Add React-based remove annotations tool (#4504)

Co-authored-by: Claude <[email protected]>

frontend/src/hooks/tools/removeAnnotations/useRemoveAnnotationsOperation.ts

@@ -0,0 +1,99 @@
+import { useTranslation } from 'react-i18next';
+import { useToolOperation, ToolType } from '../shared/useToolOperation';
+import { createStandardErrorHandler } from '../../../utils/toolErrorHandler';
+import { RemoveAnnotationsParameters, defaultParameters } from './useRemoveAnnotationsParameters';
+
+// Client-side PDF processing using PDF-lib
+const removeAnnotationsProcessor = async (_parameters: RemoveAnnotationsParameters, files: File[]): Promise<File[]> => {
+  // Dynamic import of PDF-lib for client-side processing
+  const { PDFDocument, PDFName, PDFRef, PDFDict } = await import('pdf-lib');
+
+  const processedFiles: File[] = [];
+
+  for (const file of files) {
+    try {
+      // Load the PDF
+      const fileArrayBuffer = await file.arrayBuffer();
+      const pdfBytesIn = new Uint8Array(fileArrayBuffer);
+      const pdfDoc = await PDFDocument.load(pdfBytesIn, { ignoreEncryption: true });
+      const ctx = pdfDoc.context;
+
+      const pages = pdfDoc.getPages();
+      for (let i = 0; i < pages.length; i++) {
+        const page = pages[i];
+
+        // Annots() returns PDFArray | undefined
+        const annots = page.node.Annots();
+        if (!annots || annots.size() === 0) continue;
+
+        // Delete each annotation object (they are usually PDFRef)
+        for (let j = annots.size() - 1; j >= 0; j--) {
+          try {
+            const entry = annots.get(j);
+            if (entry instanceof PDFRef) {
+              ctx.delete(entry);
+            } else if (entry instanceof PDFDict) {
+              // In practice, Annots array should contain refs; if not, just remove the array linkage.
+              // (We avoid poking internal maps to find a ref for the dict.)
+            }
+          } catch (err) {
+            console.warn(`Failed to remove annotation ${j} on page ${i + 1}:`, err);
+          }
+        }
+
+        // Remove the Annots key entirely
+        try {
+          if (page.node.has(PDFName.of('Annots'))) {
+            page.node.delete(PDFName.of('Annots'));
+          }
+        } catch (err) {
+          console.warn(`Failed to delete /Annots on page ${i + 1}:`, err);
+        }
+      }
+
+      // Optional: if removing ALL annotations across the doc, strip AcroForm to avoid dangling widget refs
+      try {
+        const catalog = pdfDoc.context.lookup(pdfDoc.context.trailerInfo.Root);
+        if (catalog && 'has' in catalog && 'delete' in catalog) {
+          const catalogDict = catalog as any;
+          if (catalogDict.has(PDFName.of('AcroForm'))) {
+            catalogDict.delete(PDFName.of('AcroForm'));
+          }
+        }
+      } catch (err) {
+        console.warn('Failed to remove /AcroForm:', err);
+      }
+
+      // Save returns Uint8Array — safe for Blob
+      const outBytes = await pdfDoc.save();
+      const outBlob = new Blob([new Uint8Array(outBytes)], { type: 'application/pdf' });
+
+      // Create new file with original name
+      const processedFile = new File([outBlob], file.name, { type: 'application/pdf' });
+
+      processedFiles.push(processedFile);
+    } catch (error) {
+      console.error('Error processing file:', file.name, error);
+      throw new Error(`Failed to process ${file.name}: ${error instanceof Error ? error.message : 'Unknown error'}`);
+    }
+  }
+
+  return processedFiles;
+};
+
+// Static configuration object
+export const removeAnnotationsOperationConfig = {
+  toolType: ToolType.custom,
+  operationType: 'removeAnnotations',
+  customProcessor: removeAnnotationsProcessor,
+  defaultParameters,
+} as const;
+
+export const useRemoveAnnotationsOperation = () => {
+  const { t } = useTranslation();
+
+  return useToolOperation<RemoveAnnotationsParameters>({
+    ...removeAnnotationsOperationConfig,
+    getErrorMessage: createStandardErrorHandler(t('removeAnnotations.error.failed', 'An error occurred while removing annotations from the PDF.'))
+  });
+};