fix gzip filter on resteasy 3.6.2

scm-core/src/main/java/sonia/scm/filter/GZipResponseFilter.java

@@ -1,24 +1,50 @@
 package sonia.scm.filter;
 
-import lombok.extern.slf4j.Slf4j;
-import sonia.scm.util.WebUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
-import javax.ws.rs.container.ContainerRequestContext;
-import javax.ws.rs.container.ContainerResponseContext;
-import javax.ws.rs.container.ContainerResponseFilter;
+import javax.ws.rs.WebApplicationException;
+import javax.ws.rs.core.HttpHeaders;
 import javax.ws.rs.ext.Provider;
+import javax.ws.rs.ext.WriterInterceptor;
+import javax.ws.rs.ext.WriterInterceptorContext;
 import java.io.IOException;
+import java.io.OutputStream;
+import java.util.Locale;
 import java.util.zip.GZIPOutputStream;
 
 @Provider
-@Slf4j
-public class GZipResponseFilter implements ContainerResponseFilter {
-  public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) throws IOException {
-    if (WebUtil.isGzipSupported(requestContext::getHeaderString)) {
-      log.trace("compress output with gzip");
-      GZIPOutputStream wrappedResponse = new GZIPOutputStream(responseContext.getEntityStream());
-      responseContext.getHeaders().add("Content-Encoding", "gzip");
-      responseContext.setEntityStream(wrappedResponse);
+public class GZipResponseFilter implements WriterInterceptor {
+
+  private static final Logger LOG = LoggerFactory.getLogger(GZipResponseFilter.class);
+
+  @Override
+  public void aroundWriteTo(WriterInterceptorContext context) throws IOException, WebApplicationException {
+    if (isGZipSupported(context)) {
+      LOG.trace("compress output with gzip");
+      encodeWithGZip(context);
+    } else {
+      context.proceed();
     }
   }
+
+  private void encodeWithGZip(WriterInterceptorContext context) throws IOException {
+    context.getHeaders().remove(HttpHeaders.CONTENT_LENGTH);
+    context.getHeaders().add(HttpHeaders.CONTENT_ENCODING, "gzip");
+
+    OutputStream outputStream = context.getOutputStream();
+    GZIPOutputStream compressedOutputStream = new GZIPOutputStream(outputStream);
+    context.setOutputStream(compressedOutputStream);
+    try {
+      context.proceed();
+    } finally {
+      compressedOutputStream.finish();
+      context.setOutputStream(outputStream);
+    }
+  }
+
+  private boolean isGZipSupported(WriterInterceptorContext context) {
+    Object encoding = context.getHeaders().getFirst(HttpHeaders.ACCEPT_ENCODING);
+    return encoding != null && encoding.toString().toLowerCase(Locale.ENGLISH).contains("gzip");
+  }
 }

scm-core/src/test/java/sonia/scm/filter/GZipResponseFilterTest.java

@@ -0,0 +1,81 @@
+package sonia.scm.filter;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import javax.ws.rs.core.HttpHeaders;
+import javax.ws.rs.core.MultivaluedMap;
+import javax.ws.rs.ext.WriterInterceptorContext;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.zip.GZIPOutputStream;
+
+import static org.mockito.Mockito.*;
+
+@ExtendWith(MockitoExtension.class)
+class GZipResponseFilterTest {
+
+  @Mock
+  private WriterInterceptorContext context;
+
+  @Mock
+  private MultivaluedMap<String,Object> headers;
+
+  private final GZipResponseFilter filter = new GZipResponseFilter();
+
+  @BeforeEach
+  void setUpContext() {
+    when(context.getHeaders()).thenReturn(headers);
+  }
+
+  @Test
+  void shouldSkipGZipCompression() throws IOException {
+    when(headers.getFirst(HttpHeaders.ACCEPT_ENCODING)).thenReturn("deflate, br");
+
+    filter.aroundWriteTo(context);
+
+    verifySkipped();
+  }
+
+  @Test
+  void shouldSkipGZipCompressionWithoutAcceptEncodingHeader() throws IOException {
+    filter.aroundWriteTo(context);
+
+    verifySkipped();
+  }
+
+  private void verifySkipped() throws IOException {
+    verify(context, never()).getOutputStream();
+    verify(context).proceed();
+  }
+
+
+  @Nested
+  class AcceptGZipEncoding {
+
+    @BeforeEach
+    void setUpContext() {
+      when(headers.getFirst(HttpHeaders.ACCEPT_ENCODING)).thenReturn("gzip, deflate, br");
+      when(context.getOutputStream()).thenReturn(new ByteArrayOutputStream());
+    }
+
+    @Test
+    void shouldEncode() throws IOException {
+      filter.aroundWriteTo(context);
+
+      verify(headers).remove(HttpHeaders.CONTENT_LENGTH);
+      verify(headers).add(HttpHeaders.CONTENT_ENCODING, "gzip");
+
+      verify(context).setOutputStream(any(GZIPOutputStream.class));
+      verify(context, times(2)).setOutputStream(any(OutputStream.class));
+    }
+
+  }
+
+
+}