/*
    * Copyright (C) 2010, Christian Halstrick <christian.halstrick@sap.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.lib;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertFalse;
  import static org.junit.Assert.assertTrue;
  
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.time.Instant;
  
  import org.eclipse.jgit.api.Git;
  import org.eclipse.jgit.dircache.DirCache;
  import org.eclipse.jgit.junit.RepositoryTestCase;
  import org.eclipse.jgit.junit.time.TimeUtil;
  import org.eclipse.jgit.treewalk.FileTreeIterator;
  import org.eclipse.jgit.treewalk.WorkingTreeOptions;
  import org.eclipse.jgit.util.FS;
  import org.junit.Test;
  
  public class RacyGitTests extends RepositoryTestCase {
  
  	@Test
  	public void testRacyGitDetection() throws Exception {
  		// Reset to force creation of index file
  		try (Git git = new Git(db)) {
  			git.reset().call();
  		}
  
  		// wait to ensure that modtimes of the file doesn't match last index
  		// file modtime
  		fsTick(db.getIndexFile());
  
  		// create two files
  		File a = writeToWorkDir("a", "a");
  		File b = writeToWorkDir("b", "b");
  		TimeUtil.setLastModifiedOf(a.toPath(), b.toPath());
  		TimeUtil.setLastModifiedOf(b.toPath(), b.toPath());
  
  		// wait to ensure that file-modTimes and therefore index entry modTime
  		// doesn't match the modtime of index-file after next persistance
  		fsTick(b);
  
  		// now add both files to the index. No racy git expected
  		resetIndex(new FileTreeIterator(db));
  
  		assertEquals(
  				"[a, mode:100644, time:t0, length:1, content:a]"
  						+ "[b, mode:100644, time:t0, length:1, content:b]",
  				indexState(SMUDGE | MOD_TIME | LENGTH | CONTENT));
  
  		// wait to ensure the file 'a' is updated at t1.
  		fsTick(db.getIndexFile());
  
  		// Create a racy git situation. This is a situation that the index is
  		// updated and then a file is modified within the same tick of the
  		// filesystem timestamp resolution. By changing the index file
  		// artificially, we create a fake racy situation.
  		File updatedA = writeToWorkDir("a", "a2");
  		Instant newLastModified = TimeUtil
  				.setLastModifiedWithOffset(updatedA.toPath(), 100L);
  		resetIndex(new FileTreeIterator(db));
  		FS.DETECTED.setLastModified(db.getIndexFile().toPath(),
  				newLastModified);
  
  		DirCache dc = db.readDirCache();
  		// check index state: although racily clean a should not be reported as
  		// being dirty since we forcefully reset the index to match the working
  		// tree
  		assertEquals(
  				"[a, mode:100644, time:t1, smudged, length:0, content:a2]"
  						+ "[b, mode:100644, time:t0, length:1, content:b]",
  				indexState(SMUDGE | MOD_TIME | LENGTH | CONTENT));
  
  		// compare state of files in working tree with index to check that
  		// FileTreeIterator.isModified() works as expected
  		FileTreeIterator f = new FileTreeIterator(db.getWorkTree(), db.getFS(),
  				db.getConfig().get(WorkingTreeOptions.KEY));
  		assertTrue(f.findFile("a"));
  		try (ObjectReader reader = db.newObjectReader()) {
  			assertFalse(f.isModified(dc.getEntry("a"), false, reader));
  		}
  	}
  
  	private File writeToWorkDir(String path, String content) throws IOException {
  		File f = new File(db.getWorkTree(), path);
  		try (FileOutputStream fos = new FileOutputStream(f)) {
  			fos.write(content.getBytes(UTF_8));
  			return f;
 		}
 	}
 }