Use actual MIME type for trust center file exports

The export endpoint was hardcoding application/pdf for all trust center
files. Now the real MIME type from the stored file metadata is threaded
through the service layer and returned as a data URI, so non-PDF files
are handled correctly on the frontend. Watermarking is only applied when
the file is actually a PDF.

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

apps/trust/src/pages/DocumentPage.tsx

@@ -164,8 +164,19 @@ type Props = {
   queryRef: PreloadedQuery<DocumentPageQueryType>;
 };
 
-function isPdfFilename(name: string): boolean {
-  return name.toLowerCase().endsWith(".pdf");
+function isPdfDataUri(dataUri: string): boolean {
+  return dataUri.startsWith("data:application/pdf;");
+}
+
+function extractBase64Data(dataUri: string): string {
+  const commaIndex = dataUri.indexOf(",");
+  if (commaIndex === -1) return dataUri;
+  return dataUri.substring(commaIndex + 1);
+}
+
+function extractMimeType(dataUri: string): string {
+  const match = dataUri.match(/^data:([^;]+);/);
+  return match?.[1] ?? "application/octet-stream";
 }
 
 function getNodeTitle(node: DocumentPageQueryType["response"]["node"]): string | undefined {
@@ -276,7 +287,7 @@ export function DocumentPage({ queryRef }: Props) {
           variables: { input: { trustCenterFileId: node.id } },
           onCompleted: (response, errors) => {
             if (onCompletedErrors(errors)) return;
-            if (isPdfFilename(node.name)) {
+            if (isPdfDataUri(response.exportTrustCenterFile.data)) {
               setPdfData(response.exportTrustCenterFile.data);
             } else {
               setFileData(response.exportTrustCenterFile.data);
@@ -359,16 +370,18 @@ export function DocumentPage({ queryRef }: Props) {
 
   const isRequesting = isRequestingAccess || isRequestingFileAccess || isRequestingReportAccess;
   const hasRequested = node.access?.status === "REQUESTED";
-  const isPdf = node.__typename === "Document" || node.__typename === "Report" || (node.__typename === "TrustCenterFile" && isPdfFilename(node.name));
+  const isPdf = node.__typename === "Document" || node.__typename === "Report" || (node.__typename === "TrustCenterFile" && pdfData !== null);
 
   const handleDownload = () => {
     if (!fileData || !nodeTitle) return;
-    const byteCharacters = atob(fileData);
+    const base64 = extractBase64Data(fileData);
+    const mimeType = extractMimeType(fileData);
+    const byteCharacters = atob(base64);
     const byteNumbers = new Uint8Array(byteCharacters.length);
     for (let i = 0; i < byteCharacters.length; i++) {
       byteNumbers[i] = byteCharacters.charCodeAt(i);
     }
-    const blob = new Blob([byteNumbers]);
+    const blob = new Blob([byteNumbers], { type: mimeType });
     const url = URL.createObjectURL(blob);
     const a = document.createElement("a");
     a.href = url;

pkg/server/api/trust/v1/v1_resolver.go

@@ -490,14 +490,14 @@ func (r *mutationResolver) ExportTrustCenterFile(ctx context.Context, input type
 	}
 
 	if trustCenterFile.TrustCenterVisibility == coredata.TrustCenterVisibilityPublic {
-		fileData, err := trustService.TrustCenterFiles.ExportFileWithoutWatermark(ctx, input.TrustCenterFileID)
+		fileData, mimeType, err := trustService.TrustCenterFiles.ExportFileWithoutWatermark(ctx, input.TrustCenterFileID)
 		if err != nil {
 			r.logger.ErrorCtx(ctx, "cannot export trust center file", log.Error(err))
 			return nil, gqlutils.Internal(ctx)
 		}
 
 		return &types.ExportTrustCenterFilePayload{
-			Data: fmt.Sprintf("data:application/pdf;base64,%s", base64.StdEncoding.EncodeToString(fileData)),
+			Data: fmt.Sprintf("data:%s;base64,%s", mimeType, base64.StdEncoding.EncodeToString(fileData)),
 		}, nil
 	}
 
@@ -519,14 +519,14 @@ func (r *mutationResolver) ExportTrustCenterFile(ctx context.Context, input type
 		return nil, gqlutils.Forbiddenf(ctx, "access denied: no permission to access this file")
 	}
 
-	fileData, err := trustService.TrustCenterFiles.ExportFile(ctx, input.TrustCenterFileID, identity.EmailAddress)
+	fileData, mimeType, err := trustService.TrustCenterFiles.ExportFile(ctx, input.TrustCenterFileID, identity.EmailAddress)
 	if err != nil {
 		r.logger.ErrorCtx(ctx, "cannot export trust center file", log.Error(err))
 		return nil, gqlutils.Internal(ctx)
 	}
 
 	return &types.ExportTrustCenterFilePayload{
-		Data: fmt.Sprintf("data:application/pdf;base64,%s", base64.StdEncoding.EncodeToString(fileData)),
+		Data: fmt.Sprintf("data:%s;base64,%s", mimeType, base64.StdEncoding.EncodeToString(fileData)),
 	}, nil
 }
 

pkg/trust/trust_center_file_service.go

@@ -97,31 +97,34 @@ func (s *TrustCenterFileService) ExportFile(
 	ctx context.Context,
 	trustCenterFileID gid.GID,
 	email mail.Addr,
-) ([]byte, error) {
-	pdfData, err := s.exportFileData(ctx, trustCenterFileID)
+) ([]byte, string, error) {
+	fileData, mimeType, err := s.exportFileData(ctx, trustCenterFileID)
 	if err != nil {
-		return nil, fmt.Errorf("cannot export trust center file: %w", err)
+		return nil, "", fmt.Errorf("cannot export trust center file: %w", err)
 	}
 
-	watermarkedPDF, err := watermarkpdf.AddConfidentialWithTimestamp(pdfData, email)
-	if err != nil {
-		return nil, fmt.Errorf("cannot add watermark to PDF: %w", err)
+	if mimeType == "application/pdf" {
+		watermarkedPDF, err := watermarkpdf.AddConfidentialWithTimestamp(fileData, email)
+		if err != nil {
+			return nil, "", fmt.Errorf("cannot add watermark to PDF: %w", err)
+		}
+		return watermarkedPDF, mimeType, nil
 	}
 
-	return watermarkedPDF, nil
+	return fileData, mimeType, nil
 }
 
 func (s *TrustCenterFileService) ExportFileWithoutWatermark(
 	ctx context.Context,
 	trustCenterFileID gid.GID,
-) ([]byte, error) {
+) ([]byte, string, error) {
 	return s.exportFileData(ctx, trustCenterFileID)
 }
 
 func (s *TrustCenterFileService) exportFileData(
 	ctx context.Context,
 	trustCenterFileID gid.GID,
-) ([]byte, error) {
+) ([]byte, string, error) {
 	var trustCenterFile *coredata.TrustCenterFile
 	var file *coredata.File
 
@@ -139,7 +142,7 @@ func (s *TrustCenterFileService) exportFileData(
 		return nil
 	})
 	if err != nil {
-		return nil, err
+		return nil, "", err
 	}
 
 	result, err := s.svc.s3.GetObject(ctx, &s3.GetObjectInput{
@@ -147,14 +150,14 @@ func (s *TrustCenterFileService) exportFileData(
 		Key:    new(file.FileKey),
 	})
 	if err != nil {
-		return nil, fmt.Errorf("cannot download file from S3: %w", err)
+		return nil, "", fmt.Errorf("cannot download file from S3: %w", err)
 	}
 	defer func() { _ = result.Body.Close() }()
 
 	fileData, err := io.ReadAll(result.Body)
 	if err != nil {
-		return nil, fmt.Errorf("cannot read file data: %w", err)
+		return nil, "", fmt.Errorf("cannot read file data: %w", err)
 	}
 
-	return fileData, nil
+	return fileData, file.MimeType, nil
 }