Correcting Repackaging of zip file

src/main/java/at/ac/uibk/gitsearch/service/ShoppingBasketService.java

 package at.ac.uibk.gitsearch.service;
 
+import java.io.FileOutputStream;
+import java.io.IOException;
 import java.io.InputStream;
+import java.io.PipedInputStream;
+import java.io.PipedOutputStream;
+import java.nio.file.Path;
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
 import java.util.UUID;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipInputStream;
+import java.util.zip.ZipOutputStream;
 
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.codeability.sharing.plugins.api.ShoppingBasket;
@@ -18,6 +26,8 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
+import org.springframework.util.StreamUtils;
+import org.springframework.util.StringUtils;
 
 import com.google.common.cache.CacheBuilder;
 import com.google.common.cache.CacheLoader;
@@ -242,11 +252,62 @@ public class ShoppingBasketService {
 		return ex;
 	}
 	
-	public InputStream getRepositoryZip(String basketToken, int position) throws GitLabApiException {
+	public InputStream getRepositoryZip(String basketToken, int position) throws GitLabApiException, IOException {
 		final @Nullable ExtendedShoppingBasket basketInfo = basketCache.getIfPresent(basketToken);
 		ShoppingBasket basket = getBasket( basketToken);
         final GitLabApi gitLabApi = basketInfo==null?gitLabRepository.getGitLabApi(Optional.empty()):gitLabRepository.getGitLabApi(basketInfo.getGitLabAccessInfo());
-		return gitLabApi.getRepositoryApi().getRepositoryArchive(basket.exerciseInfo[position].gitLabProjectId, "HEAD", "zip");
+		return rePackageGitLabProjectZip(new ZipInputStream(gitLabApi.getRepositoryApi().getRepositoryArchive(basket.exerciseInfo[position].gitLabProjectId, "HEAD", "zip")), "from project " + basket.exerciseInfo[position].gitLabProjectId);
+	}
+	
+	/**
+	 * chops of the main folder, and brings every file one level up. Also deleting
+	 * all plain files in main folder.
+	 * 
+	 * @param zipIn the zip to be repackaged
+	 * @param originalLocation the original location. For debug purposes only.
+	 * @return
+	 * @throws IOException
+	 */
+	protected InputStream rePackageGitLabProjectZip(ZipInputStream zipIn, String originalLocation) throws IOException {
+		final PipedInputStream pis = new PipedInputStream(1024*256);
+		final PipedOutputStream pos = new PipedOutputStream(pis);
+
+		Runnable rePackage = () -> {
+			try (ZipOutputStream zipOut = new ZipOutputStream(pos)) {
+
+				ZipEntry zipInEntry = zipIn.getNextEntry();
+				String prefix = "";
+				if (zipInEntry.isDirectory()) { // main directory is prefix to all entries
+					prefix = zipInEntry.getName();
+				}
+
+				while (zipInEntry != null) {
+					if (zipInEntry.getName().startsWith(prefix)) {
+						String newName = zipInEntry.getName().substring(prefix.length());
+						if (!StringUtils.isEmpty(newName)) {
+							ZipEntry zipOutEntry = new ZipEntry(newName);
+							if (zipInEntry.isDirectory()) {
+//							log.debug("ignoring directory {}", zipInEntry.getName());
+								zipOut.putNextEntry(zipOutEntry);
+							} else {
+								zipOut.putNextEntry(zipOutEntry);
+								StreamUtils.copy(zipIn, zipOut);
+								zipOut.closeEntry();
+							}
+						}}
+					zipInEntry = zipIn.getNextEntry();
+				}
+				zipIn.close();
+				zipOut.close();
+			} catch (IOException e) {
+				log.error("Cannot rezip file from {}", originalLocation);
+			}
+		};
+
+		new Thread(rePackage).start();
+
+		return pis;
+
 	}
 	
 	public final static Duration BASKET_EXPIRY_INTERVAL = Duration.ofMinutes(10);

src/test/java/at/ac/uibk/gitsearch/service/ShoppingBasketServiceIT.java

+package at.ac.uibk.gitsearch.service;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipInputStream;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import at.ac.uibk.gitsearch.GitsearchApp;
+
+@SpringBootTest(classes = GitsearchApp.class)
+public class ShoppingBasketServiceIT {
+	
+	private static final String TEST_ZIP_LOCATION = "at/ac/uibk/gitsearch/service/testData/junit-quality-tests-exercise-master.zip";
+	@Autowired
+	protected ShoppingBasketService shoppingBasketService;
+	
+	private final Logger log = LoggerFactory.getLogger(ShoppingBasketServiceIT.class);
+	
+    @Test
+	public void testRepackage() throws IOException {
+		
+		final InputStream resourceStream = this.getClass().getClassLoader().getResourceAsStream(TEST_ZIP_LOCATION);
+
+		final ZipInputStream testZip = new ZipInputStream(resourceStream);
+		
+		final InputStream testRepackagedZipIS = shoppingBasketService.rePackageGitLabProjectZip(testZip, "from " + TEST_ZIP_LOCATION);
+
+		final ZipInputStream testRepackagedZip = new ZipInputStream(testRepackagedZipIS);
+		
+		ZipEntry entry = testRepackagedZip.getNextEntry();
+		
+		while(entry!=null) {
+			log.info("found entry {} (directory: {})", entry.getName(), entry.isDirectory());
+			Assert.assertTrue("original folder not chopped off?", !entry.getName().startsWith("junit-quality-tests-exercise-master"));
+			entry = testRepackagedZip.getNextEntry();
+		}
+		
+		testRepackagedZip.close();
+	}
+	
+
+}