/*
    * Copyright (C) 2009-2010, Google Inc.
    * Copyright (C) 2009, Robin Rosenberg <robin.rosenberg@dewire.com> and others
    *
    * This program and the accompanying materials are made available under the
    * terms of the Eclipse Distribution License v. 1.0 which is available at
    * https://www.eclipse.org/org/documents/edl-v10.php.
    *
    * SPDX-License-Identifier: BSD-3-Clause
   */
  
  package org.eclipse.jgit.internal.storage.file;
  
  import static org.junit.Assert.assertArrayEquals;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertFalse;
  import static org.junit.Assert.assertNotNull;
  import static org.junit.Assert.assertNotSame;
  import static org.junit.Assert.fail;
  
  import java.io.BufferedOutputStream;
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.time.Instant;
  
  import org.eclipse.jgit.errors.IncorrectObjectTypeException;
  import org.eclipse.jgit.errors.MissingObjectException;
  import org.eclipse.jgit.internal.storage.pack.PackWriter;
  import org.eclipse.jgit.junit.RepositoryTestCase;
  import org.eclipse.jgit.lib.AnyObjectId;
  import org.eclipse.jgit.lib.Constants;
  import org.eclipse.jgit.lib.NullProgressMonitor;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.ObjectInserter;
  import org.eclipse.jgit.lib.ObjectLoader;
  import org.eclipse.jgit.lib.Repository;
  import org.eclipse.jgit.revwalk.RevObject;
  import org.eclipse.jgit.revwalk.RevWalk;
  import org.eclipse.jgit.storage.file.WindowCacheConfig;
  import org.eclipse.jgit.util.FS;
  import org.eclipse.jgit.util.FileUtils;
  import org.junit.After;
  import org.junit.Before;
  import org.junit.Test;
  
  public class ConcurrentRepackTest extends RepositoryTestCase {
  	@Override
  	@Before
  	public void setUp() throws Exception {
  		WindowCacheConfig windowCacheConfig = new WindowCacheConfig();
  		windowCacheConfig.setPackedGitOpenFiles(1);
  		windowCacheConfig.install();
  		super.setUp();
  	}
  
  	@Override
  	@After
  	public void tearDown() throws Exception {
  		super.tearDown();
  		new WindowCacheConfig().install();
  	}
  
  	@Test
  	public void testObjectInNewPack() throws IncorrectObjectTypeException,
  			IOException {
  		// Create a new object in a new pack, and test that it is present.
  		//
  		final Repository eden = createBareRepository();
  		final RevObject o1 = writeBlob(eden, "o1");
  		pack(eden, o1);
  		assertEquals(o1.name(), parse(o1).name());
  	}
  
  	@Test
  	public void testObjectMovedToNewPack1()
  			throws IncorrectObjectTypeException, IOException {
  		// Create an object and pack it. Then remove that pack and put the
  		// object into a different pack file, with some other object. We
  		// still should be able to access the objects.
  		//
  		final Repository eden = createBareRepository();
  		final RevObject o1 = writeBlob(eden, "o1");
  		final File[] out1 = pack(eden, o1);
  		assertEquals(o1.name(), parse(o1).name());
  
  		final RevObject o2 = writeBlob(eden, "o2");
  		pack(eden, o2, o1);
  
  		// Force close, and then delete, the old pack.
  		//
  		whackCache();
  		delete(out1);
  
  		// Now here is the interesting thing. Will git figure the new
  		// object exists in the new pack, and not the old one.
  		//
  		assertEquals(o2.name(), parse(o2).name());
 		assertEquals(o1.name(), parse(o1).name());
 	}
 
 	@Test
 	public void testObjectMovedWithinPack()
 			throws IncorrectObjectTypeException, IOException {
 		// Create an object and pack it.
 		//
 		final Repository eden = createBareRepository();
 		final RevObject o1 = writeBlob(eden, "o1");
 		final File[] out1 = pack(eden, o1);
 		assertEquals(o1.name(), parse(o1).name());
 
 		// Force close the old pack.
 		//
 		whackCache();
 
 		// Now overwrite the old pack in place. This method of creating a
 		// different pack under the same file name is partially broken. We
 		// should also have a different file name because the list of objects
 		// within the pack has been modified.
 		//
 		final RevObject o2 = writeBlob(eden, "o2");
 		try (PackWriter pw = new PackWriter(eden)) {
 			pw.addObject(o2);
 			pw.addObject(o1);
 			write(out1, pw);
 		}
 
 		// Try the old name, then the new name. The old name should cause the
 		// pack to reload when it opens and the index and pack mismatch.
 		//
 		assertEquals(o1.name(), parse(o1).name());
 		assertEquals(o2.name(), parse(o2).name());
 	}
 
 	@Test
 	public void testObjectMovedToNewPack2()
 			throws IncorrectObjectTypeException, IOException {
 		// Create an object and pack it. Then remove that pack and put the
 		// object into a different pack file, with some other object. We
 		// still should be able to access the objects.
 		//
 		final Repository eden = createBareRepository();
 		final RevObject o1 = writeBlob(eden, "o1");
 		final File[] out1 = pack(eden, o1);
 		assertEquals(o1.name(), parse(o1).name());
 
 		final ObjectLoader load1 = db.open(o1, Constants.OBJ_BLOB);
 		assertNotNull(load1);
 
 		final RevObject o2 = writeBlob(eden, "o2");
 		pack(eden, o2, o1);
 
 		// Force close, and then delete, the old pack.
 		//
 		whackCache();
 		delete(out1);
 
 		// Now here is the interesting thing... can the loader we made
 		// earlier still resolve the object, even though its underlying
 		// pack is gone, but the object still exists.
 		//
 		final ObjectLoader load2 = db.open(o1, Constants.OBJ_BLOB);
 		assertNotNull(load2);
 		assertNotSame(load1, load2);
 
 		final byte[] data2 = load2.getCachedBytes();
 		final byte[] data1 = load1.getCachedBytes();
 		assertNotNull(data2);
 		assertNotNull(data1);
 		assertNotSame(data1, data2); // cache should be per-pack, not per object
 		assertArrayEquals(data1, data2);
 		assertEquals(load2.getType(), load1.getType());
 	}
 
 	private static void whackCache() {
 		final WindowCacheConfig config = new WindowCacheConfig();
 		config.setPackedGitOpenFiles(1);
 		config.install();
 	}
 
 	private RevObject parse(AnyObjectId id)
 			throws MissingObjectException, IOException {
 		try (RevWalk rw = new RevWalk(db)) {
 			return rw.parseAny(id);
 		}
 	}
 
 	private File[] pack(Repository src, RevObject... list)
 			throws IOException {
 		try (PackWriter pw = new PackWriter(src)) {
 			for (RevObject o : list) {
 				pw.addObject(o);
 			}
 
 			final ObjectId name = pw.computeName();
 			final File packFile = fullPackFileName(name, ".pack");
 			final File idxFile = fullPackFileName(name, ".idx");
 			final File[] files = new File[] { packFile, idxFile };
 			write(files, pw);
 			return files;
 		}
 	}
 
 	private static void write(File[] files, PackWriter pw)
 			throws IOException {
 		final Instant begin = FS.DETECTED
 				.lastModifiedInstant(files[0].getParentFile());
 		NullProgressMonitor m = NullProgressMonitor.INSTANCE;
 
 		try (OutputStream out = new BufferedOutputStream(
 				new FileOutputStream(files[0]))) {
 			pw.writePack(m, m, out);
 		}
 
 		try (OutputStream out = new BufferedOutputStream(
 				new FileOutputStream(files[1]))) {
 			pw.writeIndex(out);
 		}
 
 		touch(begin, files[0].getParentFile());
 	}
 
 	private static void delete(File[] list) throws IOException {
 		final Instant begin = FS.DETECTED
 				.lastModifiedInstant(list[0].getParentFile());
 		for (File f : list) {
 			FileUtils.delete(f);
 			assertFalse(f + " was removed", f.exists());
 		}
 		touch(begin, list[0].getParentFile());
 	}
 
 	private static void touch(Instant begin, File dir) throws IOException {
 		while (begin.compareTo(FS.DETECTED.lastModifiedInstant(dir)) >= 0) {
 			try {
 				Thread.sleep(25);
 			} catch (InterruptedException ie) {
 				//
 			}
 			FS.DETECTED.setLastModified(dir.toPath(), Instant.now());
 		}
 	}
 
 	private File fullPackFileName(ObjectId name, String suffix) {
 		final File packdir = db.getObjectDatabase().getPackDirectory();
 		return new File(packdir, "pack-" + name.name() + suffix);
 	}
 
 	private RevObject writeBlob(Repository repo, String data)
 			throws IOException {
 		final byte[] bytes = Constants.encode(data);
 		final ObjectId id;
 		try (ObjectInserter inserter = repo.newObjectInserter()) {
 			id = inserter.insert(Constants.OBJ_BLOB, bytes);
 			inserter.flush();
 		}
 		try {
 			parse(id);
 			fail("Object " + id.name() + " should not exist in test repository");
 		} catch (MissingObjectException e) {
 			// Ok
 		}
 		try (RevWalk revWalk = new RevWalk(repo)) {
 			return revWalk.lookupBlob(id);
 		}
 	}
 }