Add logging and improve headers in file proxy preview

- Add console logging for debugging proxy preview requests
- Include filename in Content-Disposition header
- Add Content-Length header for proper response size
- Add X-Content-Type-Options header for PDF security
- Improve buffer handling clarity with explicit ArrayBuffer conversion

server/api/files/proxy-preview.ts

@@ -6,6 +6,8 @@ export default defineEventHandler(async (event) => {
     const query = getQuery(event);
     const fileName = query.fileName as string;
     
+    console.log('Proxy preview requested for:', fileName);
+    
     if (!fileName) {
       throw createError({
         statusCode: 400,
@@ -15,12 +17,15 @@ export default defineEventHandler(async (event) => {
     
     // Get content type
     const contentType = mime.lookup(fileName) || 'application/octet-stream';
+    console.log('Content type:', contentType);
     
     // Get the download URL
     const url = await getDownloadUrl(fileName);
+    console.log('MinIO URL obtained');
     
     // Fetch the file content from MinIO
     const response = await fetch(url);
+    console.log('MinIO response status:', response.status);
     
     if (!response.ok) {
       throw createError({
@@ -29,15 +34,26 @@ export default defineEventHandler(async (event) => {
       });
     }
     
-    // Get the file buffer
+    // Get the file data as ArrayBuffer
-    const buffer = Buffer.from(await response.arrayBuffer());
+    const arrayBuffer = await response.arrayBuffer();
+    const buffer = Buffer.from(arrayBuffer);
+    
+    console.log('File size:', buffer.length, 'bytes');
     
     // Set appropriate headers for preview
     setHeader(event, 'Content-Type', contentType);
-    setHeader(event, 'Content-Disposition', 'inline');
+    setHeader(event, 'Content-Disposition', `inline; filename="${fileName.split('/').pop()}"`);
     setHeader(event, 'Cache-Control', 'public, max-age=3600');
+    setHeader(event, 'Content-Length', String(buffer.length));
     
-    // Return the file buffer
+    // For PDF files, add additional headers
+    if (contentType === 'application/pdf') {
+      setHeader(event, 'X-Content-Type-Options', 'nosniff');
+    }
+    
+    console.log('Returning buffer for preview');
+    
+    // Return the buffer directly - Nitro will handle it properly
     return buffer;
   } catch (error: any) {
     console.error('Failed to proxy preview:', error);