// Copyright (C) 2022 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.googlesource.gerrit.modules.cache.chroniclemap;

import static com.google.common.truth.Truth.assertThat;
import static com.googlesource.gerrit.modules.cache.chroniclemap.CacheKeysIndex.tempIndexFile;
import static java.util.stream.Collectors.toList;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.verifyNoInteractions;

import com.google.gerrit.metrics.DisabledMetricMaker;
import com.google.gerrit.server.cache.serialize.StringCacheSerializer;
import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.function.Consumer;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;

public class CacheKeysIndexTest {
  private static final String CACHE_NAME = "test-cache";
  @Rule public TemporaryFolder temporaryFolder = new TemporaryFolder();

  private CacheKeysIndex<String> index;
  private File indexFile;

  @Before
  public void setup() throws IOException {
    CacheSerializers.registerCacheKeySerializer(CACHE_NAME, StringCacheSerializer.INSTANCE);
    indexFile = temporaryFolder.newFolder().toPath().resolve("cache.index").toFile();
    index = new CacheKeysIndex<>(new DisabledMetricMaker(), CACHE_NAME, indexFile, false);
  }

  @Test
  public void add_shouldUpdateElementPositionWhenAlreadyInSet() {
    index.add("foo", 2L);
    index.add("bar", 1L);
    assertThat(keys(index)).containsExactly("foo", "bar");

    index.add("foo", 1L);
    assertThat(keys(index)).containsExactly("bar", "foo");
  }

  @Test
  public void add_shouldUpdateElementInsertionTimeWhenNewerGetsAdded() {
    index.add("foo", 1L);
    index.add("foo", 2L);

    CacheKeysIndex<String>.TimedKey key = index.keys().iterator().next();
    assertThat(key.getKey()).isEqualTo("foo");
    assertThat(key.getCreated()).isEqualTo(2L);
  }

  @Test
  public void refresh_shouldRefreshInsertionTimeOnRefresh() {
    index.add("foo", 1L);
    index.refresh("foo");

    CacheKeysIndex<String>.TimedKey key = index.keys().iterator().next();
    assertThat(key.getKey()).isEqualTo("foo");
    assertThat(key.getCreated()).isGreaterThan(1L);
  }

  @Test
  @SuppressWarnings("unchecked")
  public void remove_shouldRemoveAndConsumeKeysOlderThan() {
    long than = 5l;
    index.add("newerThan", 10L);
    index.add("olderThan", 2L);
    Consumer<String> consumer = mock(Consumer.class);

    index.removeAndConsumeKeysOlderThan(than, consumer);

    verify(consumer).accept("olderThan");
    assertThat(keys(index)).containsExactly("newerThan");
  }

  @Test
  @SuppressWarnings("unchecked")
  public void remove_shouldReturnFalseIfThereIsNoLruToRemove() {
    Consumer<String> consumer = mock(Consumer.class);

    boolean actual = index.removeAndConsumeLruKey(consumer);

    assertThat(actual).isEqualTo(false);
    verifyNoInteractions(consumer);
  }

  @Test
  @SuppressWarnings("unchecked")
  public void remove_shouldRemoveAndConsumeLruKey() {
    index.add("older", 1L);
    index.add("newer", 1L);
    Consumer<String> consumer = mock(Consumer.class);

    boolean actual = index.removeAndConsumeLruKey(consumer);

    assertThat(actual).isEqualTo(true);
    verify(consumer).accept("older");
    assertThat(keys(index)).containsExactly("newer");
  }

  @Test
  public void persist_shouldPersistAndRestoreKeys() {
    index.add("older", 1L);
    index.add("newer", 1L);
    assertThat(indexFile.exists()).isFalse();

    index.persist();
    assertThat(indexFile.isFile()).isTrue();
    assertThat(indexFile.canRead()).isTrue();

    index.clear();
    assertThat(keys(index)).isEmpty();

    index.restore(true);
    assertThat(keys(index)).containsExactly("newer", "older");
  }

  @Test
  public void restore_shouldDeleteExistingTemporaryIndexStorageFileDuringRestore()
      throws IOException {
    File indexTempFile = tempIndexFile(indexFile);
    indexTempFile.createNewFile();
    assertThat(indexTempFile.isFile()).isTrue();

    index.restore(true);

    assertThat(indexTempFile.exists()).isFalse();
  }

  private static List<String> keys(CacheKeysIndex<String> index) {
    return index.keys().stream().map(CacheKeysIndex.TimedKey::getKey).collect(toList());
  }
}