perf(core): Stream responses and unify temp file lifecycle across controllers (#4330)

app/common/src/main/java/stirling/software/common/util/PDFService.java

@@ -0,0 +1,35 @@
+package stirling.software.common.util;
+
+import java.io.IOException;
+import java.util.List;
+
+import org.apache.pdfbox.multipdf.PDFMergerUtility;
+import org.apache.pdfbox.pdmodel.PDDocument;
+import org.springframework.stereotype.Service;
+
+import lombok.RequiredArgsConstructor;
+
+import stirling.software.common.service.CustomPDFDocumentFactory;
+
+@Service
+@RequiredArgsConstructor
+public class PDFService {
+
+    private final CustomPDFDocumentFactory pdfDocumentFactory;
+
+    /*
+     * Merge multiple PDF documents into a single PDF document
+     *
+     * @param documents List of PDDocument to be merged
+     * @return Merged PDDocument
+     * @throws IOException If an error occurs during merging
+     */
+    public PDDocument mergeDocuments(List<PDDocument> documents) throws IOException {
+        PDDocument merged = pdfDocumentFactory.createNewDocument();
+        PDFMergerUtility merger = new PDFMergerUtility();
+        for (PDDocument doc : documents) {
+            merger.appendDocument(merged, doc);
+        }
+        return merged;
+    }
+}

app/common/src/main/java/stirling/software/common/util/WebResponseUtils.java

@@ -4,6 +4,8 @@ import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.net.URLEncoder;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
 
 import org.apache.pdfbox.pdmodel.PDDocument;
 import org.springframework.http.HttpHeaders;
@@ -11,9 +13,13 @@ import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.multipart.MultipartFile;
+import org.springframework.web.servlet.mvc.method.annotation.StreamingResponseBody;
 
 import io.github.pixee.security.Filenames;
 
+import lombok.extern.slf4j.Slf4j;
+
+@Slf4j
 public class WebResponseUtils {
 
     public static ResponseEntity<byte[]> baosToWebResponse(
@@ -64,4 +70,59 @@ public class WebResponseUtils {
 
         return baosToWebResponse(baos, docName);
     }
+
+    /**
+     * Convert a File to a web response (PDF default).
+     *
+     * @param outputTempFile The temporary file to be sent as a response.
+     * @param docName The name of the document.
+     * @return A ResponseEntity containing the file as a resource.
+     */
+    public static ResponseEntity<StreamingResponseBody> pdfFileToWebResponse(
+            TempFile outputTempFile, String docName) throws IOException {
+        return fileToWebResponse(outputTempFile, docName, MediaType.APPLICATION_PDF);
+    }
+
+    /**
+     * Convert a File to a web response (ZIP default).
+     *
+     * @param outputTempFile The temporary file to be sent as a response.
+     * @param docName The name of the document.
+     * @return A ResponseEntity containing the file as a resource.
+     */
+    public static ResponseEntity<StreamingResponseBody> zipFileToWebResponse(
+            TempFile outputTempFile, String docName) throws IOException {
+        return fileToWebResponse(outputTempFile, docName, MediaType.APPLICATION_OCTET_STREAM);
+    }
+
+    /**
+     * Convert a File to a web response with explicit media type (e.g., ZIP).
+     *
+     * @param outputTempFile The temporary file to be sent as a response.
+     * @param docName The name of the document.
+     * @param mediaType The content type to set on the response.
+     * @return A ResponseEntity containing the file as a resource.
+     */
+    public static ResponseEntity<StreamingResponseBody> fileToWebResponse(
+            TempFile outputTempFile, String docName, MediaType mediaType) throws IOException {
+
+        Path path = outputTempFile.getFile().toPath().normalize();
+        long len = Files.size(path);
+        HttpHeaders headers = new HttpHeaders();
+        headers.setContentType(mediaType);
+        headers.setContentLength(len);
+        headers.add(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + docName + "\"");
+
+        StreamingResponseBody body =
+                os -> {
+                    try (os) {
+                        Files.copy(path, os);
+                        os.flush();
+                    } finally {
+                        outputTempFile.close();
+                    }
+                };
+
+        return new ResponseEntity<>(body, headers, HttpStatus.OK);
+    }
 }