first commit

2026-04-20 16:18:26 +08:00
commit 51d794376c
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+const { PDFDocument } = require('pdf-lib');
+const fs = require('fs');
+const path = require('path');
+
+/**
+ * Extracts the first two pages of a PDF and saves them as a new PDF file.
+ * We do this instead of backend image conversion because Node Canvas fails 
+ * compilation on Windows 10/Node 24 environments without Visual Studio. 
+ * The client will smoothly render this secure 2-page PDF into an image via Canvas.
+ */
+async function extractFirstTwoPages(inputPath, outputPath) {
+  try {
+    const existingPdfBytes = fs.readFileSync(inputPath);
+    const pdfDoc = await PDFDocument.load(existingPdfBytes);
+    
+    // Create a new document
+    const newPdf = await PDFDocument.create();
+    
+    // Determine how many pages to copy (max 2)
+    const pageCount = pdfDoc.getPageCount();
+    const pagesToCopy = Math.min(pageCount, 2);
+    
+    const pageIndices = Array.from({ length: pagesToCopy }, (_, i) => i);
+    
+    if (pageIndices.length > 0) {
+      const copiedPages = await newPdf.copyPages(pdfDoc, pageIndices);
+      copiedPages.forEach((page) => newPdf.addPage(page));
+    }
+    
+    const newPdfBytes = await newPdf.save();
+    fs.writeFileSync(outputPath, newPdfBytes);
+    
+    return true;
+  } catch (error) {
+    console.error('Error processing PDF:', error);
+    throw error;
+  }
+}
+
+module.exports = {
+  extractFirstTwoPages
+};