// Copyright 2017 The Bazel Authors. All rights reserved.
//
// 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.google.devtools.build.lib.actions;

import static com.google.common.truth.Truth.assertThat;

import com.google.common.base.Predicates;
import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.actions.ActionCacheChecker.Token;
import com.google.devtools.build.lib.actions.cache.ActionCache;
import com.google.devtools.build.lib.actions.cache.CompactPersistentActionCache;
import com.google.devtools.build.lib.actions.cache.Md5Digest;
import com.google.devtools.build.lib.actions.cache.Metadata;
import com.google.devtools.build.lib.actions.cache.MetadataHandler;
import com.google.devtools.build.lib.actions.cache.Protos.ActionCacheStatistics;
import com.google.devtools.build.lib.actions.cache.Protos.ActionCacheStatistics.MissDetail;
import com.google.devtools.build.lib.actions.cache.Protos.ActionCacheStatistics.MissReason;
import com.google.devtools.build.lib.actions.util.ActionsTestUtil.FakeArtifactResolverBase;
import com.google.devtools.build.lib.actions.util.ActionsTestUtil.FakeMetadataHandlerBase;
import com.google.devtools.build.lib.actions.util.ActionsTestUtil.MissDetailsBuilder;
import com.google.devtools.build.lib.actions.util.ActionsTestUtil.NullAction;
import com.google.devtools.build.lib.clock.Clock;
import com.google.devtools.build.lib.skyframe.FileArtifactValue;
import com.google.devtools.build.lib.testutil.ManualClock;
import com.google.devtools.build.lib.testutil.Scratch;
import com.google.devtools.build.lib.vfs.FileSystem;
import com.google.devtools.build.lib.vfs.FileSystemUtils;
import com.google.devtools.build.lib.vfs.Path;
import java.io.IOException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

@RunWith(JUnit4.class)
public class ActionCacheCheckerTest {
  private CorruptibleCompactPersistentActionCache cache;
  private ActionCacheChecker cacheChecker;
  private Set<Path> filesToDelete;

  @Before
  public void setupCache() throws Exception {
    Scratch scratch = new Scratch();
    Clock clock = new ManualClock();
    ArtifactResolver artifactResolver = new FakeArtifactResolverBase();

    cache = new CorruptibleCompactPersistentActionCache(scratch.resolve("/cache/test.dat"), clock);
    cacheChecker = new ActionCacheChecker(cache, artifactResolver, Predicates.alwaysTrue(), null);
  }

  @Before
  public void clearFilesToDeleteAfterTest() throws Exception {
    filesToDelete = new HashSet<>();
  }

  @After
  public void deleteFilesCreatedDuringTest() throws Exception {
    for (Path path : filesToDelete) {
      path.delete();
    }
  }

  /** "Executes" the given action from the point of view of the cache's lifecycle. */
  private void runAction(Action action) throws Exception {
    runAction(action, new HashMap<>());
  }

  /**
   * "Executes" the given action from the point of view of the cache's lifecycle with a custom
   * client environment.
   */
  private void runAction(Action action, Map<String, String> clientEnv) throws Exception {
    MetadataHandler metadataHandler = new FakeMetadataHandler();

    for (Artifact artifact : action.getOutputs()) {
      Path path = artifact.getPath();

      // Record all action outputs as files to be deleted across tests to prevent cross-test
      // pollution.  We need to do this on a path basis because we don't know upfront which file
      // system they live in so we cannot just recreate the file system.  (E.g. all NullActions
      // share an in-memory file system to hold dummy outputs.)
      filesToDelete.add(path);

      if (!path.exists()) {
        FileSystemUtils.writeContentAsLatin1(path, "");
      }
    }

    Token token = cacheChecker.getTokenIfNeedToExecute(
        action, null, clientEnv, null, metadataHandler);
    if (token != null) {
      // Real action execution would happen here.
      cacheChecker.afterExecution(action, token, metadataHandler, clientEnv);
    }
  }

  /** Ensures that the cache statistics match exactly the given values. */
  private void assertStatistics(int hits, Iterable<MissDetail> misses) {
    ActionCacheStatistics.Builder builder = ActionCacheStatistics.newBuilder();
    cache.mergeIntoActionCacheStatistics(builder);
    ActionCacheStatistics stats = builder.build();

    assertThat(stats.getHits()).isEqualTo(hits);
    assertThat(stats.getMissDetailsList()).containsExactlyElementsIn(misses);
  }

  private void doTestNotCached(Action action, MissReason missReason) throws Exception {
    runAction(action);

    assertStatistics(0, new MissDetailsBuilder().set(missReason, 1).build());
  }

  private void doTestCached(Action action, MissReason missReason) throws Exception {
    int runs = 5;
    for (int i = 0; i < runs; i++) {
      runAction(action);
    }

    assertStatistics(runs - 1, new MissDetailsBuilder().set(missReason, 1).build());
  }

  private void doTestCorruptedCacheEntry(Action action) throws Exception {
    cache.corruptAllEntries();
    runAction(action);

    assertStatistics(
        0,
        new MissDetailsBuilder().set(MissReason.CORRUPTED_CACHE_ENTRY, 1).build());
  }

  @Test
  public void testNoActivity() throws Exception {
    assertStatistics(0, new MissDetailsBuilder().build());
  }

  @Test
  public void testNotCached() throws Exception {
    doTestNotCached(new NullAction(), MissReason.NOT_CACHED);
  }

  @Test
  public void testCached() throws Exception {
    doTestCached(new NullAction(), MissReason.NOT_CACHED);
  }

  @Test
  public void testCorruptedCacheEntry() throws Exception {
    doTestCorruptedCacheEntry(new NullAction());
  }

  @Test
  public void testDifferentActionKey() throws Exception {
    Action action = new NullAction() {
      @Override
      protected String computeKey() {
        return "key1";
      }
    };
    runAction(action);
    action = new NullAction() {
      @Override
      protected String computeKey() {
        return "key2";
      }
    };
    runAction(action);

    assertStatistics(
        0,
        new MissDetailsBuilder()
            .set(MissReason.DIFFERENT_ACTION_KEY, 1)
            .set(MissReason.NOT_CACHED, 1)
            .build());
  }

  @Test
  public void testDifferentEnvironment() throws Exception {
    Action action = new NullAction() {
      @Override
      public Iterable<String> getClientEnvironmentVariables() {
        return ImmutableList.of("used-var");
      }
    };
    Map<String, String> clientEnv = new HashMap<>();
    clientEnv.put("unused-var", "1");
    runAction(action, clientEnv);  // Not cached.
    clientEnv.remove("unused-var");
    runAction(action, clientEnv);  // Cache hit because we only modified uninteresting variables.
    clientEnv.put("used-var", "2");
    runAction(action, clientEnv);  // Cache miss because of different environment.
    runAction(action, clientEnv);  // Cache hit because we did not change anything.

    assertStatistics(
        2,
        new MissDetailsBuilder()
            .set(MissReason.DIFFERENT_ENVIRONMENT, 1)
            .set(MissReason.NOT_CACHED, 1)
            .build());
  }

  @Test
  public void testDifferentFiles() throws Exception {
    Action action = new NullAction();
    runAction(action);  // Not cached.
    FileSystemUtils.writeContentAsLatin1(action.getPrimaryOutput().getPath(), "modified");
    runAction(action);  // Cache miss because output files were modified.

    assertStatistics(
        0,
        new MissDetailsBuilder()
            .set(MissReason.DIFFERENT_FILES, 1)
            .set(MissReason.NOT_CACHED, 1)
            .build());
  }

  @Test
  public void testUnconditionalExecution() throws Exception {
    Action action = new NullAction() {
      @Override
      public boolean executeUnconditionally() {
        return true;
      }

      @Override
      public boolean isVolatile() {
        return true;
      }
    };

    int runs = 5;
    for (int i = 0; i < runs; i++) {
      runAction(action);
    }

    assertStatistics(
        0, new MissDetailsBuilder().set(MissReason.UNCONDITIONAL_EXECUTION, runs).build());
  }

  @Test
  public void testMiddleman_NotCached() throws Exception {
    doTestNotCached(new NullMiddlemanAction(), MissReason.DIFFERENT_DEPS);
  }

  @Test
  public void testMiddleman_Cached() throws Exception {
    doTestCached(new NullMiddlemanAction(), MissReason.DIFFERENT_DEPS);
  }

  @Test
  public void testMiddleman_CorruptedCacheEntry() throws Exception {
    doTestCorruptedCacheEntry(new NullMiddlemanAction());
  }

  @Test
  public void testMiddleman_DifferentFiles() throws Exception {
    Action action = new NullMiddlemanAction() {
      @Override
      public synchronized Iterable<Artifact> getInputs() {
        FileSystem fileSystem = getPrimaryOutput().getPath().getFileSystem();
        Path path = fileSystem.getPath("/input");
        Root root = Root.asSourceRoot(fileSystem.getPath("/"));
        return ImmutableList.of(new Artifact(path, root));
      }
    };
    runAction(action);  // Not cached so recorded as different deps.
    FileSystemUtils.writeContentAsLatin1(action.getPrimaryInput().getPath(), "modified");
    runAction(action);  // Cache miss because input files were modified.
    FileSystemUtils.writeContentAsLatin1(action.getPrimaryOutput().getPath(), "modified");
    runAction(action);  // Outputs are not considered for middleman actions, so this is a cache hit.
    runAction(action);  // Outputs are not considered for middleman actions, so this is a cache hit.

    assertStatistics(
        2,
        new MissDetailsBuilder()
            .set(MissReason.DIFFERENT_DEPS, 1)
            .set(MissReason.DIFFERENT_FILES, 1)
            .build());
  }

  /** A {@link CompactPersistentActionCache} that allows injecting corruption for testing. */
  private static class CorruptibleCompactPersistentActionCache
      extends CompactPersistentActionCache {
    private boolean corrupted = false;

    CorruptibleCompactPersistentActionCache(Path cacheRoot, Clock clock) throws IOException {
      super(cacheRoot, clock);
    }

    void corruptAllEntries() {
      corrupted = true;
    }

    @Override
    public Entry get(String key) {
      if (corrupted) {
        return ActionCache.Entry.CORRUPTED;
      } else {
        return super.get(key);
      }
    }
  }

  /** A null middleman action. */
  private static class NullMiddlemanAction extends NullAction {
    @Override
    public MiddlemanType getActionType() {
      return MiddlemanType.RUNFILES_MIDDLEMAN;
    }
  }

  /** A fake metadata handler that is able to obtain metadata from the file system. */
  private static class FakeMetadataHandler extends FakeMetadataHandlerBase {
    @Override
    public Metadata getMetadata(Artifact artifact) throws IOException {
      return FileArtifactValue.create(artifact);
    }

    @Override
    public void setDigestForVirtualArtifact(Artifact artifact, Md5Digest md5Digest) {

    }
  }
}