/*
    * Copyright (C) 2019 Google LLC 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.eclipse.jgit.lib.Ref.Storage.PACKED;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertThrows;
  import static org.junit.Assert.assertTrue;
  import static org.junit.Assume.assumeFalse;
  
  import java.io.File;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.util.Collections;
  import java.util.List;
  import java.util.stream.Collectors;
  
  import org.eclipse.jgit.internal.storage.file.FileReftableStack.Segment;
  import org.eclipse.jgit.internal.storage.reftable.MergedReftable;
  import org.eclipse.jgit.internal.storage.reftable.RefCursor;
  import org.eclipse.jgit.lib.Config;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.ObjectIdRef;
  import org.eclipse.jgit.lib.Ref;
  import org.eclipse.jgit.util.FileUtils;
  import org.eclipse.jgit.util.SystemReader;
  import org.junit.After;
  import org.junit.Before;
  import org.junit.Test;
  
  
  public class FileReftableStackTest {
  
  	private static Ref newRef(String name, ObjectId id) {
  		return new ObjectIdRef.PeeledNonTag(PACKED, name, id);
  	}
  
  	private File reftableDir;
  
  	@Before
  	public void setup() throws Exception {
  		reftableDir = FileUtils.createTempDir("rtstack", "", null);
  	}
  
  	@After
  	public void tearDown() throws Exception {
  		if (reftableDir != null) {
  			FileUtils.delete(reftableDir, FileUtils.RECURSIVE);
  		}
  	}
  
  	void writeBranches(FileReftableStack stack, String template, int start,
  			int N) throws IOException {
  		for (int i = 0; i < N; i++) {
  			while (true) {
  				final long next = stack.getMergedReftable().maxUpdateIndex()
  						+ 1;
  
  				String name = String.format(template,
  						Integer.valueOf(start + i));
  				Ref r = newRef(name, ObjectId.zeroId());
  				boolean ok = stack.addReftable(rw -> {
  					rw.setMinUpdateIndex(next).setMaxUpdateIndex(next).begin()
  							.writeRef(r);
  				});
  				if (ok) {
  					break;
  				}
  			}
  		}
  	}
  
  	public void testCompaction(int N) throws Exception {
  		try (FileReftableStack stack = new FileReftableStack(
  				new File(reftableDir, "refs"), reftableDir, null,
  				() -> new Config())) {
  			writeBranches(stack, "refs/heads/branch%d", 0, N);
  			MergedReftable table = stack.getMergedReftable();
  			for (int i = 1; i < N; i++) {
  				String name = String.format("refs/heads/branch%d",
  						Integer.valueOf(i));
  				RefCursor c = table.seekRef(name);
  				assertTrue(c.next());
  				assertEquals(ObjectId.zeroId(), c.getRef().getObjectId());
  			}
  
  			List<String> files = Files.list(reftableDir.toPath())
  					.map(Path::getFileName).map(Path::toString)
  					.collect(Collectors.toList());
 			Collections.sort(files);
 
 			assertTrue(files.size() < 20);
 
 			FileReftableStack.CompactionStats stats = stack.getStats();
 			assertEquals(0, stats.failed);
 			assertTrue(stats.attempted < N);
 			assertTrue(stats.refCount < FileReftableStack.log(N) * N);
 		}
 	}
 
 	@Test
 	public void testCompaction9() throws Exception {
 		testCompaction(9);
 	}
 
 	@Test
 	public void testCompaction1024() throws Exception {
 		testCompaction(1024);
 	}
 
 	@SuppressWarnings("resource")
 	@Test
 	public void missingReftable() throws Exception {
 		// Can't delete in-use files on Windows.
 		assumeFalse(SystemReader.getInstance().isWindows());
 
 		try (FileReftableStack stack = new FileReftableStack(
 				new File(reftableDir, "refs"), reftableDir, null,
 				() -> new Config())) {
 			outer: for (int i = 0; i < 10; i++) {
 				final long next = stack.getMergedReftable().maxUpdateIndex()
 						+ 1;
 				String name = String.format("branch%d", Integer.valueOf(i));
 				Ref r = newRef(name, ObjectId.zeroId());
 				boolean ok = stack.addReftable(rw -> {
 					rw.setMinUpdateIndex(next).setMaxUpdateIndex(next).begin()
 							.writeRef(r);
 				});
 				assertTrue(ok);
 
 				List<Path> files = Files.list(reftableDir.toPath())
 						.collect(Collectors.toList());
 				for (int j = 0; j < files.size(); j++) {
 					Path f = files.get(j);
 					Path fileName = f.getFileName();
 					if (fileName != null
 							&& fileName.toString().endsWith(".ref")) {
 						Files.delete(f);
 						break outer;
 					}
 				}
 			}
 		}
 		assertThrows(FileNotFoundException.class,
 				() -> new FileReftableStack(new File(reftableDir, "refs"),
 						reftableDir, null, () -> new Config()));
 	}
 
 	@Test
 	public void testSegments() {
 		long in[] = { 1024, 1024, 1536, 100, 64, 50, 25, 24 };
 		List<Segment> got = FileReftableStack.segmentSizes(in);
 		Segment want[] = { new Segment(0, 3, 10, 3584),
 				new Segment(3, 5, 6, 164), new Segment(5, 6, 5, 50),
 				new Segment(6, 8, 4, 49), };
 		assertEquals(got.size(), want.length);
 		for (int i = 0; i < want.length; i++) {
 			assertTrue(want[i].equals(got.get(i)));
 		}
 	}
 
 	@Test
 	public void testLog2() throws Exception {
 		assertEquals(10, FileReftableStack.log(1024));
 		assertEquals(10, FileReftableStack.log(1025));
 		assertEquals(10, FileReftableStack.log(2047));
 	}
 }