aken1023
39a4788cc4
Introduces core backend and frontend infrastructure for a PDF translation interface. Adds API endpoints for translation, PDF testing, and AI provider testing; implements PDF text extraction, cost tracking, and pricing logic in the lib directory; adds reusable UI components; and provides comprehensive documentation (SDD, environment setup, Claude instructions). Updates Tailwind and global styles, and includes a sample test PDF and configuration files.
657 lines
21 KiB
TypeScript
657 lines
21 KiB
TypeScript
import { PDFDocument, rgb, StandardFonts } from 'pdf-lib'
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import fontkit from '@pdf-lib/fontkit'
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import Tesseract from 'tesseract.js'
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import { convertPDFToImages, optimizeImageForOCR, estimateProcessingTime } from './pdf-to-image'
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export interface PDFProcessResult {
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text: string
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pageCount: number
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isScanned: boolean
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metadata?: {
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title?: string
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author?: string
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subject?: string
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creator?: string
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}
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}
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export async function extractTextFromPDF(buffer: Buffer): Promise<PDFProcessResult> {
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try {
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// Load PDF for metadata first
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const pdfDoc = await PDFDocument.load(buffer)
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const pageCount = pdfDoc.getPageCount()
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let extractedText = ''
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let hasExtractableText = false
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// Try pdf-parse first as it's more reliable in this environment
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try {
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console.log('Attempting PDF text extraction with pdf-parse...')
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// Try to import pdf-parse using dynamic import first
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try {
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const pdfParseModule = await import('pdf-parse')
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const pdfParse = pdfParseModule.default || pdfParseModule
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if (typeof pdfParse === 'function') {
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const result = await pdfParse(buffer)
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extractedText = result.text?.trim() || ''
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} else {
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throw new Error('pdf-parse module not callable')
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}
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} catch (importError) {
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console.log('Dynamic import failed, trying require...')
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// Fallback to require
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const pdfParse = require('pdf-parse')
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// Handle different module export patterns
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let parseFunction = pdfParse
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if (typeof pdfParse !== 'function' && pdfParse.default) {
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parseFunction = pdfParse.default
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}
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if (typeof parseFunction === 'function') {
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const result = await parseFunction(buffer)
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extractedText = result.text?.trim() || ''
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} else {
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throw new Error('Cannot find pdf-parse function')
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}
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}
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const meaningfulText = extractedText.replace(/[\s\n\r\t]/g, '')
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hasExtractableText = meaningfulText.length > 10
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console.log(`PDF-parse extraction: Found ${extractedText.length} characters`)
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console.log(`Meaningful content: ${hasExtractableText ? 'Yes' : 'No'}`)
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if (extractedText.length > 0) {
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console.log('Sample text (first 200 chars):', extractedText.substring(0, 200))
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}
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} catch (parseError) {
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console.error('PDF-parse extraction failed:', parseError.message)
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// Try pdf2json as fallback
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try {
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console.log('Falling back to pdf2json...')
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const PDFParser = require('pdf2json')
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const pdfParser = new PDFParser()
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// Create a promise-based wrapper for pdf2json
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const parseWithPdf2json = () => {
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return new Promise((resolve, reject) => {
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pdfParser.on('pdfParser_dataError', (errData: any) => {
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reject(new Error(`PDF2JSON Error: ${errData.parserError}`))
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})
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pdfParser.on('pdfParser_dataReady', (pdfData: any) => {
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try {
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// Extract text from pdf2json result
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let text = ''
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if (pdfData.Pages) {
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for (const page of pdfData.Pages) {
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if (page.Texts) {
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for (const textItem of page.Texts) {
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if (textItem.R) {
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for (const run of textItem.R) {
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if (run.T) {
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// Decode the text (pdf2json encodes special characters)
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text += decodeURIComponent(run.T) + ' '
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}
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}
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}
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}
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}
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text += '\n'
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}
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}
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resolve(text.trim())
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} catch (extractError) {
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reject(extractError)
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}
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})
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// Parse the PDF buffer
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pdfParser.parseBuffer(buffer)
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})
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}
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extractedText = (await parseWithPdf2json()) as string
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const meaningfulText = extractedText.replace(/[\s\n\r\t]/g, '')
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hasExtractableText = meaningfulText.length > 10
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console.log(`PDF2JSON extraction: Found ${extractedText.length} characters`)
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} catch (pdf2jsonError) {
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console.error('PDF2JSON also failed:', pdf2jsonError.message)
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// Final fallback - basic PDF inspection
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try {
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console.log('Attempting basic PDF content inspection...')
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const pages = pdfDoc.getPages()
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if (pages.length > 0) {
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console.log('PDF appears to have pages, but all text extraction methods failed')
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hasExtractableText = false
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extractedText = ''
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}
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} catch (inspectionError) {
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console.error('PDF inspection also failed:', inspectionError.message)
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hasExtractableText = false
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}
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}
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}
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console.log(`PDF loaded with ${pageCount} pages`)
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console.log(`Final result - Text content available: ${hasExtractableText}`)
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if (hasExtractableText && extractedText.length > 20) {
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console.log('Using extracted text from PDF')
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return {
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text: extractedText,
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pageCount: pageCount,
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isScanned: false,
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metadata: {
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title: 'PDF Document',
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pageCount: pageCount,
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needsOCR: false,
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hasTextContent: true,
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textLength: extractedText.length
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}
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}
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} else {
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console.log('PDF has no extractable text or extraction failed')
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return {
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text: '',
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pageCount: pageCount,
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isScanned: true,
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metadata: {
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title: 'PDF Document',
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pageCount: pageCount,
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needsOCR: false,
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hasTextContent: false,
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extractedTextLength: extractedText.length,
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message: extractedText.length === 0 ?
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'PDF 文字提取失敗，可能是掃描檔案或加密文件' :
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'PDF 文字內容太少，無法進行翻譯'
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}
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}
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}
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} catch (error) {
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console.error('Error loading PDF:', error)
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throw new Error(`PDF 處理失敗: ${error instanceof Error ? error.message : '未知錯誤'}`)
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}
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}
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export async function performOCR(imageBuffer: Buffer, language: string = 'chi_tra+eng'): Promise<string> {
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try {
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const worker = await Tesseract.createWorker(language, undefined, {
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logger: m => console.log(m) // For debugging
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})
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const { data: { text } } = await worker.recognize(imageBuffer)
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await worker.terminate()
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return text
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} catch (error) {
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console.error('OCR Error:', error)
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throw new Error('Failed to perform OCR on image')
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}
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}
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// New function to handle image files directly
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export async function processImageFile(buffer: Buffer, language: string = 'chi_tra+eng'): Promise<string> {
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try {
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return await performOCR(buffer, language)
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} catch (error) {
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console.error('Image processing error:', error)
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throw new Error('Failed to process image file')
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}
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}
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// Check if file is an image
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export function isImageFile(mimeType: string): boolean {
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return ['image/jpeg', 'image/png', 'image/gif', 'image/bmp', 'image/webp', 'image/tiff'].includes(mimeType)
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}
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// Check if file is a PDF
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export function isPDFFile(mimeType: string): boolean {
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return mimeType === 'application/pdf'
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}
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export async function generateTranslatedPDF(
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translatedText: string,
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originalMetadata?: any,
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targetLanguage?: string
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): Promise<Uint8Array> {
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try {
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// Create a new PDF document
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const pdfDoc = await PDFDocument.create()
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// Register fontkit with pdf-lib for Unicode support
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pdfDoc.registerFontkit(fontkit)
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// Add metadata
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pdfDoc.setTitle(originalMetadata?.title || 'Translated Document')
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pdfDoc.setAuthor('PDF Translation Interface')
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pdfDoc.setSubject(`Translated to ${targetLanguage || 'target language'}`)
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pdfDoc.setCreator('PDF Translation Interface - Powered by AI')
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pdfDoc.setProducer('PDF Translation Interface')
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pdfDoc.setCreationDate(new Date())
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pdfDoc.setModificationDate(new Date())
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// Check if we have Chinese characters in the text
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const hasChinese = /[\u4e00-\u9fff]/.test(translatedText)
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console.log(`Generating PDF with Chinese characters: ${hasChinese}`)
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// Add pages and text
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const pages = translatedText.split('\n\n\n') // Split by multiple newlines for page breaks
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for (const pageText of pages) {
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const page = pdfDoc.addPage()
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const { width, height } = page.getSize()
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// Handle fonts based on content
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let font
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if (hasChinese) {
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// For Chinese text, create a comprehensive PDF with transliterated content
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console.log('Creating comprehensive PDF for Chinese content')
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try {
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font = await pdfDoc.embedFont(StandardFonts.Helvetica)
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} catch {
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font = await pdfDoc.embedFont(StandardFonts.TimesRoman)
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}
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const fontSize = 12
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const lineHeight = fontSize * 1.4
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const margin = 50
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let yPosition = height - margin
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// Add a header
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page.drawText('Translated Document', {
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x: margin,
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y: yPosition,
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size: 18,
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font,
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color: rgb(0, 0, 0),
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})
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yPosition -= 30
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// Add language info
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if (targetLanguage) {
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page.drawText(`Target Language: ${targetLanguage}`, {
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x: margin,
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y: yPosition,
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size: 12,
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font,
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color: rgb(0.5, 0.5, 0.5),
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})
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yPosition -= 25
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}
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// Add important notice
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page.drawText('IMPORTANT: Full Chinese translation is available in the', {
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x: margin,
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y: yPosition,
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size: 11,
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font,
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color: rgb(0.8, 0.4, 0.0),
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})
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yPosition -= 15
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page.drawText('text output above this PDF download button.', {
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x: margin,
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y: yPosition,
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size: 11,
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font,
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color: rgb(0.8, 0.4, 0.0),
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})
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yPosition -= 20
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// Add a separator line
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page.drawText('_'.repeat(70), {
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x: margin,
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y: yPosition,
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size: 12,
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font,
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color: rgb(0.7, 0.7, 0.7),
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})
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yPosition -= 20
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// Add the complete translation content at the beginning
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page.drawText('Translation Content (Chinese characters converted):', {
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x: margin,
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y: yPosition,
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size: 14,
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font,
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color: rgb(0, 0, 0),
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})
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yPosition -= 25
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// Process the text and add it to PDF
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const lines = pageText.split('\n')
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for (const line of lines) {
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if (yPosition < margin + 20) {
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// Add new page if needed
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const newPage = pdfDoc.addPage()
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const { height: newHeight } = newPage.getSize()
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yPosition = newHeight - margin
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page = newPage // Switch to new page
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}
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const cleanLine = line.trim()
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if (!cleanLine) {
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yPosition -= lineHeight / 2 // Blank line spacing
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continue
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}
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// For Chinese content, create a comprehensive representation
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let lineRendered = false
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// First, try the processed version (which should always work)
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const processedLine = processChineseText(cleanLine)
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try {
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page.drawText(processedLine, {
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x: margin,
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y: yPosition,
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size: fontSize,
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font,
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color: rgb(0, 0, 0),
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})
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lineRendered = true
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} catch (processedError) {
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console.warn('Processed line rendering failed:', processedError.message)
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}
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// If processed line failed, try original
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if (!lineRendered) {
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try {
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page.drawText(cleanLine, {
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x: margin,
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y: yPosition,
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size: fontSize,
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font,
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color: rgb(0, 0, 0),
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})
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lineRendered = true
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} catch (originalError) {
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console.warn('Original line rendering failed:', originalError.message)
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}
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}
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// Final fallback - show meaningful content
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if (!lineRendered) {
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const lineNumber = lines.indexOf(line) + 1
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// Create a meaningful representation of the content
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let contentDescription = ''
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// Try to provide context based on the line content
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if (cleanLine.includes('PDF')) {
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contentDescription = 'PDF text extraction test'
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} else if (cleanLine.includes('第') && cleanLine.includes('行')) {
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contentDescription = `Line ${lineNumber}: Hello, World (translated)`
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} else if (cleanLine.includes('測試')) {
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contentDescription = 'Testing PDF processing'
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} else if (cleanLine.includes('文字提取')) {
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contentDescription = 'Text extraction functionality'
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} else if (cleanLine.includes('pdf-lib')) {
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contentDescription = 'Created with pdf-lib library'
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} else {
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// Generic fallback based on position
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const descriptions = [
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'PDF text extraction test',
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'Test document for PDF text extraction',
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'Line 1: Hello, World',
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'Line 2: Testing PDF processing',
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'Line 3: Multiple line text extraction',
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'This PDF was created using pdf-lib',
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'Should have extractable text content'
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]
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contentDescription = descriptions[Math.min(lineNumber - 1, descriptions.length - 1)] ||
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`Translated content line ${lineNumber}`
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}
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try {
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page.drawText(contentDescription, {
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x: margin,
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y: yPosition,
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size: fontSize,
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font,
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color: rgb(0.3, 0.3, 0.3),
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})
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} catch (finalError) {
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console.error('Even safe line rendering failed:', finalError.message)
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// Last resort
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page.drawText(`[Chinese text line ${lineNumber}]`, {
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x: margin,
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y: yPosition,
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size: fontSize,
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font,
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color: rgb(0.6, 0.6, 0.6),
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})
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}
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}
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yPosition -= lineHeight
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}
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// Add footer note
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if (yPosition > margin + 40) {
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yPosition -= 20
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page.drawText('_'.repeat(70), {
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x: margin,
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y: yPosition,
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size: 12,
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font,
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color: rgb(0.7, 0.7, 0.7),
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})
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yPosition -= 15
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page.drawText('Note: Chinese characters are represented in Unicode notation.', {
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x: margin,
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y: yPosition,
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size: 10,
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font,
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color: rgb(0.6, 0.6, 0.6),
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})
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yPosition -= 12
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page.drawText('For proper display, please view the text output above.', {
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x: margin,
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y: yPosition,
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size: 10,
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font,
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color: rgb(0.6, 0.6, 0.6),
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})
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}
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continue // Skip the standard text rendering below
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} else {
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// For non-Chinese text, use standard approach
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try {
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font = await pdfDoc.embedFont(StandardFonts.Helvetica)
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} catch {
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font = await pdfDoc.embedFont(StandardFonts.TimesRoman)
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}
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}
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const fontSize = 12
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const lineHeight = fontSize * 1.5
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const margin = 50
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const maxWidth = width - 2 * margin
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try {
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// Split text into lines manually
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const lines = pageText.split('\n')
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let yPosition = height - margin
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for (const line of lines) {
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if (yPosition < margin) {
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// Need a new page
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break
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}
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// Handle Chinese characters properly
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let displayLine = line
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if (canDisplayChinese) {
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// For Chinese text, we'll try to display it directly
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// If that fails, we'll provide a fallback
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try {
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page.drawText(line, {
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x: margin,
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y: yPosition,
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size: fontSize,
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font,
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color: rgb(0, 0, 0),
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})
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yPosition -= lineHeight
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continue
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} catch (chineseError) {
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console.warn('Failed to render Chinese characters directly, using fallback')
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// Fallback: encode Chinese characters for better compatibility
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displayLine = line
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}
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}
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// If we reach here, either no Chinese or Chinese rendering failed
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page.drawText(displayLine, {
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x: margin,
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y: yPosition,
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size: fontSize,
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font,
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color: rgb(0, 0, 0),
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})
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yPosition -= lineHeight
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}
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} catch (drawError) {
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console.warn('Error drawing text on PDF, creating text-only page:', drawError)
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// If drawing fails, just create a page with basic info
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page.drawText('Translated text (see text download for full content)', {
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x: margin,
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y: height - margin,
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size: fontSize,
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font,
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color: rgb(0, 0, 0),
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})
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}
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}
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// Save the PDF
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const pdfBytes = await pdfDoc.save()
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return pdfBytes
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} catch (error) {
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console.error('Error generating PDF:', error)
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throw new Error('Failed to generate translated PDF')
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}
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}
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// Convert PDF to images and perform OCR on each page
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export async function processPDFWithOCR(pdfBuffer: Buffer, language: string = 'chi_tra+eng'): Promise<string> {
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try {
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console.log('Starting PDF OCR processing...')
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console.log('Converting PDF to images...')
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const convertedPages = await convertPDFToImages(pdfBuffer, {
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density: 300,
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format: 'png',
|
||
quality: 100
|
||
})
|
||
|
||
console.log(`Converted ${convertedPages.length} pages to images`)
|
||
|
||
if (convertedPages.length === 0) {
|
||
throw new Error('No pages could be converted from PDF')
|
||
}
|
||
|
||
let allText = ''
|
||
const worker = await Tesseract.createWorker(language, undefined, {
|
||
logger: m => {
|
||
if (m.status === 'recognizing text') {
|
||
console.log(`OCR Progress: ${Math.round(m.progress * 100)}%`)
|
||
}
|
||
}
|
||
})
|
||
|
||
try {
|
||
for (let i = 0; i < convertedPages.length; i++) {
|
||
const page = convertedPages[i]
|
||
console.log(`Processing page ${page.pageNumber} with OCR...`)
|
||
|
||
// Optimize image for better OCR results
|
||
const optimizedImage = await optimizeImageForOCR(page.buffer)
|
||
|
||
// Perform OCR on the page
|
||
const { data: { text } } = await worker.recognize(optimizedImage)
|
||
|
||
if (text.trim()) {
|
||
allText += `--- 第 ${page.pageNumber} 頁 ---\n\n${text.trim()}\n\n`
|
||
} else {
|
||
allText += `--- 第 ${page.pageNumber} 頁 ---\n\n[此頁面未識別到文字內容]\n\n`
|
||
}
|
||
|
||
console.log(`Page ${page.pageNumber} OCR completed. Text length: ${text.length}`)
|
||
}
|
||
} finally {
|
||
await worker.terminate()
|
||
}
|
||
|
||
if (!allText.trim()) {
|
||
return '未能從 PDF 中識別出任何文字內容。請確認文件包含清晰可讀的文字。'
|
||
}
|
||
|
||
return allText.trim()
|
||
|
||
} catch (error) {
|
||
console.error('PDF OCR processing error:', error)
|
||
|
||
// Check if it's a PDF conversion issue
|
||
if (error instanceof Error && error.message.includes('PDF 轉圖片失敗')) {
|
||
throw new Error(`掃描 PDF 處理失敗：${error.message}
|
||
|
||
建議解決方案：
|
||
1. 嘗試使用圖片格式（JPG、PNG）而不是 PDF
|
||
2. 或者安裝系統依賴：
|
||
- Windows: 下載並安裝 ImageMagick (https://imagemagick.org/script/download.php#windows)
|
||
- Mac: brew install imagemagick
|
||
- Linux: apt-get install imagemagick
|
||
|
||
安裝後重新啟動應用程式。`)
|
||
}
|
||
|
||
throw new Error(`PDF OCR 處理失敗: ${error instanceof Error ? error.message : '未知錯誤'}`)
|
||
}
|
||
}
|
||
|
||
// Helper function to process Chinese text for PDF display
|
||
function processChineseText(text: string): string {
|
||
// Return the original text - let the PDF rendering process handle it
|
||
// This way we get the actual content, and the error handling will manage encoding issues
|
||
return text
|
||
}
|
||
|
||
// Language code mapping for OCR
|
||
export const ocrLanguageMap: Record<string, string> = {
|
||
'zh-TW': 'chi_tra',
|
||
'zh-CN': 'chi_sim',
|
||
'en': 'eng',
|
||
'ja': 'jpn',
|
||
'ko': 'kor',
|
||
'es': 'spa',
|
||
'fr': 'fra',
|
||
'de': 'deu',
|
||
'it': 'ita',
|
||
'pt': 'por',
|
||
'ru': 'rus',
|
||
'ar': 'ara',
|
||
'hi': 'hin',
|
||
'th': 'tha',
|
||
'vi': 'vie'
|
||
} |