// Copyright 2015 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.pkgcache;

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

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.packages.ConstantRuleVisibility;
import com.google.devtools.build.lib.packages.util.PackageLoadingTestCase;
import com.google.devtools.build.lib.skyframe.TransitiveTargetKey;
import com.google.devtools.build.lib.skyframe.TransitiveTargetValue;
import com.google.devtools.build.lib.vfs.DigestHashFunction;
import com.google.devtools.build.lib.vfs.FileStatus;
import com.google.devtools.build.lib.vfs.FileSystem;
import com.google.devtools.build.lib.vfs.ModifiedFileSet;
import com.google.devtools.build.lib.vfs.Path;
import com.google.devtools.build.lib.vfs.PathFragment;
import com.google.devtools.build.lib.vfs.Root;
import com.google.devtools.build.lib.vfs.inmemoryfs.InMemoryFileSystem;
import com.google.devtools.build.skyframe.EvaluationContext;
import com.google.devtools.build.skyframe.EvaluationResult;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;
import java.io.IOException;
import java.util.function.Function;
import javax.annotation.Nullable;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/**
 * Tests for recovering from IOExceptions thrown by the filesystem when reading BUILD files. Needs
 * its own test class because it uses a custom filesystem.
 */
@RunWith(JUnit4.class)
public class IOExceptionsTest extends PackageLoadingTestCase {
  private static String nullFunction(PathFragment p) {
    return null;
  }

  private Function<PathFragment, String> crashMessage = IOExceptionsTest::nullFunction;

  @Before
  public final void initializeVisitor() {
    setUpSkyframe(ConstantRuleVisibility.PRIVATE);
  }

  private boolean visitTransitively(Label label) throws InterruptedException {
    SkyKey key = TransitiveTargetKey.of(label);
    EvaluationContext evaluationContext =
        EvaluationContext.newBuilder().setNumThreads(5).setEventHandler(reporter).build();
    EvaluationResult<SkyValue> result =
        skyframeExecutor.prepareAndGet(ImmutableSet.of(key), evaluationContext);
    TransitiveTargetValue value = (TransitiveTargetValue) result.get(key);
    boolean hasTransitiveError = (value == null) || value.encounteredLoadingError();
    return !result.hasError() && !hasTransitiveError;
  }

  protected void syncPackages() throws Exception {
    skyframeExecutor.invalidateFilesUnderPathForTesting(
        reporter, ModifiedFileSet.EVERYTHING_MODIFIED, Root.fromPath(rootDirectory));
  }

  @Override
  protected FileSystem createFileSystem() {
    return new InMemoryFileSystem(DigestHashFunction.SHA256) {
      @Nullable
      @Override
      public FileStatus statIfFound(PathFragment path, boolean followSymlinks) throws IOException {
        String crash = crashMessage.apply(path);
        if (crash != null) {
          throw new IOException(crash);
        }
        return super.statIfFound(path, followSymlinks);
      }
    };
  }

  @Test
  public void testBasicFailure() throws Exception {
    reporter.removeHandler(failFastHandler); // expect errors
    final Path buildPath = scratch.file("pkg/BUILD",
        "sh_library(name = 'x')");
    crashMessage =
        path -> buildPath.asFragment().equals(path) ? "custom crash: " + buildPath : null;
    assertThat(visitTransitively(Label.parseAbsolute("//pkg:x", ImmutableMap.of()))).isFalse();
    scratch.overwriteFile("pkg/BUILD",
        "# another comment to force reload",
        "sh_library(name = 'x')");
    crashMessage = IOExceptionsTest::nullFunction;
    syncPackages();
    eventCollector.clear();
    reporter.addHandler(failFastHandler);
    assertThat(visitTransitively(Label.parseAbsolute("//pkg:x", ImmutableMap.of()))).isTrue();
    assertNoEvents();
  }


  @Test
  public void testNestedFailure() throws Exception {
    reporter.removeHandler(failFastHandler); // expect errors
    scratch.file("top/BUILD",
        "sh_library(name = 'top', deps = ['//pkg:x'])");
    final Path buildPath = scratch.file("pkg/BUILD",
        "sh_library(name = 'x')");
    crashMessage =
        path -> buildPath.asFragment().equals(path) ? "custom crash: " + buildPath : null;
    assertThat(visitTransitively(Label.parseAbsolute("//top:top", ImmutableMap.of()))).isFalse();
    assertContainsEvent("no such package 'pkg'");
    assertContainsEvent("custom crash");
    assertThat(eventCollector).hasSize(1);
    scratch.overwriteFile(
        "pkg/BUILD", "# another comment to force reload", "sh_library(name = 'x')");
    crashMessage = IOExceptionsTest::nullFunction;
    syncPackages();
    eventCollector.clear();
    reporter.addHandler(failFastHandler);
    assertThat(visitTransitively(Label.parseAbsolute("//top:top", ImmutableMap.of()))).isTrue();
    assertNoEvents();
  }

  @Test
  public void testOneLevelUpFailure() throws Exception {
    reporter.removeHandler(failFastHandler); // expect errors
    final Path buildPath = scratch.file("top/BUILD",
        "sh_library(name = 'x')");
    buildPath.getParentDirectory().getRelative("pkg").createDirectory();
    crashMessage =
        path -> buildPath.asFragment().equals(path) ? "custom crash: " + buildPath : null;
    assertThat(visitTransitively(Label.parseAbsolute("//top/pkg:x", ImmutableMap.of()))).isFalse();
  }
}