GC: Use PackFile to de-dup logic

GC has several places where it tries to build files names for packs that
we can use the PackFile class for instead.

Change-Id: I99e5ceff9050f8583368fca35279251955e4644d
Signed-off-by: Nasser Grainawi <quic_nasserg@quicinc.com>

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java

 				if (shouldLoosen) {
 					loosen(inserter, reader, oldPack, ids);
 				}
-				prunePack(oldName);
+				prunePack(oldPack.getPackFile());
 			}
 		}
 
 	 * moves the pack file to the preserved directory
 	 *
 	 * @param packFile
-	 * @param packName
-	 * @param ext
 	 * @param deleteOptions
 	 * @throws IOException
 	 */
-	private void removeOldPack(File packFile, String packName, PackExt ext,
-			int deleteOptions) throws IOException {
+	private void removeOldPack(PackFile packFile, int deleteOptions)
+			throws IOException {
 		if (pconfig.isPreserveOldPacks()) {
 			File oldPackDir = repo.getObjectDatabase().getPreservedDirectory();
 			FileUtils.mkdir(oldPackDir, true);
 
-			String oldPackName = "pack-" + packName + ".old-" + ext.getExtension();  //$NON-NLS-1$ //$NON-NLS-2$
-			File oldPackFile = new File(oldPackDir, oldPackName);
+			PackFile oldPackFile = packFile
+					.createPreservedForDirectory(oldPackDir);
 			FileUtils.rename(packFile, oldPackFile);
 		} else {
 			FileUtils.delete(packFile, deleteOptions);
 	 * ".index" file and when failing to delete the ".pack" file we are left
 	 * with a ".pack" file without a ".index" file.
 	 *
-	 * @param packName
+	 * @param packFile
 	 */
-	private void prunePack(String packName) {
-		PackExt[] extensions = PackExt.values();
+	private void prunePack(PackFile packFile) {
 		try {
 			// Delete the .pack file first and if this fails give up on deleting
 			// the other files
 			int deleteOptions = FileUtils.RETRY | FileUtils.SKIP_MISSING;
-			for (PackExt ext : extensions)
-				if (PackExt.PACK.equals(ext)) {
-					File f = nameFor(packName, "." + ext.getExtension()); //$NON-NLS-1$
-					removeOldPack(f, packName, ext, deleteOptions);
-					break;
-				}
+			removeOldPack(packFile.create(PackExt.PACK), deleteOptions);
+
 			// The .pack file has been deleted. Delete as many as the other
 			// files as you can.
 			deleteOptions |= FileUtils.IGNORE_ERRORS;
-			for (PackExt ext : extensions) {
+			for (PackExt ext : PackExt.values()) {
 				if (!PackExt.PACK.equals(ext)) {
-					File f = nameFor(packName, "." + ext.getExtension()); //$NON-NLS-1$
-					removeOldPack(f, packName, ext, deleteOptions);
+					removeOldPack(packFile.create(ext), deleteOptions);
 				}
 			}
 		} catch (IOException e) {
 			}
 
 			// rename the temporary files to real files
-			File realPack = nameFor(id, ".pack"); //$NON-NLS-1$
+			File realPack = nameFor(id, PackExt.PACK);
 
 			repo.getObjectDatabase().closeAllPackHandles(realPack);
 			tmpPack.setReadOnly();
 				File tmpExt = tmpEntry.getValue();
 				tmpExt.setReadOnly();
 
-				File realExt = nameFor(id,
-						"." + tmpEntry.getKey().getExtension()); //$NON-NLS-1$
+				File realExt = nameFor(id, tmpEntry.getKey());
 				try {
 					FileUtils.rename(tmpExt, realExt,
 							StandardCopyOption.ATOMIC_MOVE);
 		}
 	}
 
-	private File nameFor(String name, String ext) {
-		File packdir = repo.getObjectDatabase().getPackDirectory();
-		return new File(packdir, "pack-" + name + ext); //$NON-NLS-1$
+	private PackFile nameFor(String name, PackExt ext) {
+		return new PackFile(repo.getObjectDatabase().getPackDirectory(),
+				"pack-" + name).create(ext); //$NON-NLS-1$
 	}
 
 	private void checkCancelled() throws CancelledException {