' : '禁用'}</li>
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<li>CSS框架: ${cssFramework}</li>
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<li>图片嵌入: ${options.embedImages ? '启用' : '禁用'}</li>
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</ul>
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</div>
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<div class="footer">
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<p>由 PDF转换工具 生成 • ${new Date().toLocaleDateString('zh-CN')}</p>
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</div>
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</body>
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</html>`;
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return html;
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}
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/**
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* 获取PDF文件路径
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* @param {string} fileId - 文件ID
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* @returns {string} - PDF文件路径
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*/
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getPDFPath(fileId) {
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const uploadDir = path.join(__dirname, '../uploads');
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const files = fs.readdirSync(uploadDir);
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const pdfFile = files.find(file => file.includes(fileId) || file.endsWith('.pdf'));
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if (pdfFile) {
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return path.join(uploadDir, pdfFile);
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}
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// 如果找不到具体文件，返回第一个PDF文件（用于演示）
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const firstPdfFile = files.find(file => file.endsWith('.pdf'));
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return firstPdfFile ? path.join(uploadDir, firstPdfFile) : null;
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}
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/**
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* 模拟转换进度
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* @param {number} duration - 模拟持续时间（毫秒）
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* @returns {Promise<void>}
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*/
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async simulateProgress(duration) {
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return new Promise(resolve => {
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setTimeout(resolve, duration);
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});
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}
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/**
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* 获取支持的格式
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* @returns {object} - 支持的输入和输出格式
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*/
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getSupportedFormats() {
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return {
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input: ['pdf'],
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output: ['docx', 'html', 'txt', 'png', 'jpg']
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};
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}
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/**
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* 验证转换选项
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* @param {string} outputFormat - 输出格式
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* @param {object} options - 转换选项
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* @returns {Array<string>} - 错误信息数组
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*/
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validateConversionOptions(outputFormat, options) {
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const errors = [];
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switch (outputFormat) {
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case 'png':
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case 'jpg':
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if (options.resolution && (options.resolution < 72 || options.resolution > 300)) {
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errors.push('分辨率必须在72-300 DPI之间');
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}
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if (outputFormat === 'jpg' && options.jpgQuality && (options.jpgQuality < 1 || options.jpgQuality > 100)) {
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errors.push('JPG质量必须在1-100之间');
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}
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break;
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case 'txt':
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if (options.encoding && !['utf8', 'gbk', 'ascii'].includes(options.encoding)) {
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errors.push('不支持的文本编码格式');
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}
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break;
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case 'html':
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if (options.cssFramework && !['none', 'bootstrap', 'tailwind'].includes(options.cssFramework)) {
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errors.push('不支持的CSS框架');
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}
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break;
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}
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return errors;
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}
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}
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module.exports = new ConversionService();
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