// 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.skyframe;

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

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.io.BaseEncoding;
import com.google.devtools.build.lib.analysis.util.BuildViewTestCase;
import com.google.devtools.build.lib.clock.BlazeClock;
import com.google.devtools.build.lib.cmdline.PackageIdentifier;
import com.google.devtools.build.lib.packages.Rule;
import com.google.devtools.build.lib.packages.RuleVisibility;
import com.google.devtools.build.lib.packages.Target;
import com.google.devtools.build.lib.packages.semantics.BuildLanguageOptions;
import com.google.devtools.build.lib.pkgcache.PackageOptions;
import com.google.devtools.build.lib.pkgcache.PathPackageLocator;
import com.google.devtools.build.lib.runtime.QuiescingExecutorsImpl;
import com.google.devtools.build.lib.skyframe.util.SkyframeExecutorTestUtils;
import com.google.devtools.build.lib.util.io.TimestampGranularityMonitor;
import com.google.devtools.build.lib.vfs.Root;
import com.google.devtools.build.skyframe.EvaluationResult;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.common.options.Options;
import java.util.Collection;
import java.util.UUID;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/**
 * Tests for the hash code calculated for Starlark RuleClasses based on the transitive closure of
 * the imports of their respective definition StarlarkEnvironments.
 */
@RunWith(JUnit4.class)
public class StarlarkFileContentHashTests extends BuildViewTestCase {

  @Before
  public final void createFiles() throws Exception  {
    scratch.file("foo/BUILD");
    scratch.file("bar/BUILD");
    scratch.file("helper/BUILD");

    scratch.file(
        "helper/ext.bzl",
        """
        def rule_impl(ctx):
            return None
        """);

    scratch.file(
        "foo/ext.bzl",
        """
        load("//helper:ext.bzl", "rule_impl")

        foo1 = rule(implementation = rule_impl)
        foo2 = rule(implementation = rule_impl)
        """);

    scratch.file(
        "bar/ext.bzl",
        """
        load("//helper:ext.bzl", "rule_impl")

        bar1 = rule(implementation = rule_impl)
        """);

    scratch.file(
        "pkg/BUILD",
        """
        load("//bar:ext.bzl", "bar1")
        load("//foo:ext.bzl", "foo1", "foo2")

        foo1(name = "foo1")

        foo2(name = "foo2")

        bar1(name = "bar1")
        """);
  }

  @Test
  public void testHashInvariance() throws Exception {
    assertThat(getHash("pkg", "foo1")).isEqualTo(getHash("pkg", "foo1"));
  }

  @Test
  public void testHashInvarianceAfterOverwritingFileWithSameContents() throws Exception {
    String bar1 = getHash("pkg", "bar1");
    scratch.overwriteFile(
        "bar/ext.bzl",
        """
        load("//helper:ext.bzl", "rule_impl")

        bar1 = rule(implementation = rule_impl)
        """);
    invalidatePackages();
    assertThat(getHash("pkg", "bar1")).isEqualTo(bar1);
  }

  @Test
  public void testHashSameForRulesDefinedInSameFile() throws Exception {
    assertThat(getHash("pkg", "foo2")).isEqualTo(getHash("pkg", "foo1"));
  }

  @Test
  public void testHashNotSameForRulesDefinedInDifferentFiles() throws Exception {
    assertNotEquals(getHash("pkg", "foo1"), getHash("pkg", "bar1"));
  }

  @Test
  public void testImmediateFileChangeChangesHash() throws Exception {
    String bar1 = getHash("pkg", "bar1");
    scratch.overwriteFile(
        "bar/ext.bzl",
        """
        load("//helper:ext.bzl", "rule_impl")
        # Some comments to change file hash

        bar1 = rule(implementation = rule_impl)
        """);
    invalidatePackages();
    assertNotEquals(bar1, getHash("pkg", "bar1"));
  }

  @Test
  public void testTransitiveFileChangeChangesHash() throws Exception {
    String bar1 = getHash("pkg", "bar1");
    String foo1 = getHash("pkg", "foo1");
    String foo2 = getHash("pkg", "foo2");
    scratch.overwriteFile(
        "helper/ext.bzl",
        """
        # Some comments to change file hash
        def rule_impl(ctx):
            return None
        """);
    invalidatePackages();
    assertNotEquals(bar1, getHash("pkg", "bar1"));
    assertNotEquals(foo1, getHash("pkg", "foo1"));
    assertNotEquals(foo2, getHash("pkg", "foo2"));
  }

  @Test
  public void testFileChangeDoesNotAffectRulesDefinedOutsideOfTransitiveClosure() throws Exception {
    String foo1 = getHash("pkg", "foo1");
    String foo2 = getHash("pkg", "foo2");
    scratch.overwriteFile(
        "bar/ext.bzl",
        """
        load("//helper:ext.bzl", "rule_impl")
        # Some comments to change file hash

        bar1 = rule(implementation = rule_impl)
        """);
    invalidatePackages();
    assertThat(getHash("pkg", "foo1")).isEqualTo(foo1);
    assertThat(getHash("pkg", "foo2")).isEqualTo(foo2);
  }

  private static void assertNotEquals(String hash, String hash2) {
    assertThat(hash.equals(hash2)).isFalse();
  }

  /**
   * Returns the hash code of the rule target defined by the pkg and the target name parameters.
   * Asserts that the targets and it's Starlark dependencies were loaded properly.
   */
  private String getHash(String pkg, String name) throws Exception {
    PackageOptions packageOptions = Options.getDefaults(PackageOptions.class);
    packageOptions.defaultVisibility = RuleVisibility.PUBLIC;
    packageOptions.showLoadingProgress = true;
    packageOptions.globbingThreads = 7;
    getSkyframeExecutor()
        .preparePackageLoading(
            new PathPackageLocator(
                outputBase,
                ImmutableList.of(Root.fromPath(rootDirectory)),
                BazelSkyframeExecutorConstants.BUILD_FILES_BY_PRIORITY),
            packageOptions,
            Options.getDefaults(BuildLanguageOptions.class),
            UUID.randomUUID(),
            ImmutableMap.<String, String>of(),
            QuiescingExecutorsImpl.forTesting(),
            new TimestampGranularityMonitor(BlazeClock.instance()));
    skyframeExecutor.setActionEnv(ImmutableMap.<String, String>of());
    SkyKey pkgLookupKey = PackageIdentifier.createInMainRepo(pkg);
    EvaluationResult<PackageValue> result =
        SkyframeExecutorTestUtils.evaluate(
            getSkyframeExecutor(), pkgLookupKey, /*keepGoing=*/ false, reporter);
    assertThat(result.hasError()).isFalse();
    Collection<Target> targets = result.get(pkgLookupKey).getPackage().getTargets().values();
    for (Target target : targets) {
      if (target.getName().equals(name)) {
        byte[] hash = ((Rule) target).getRuleClassObject().getRuleDefinitionEnvironmentDigest();
        return BaseEncoding.base16().lowerCase().encode(hash); // hexify
      }
    }
    throw new IllegalStateException("target not found: " + name);
  }
}