// Copyright 2014 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 com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Interner;
import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
import com.google.devtools.build.lib.analysis.config.BuildConfiguration.Fragment;
import com.google.devtools.build.lib.analysis.config.BuildOptions;
import com.google.devtools.build.lib.concurrent.BlazeInterners;
import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
import com.google.devtools.build.lib.packages.RuleClassProvider;
import com.google.devtools.build.lib.skyframe.serialization.DeserializationContext;
import com.google.devtools.build.lib.skyframe.serialization.InjectingObjectCodec;
import com.google.devtools.build.lib.skyframe.serialization.ObjectCodec;
import com.google.devtools.build.lib.skyframe.serialization.SerializationContext;
import com.google.devtools.build.lib.skyframe.serialization.SerializationException;
import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
import com.google.devtools.build.lib.skyframe.serialization.strings.StringCodecs;
import com.google.devtools.build.lib.util.Fingerprint;
import com.google.devtools.build.lib.vfs.FileSystemProvider;
import com.google.devtools.build.skyframe.SkyFunctionName;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;
import com.google.protobuf.CodedInputStream;
import com.google.protobuf.CodedOutputStream;
import java.io.IOException;
import java.util.Objects;
import javax.annotation.Nullable;

/** A Skyframe node representing a build configuration fragment. */
@Immutable
@ThreadSafe
@AutoCodec(dependency = FileSystemProvider.class)
public class ConfigurationFragmentValue implements SkyValue {
  public static final InjectingObjectCodec<ConfigurationFragmentValue, FileSystemProvider> CODEC =
      new ConfigurationFragmentValue_AutoCodec();

  @Nullable
  private final BuildConfiguration.Fragment fragment;

  ConfigurationFragmentValue(BuildConfiguration.Fragment fragment) {
    this.fragment = fragment;
  }

  public BuildConfiguration.Fragment getFragment() {
    return fragment;
  }

  @ThreadSafe
  public static ConfigurationFragmentKey key(
      BuildOptions buildOptions,
      Class<? extends Fragment> fragmentType,
      RuleClassProvider ruleClassProvider) {
    BuildOptions optionsKey =
        buildOptions.trim(
            BuildConfiguration.getOptionsClasses(
                ImmutableList.<Class<? extends BuildConfiguration.Fragment>>of(fragmentType),
                ruleClassProvider));
    return ConfigurationFragmentKey.of(optionsKey, fragmentType);
  }

  /** {@link SkyKey} for {@link ConfigurationFragmentValue}. */
  public static final class ConfigurationFragmentKey implements SkyKey {
    private static Interner<ConfigurationFragmentKey> interner = BlazeInterners.newWeakInterner();

    public static final ObjectCodec<ConfigurationFragmentKey> CODEC = new Codec();

    private final BuildOptions buildOptions;
    private final String checksum;
    private final Class<? extends Fragment> fragmentType;

    private ConfigurationFragmentKey(
        BuildOptions buildOptions, Class<? extends Fragment> fragmentType) {
      this.buildOptions = Preconditions.checkNotNull(buildOptions);
      this.checksum = Fingerprint.md5Digest(buildOptions.computeCacheKey());
      this.fragmentType = Preconditions.checkNotNull(fragmentType);
    }

    private static ConfigurationFragmentKey of(
        BuildOptions buildOptions, Class<? extends Fragment> fragmentType) {
      return interner.intern(new ConfigurationFragmentKey(buildOptions, fragmentType));
    }

    public BuildOptions getBuildOptions() {
      return buildOptions;
    }

    public Class<? extends Fragment> getFragmentType() {
      return fragmentType;
    }

    @Override
    public boolean equals(Object o) {
      if (this == o) {
        return true;
      }
      if (!(o instanceof ConfigurationFragmentKey)) {
        return false;
      }
      ConfigurationFragmentKey confObject = (ConfigurationFragmentKey) o;
      return Objects.equals(fragmentType, confObject.fragmentType)
          && Objects.equals(buildOptions, confObject.buildOptions);
    }

    @Override
    public int hashCode() {
      return Objects.hash(buildOptions, fragmentType);
    }

    @Override
    public String toString() {
      return String.format("ConfigurationFragmentKey(class=%s, checksum=%s)",
          fragmentType.getName(), checksum);
    }

    @Override
    public SkyFunctionName functionName() {
      return SkyFunctions.CONFIGURATION_FRAGMENT;
    }

    private static class Codec implements ObjectCodec<ConfigurationFragmentKey> {
      @Override
      public Class<ConfigurationFragmentKey> getEncodedClass() {
        return ConfigurationFragmentKey.class;
      }

      @Override
      public void serialize(
          SerializationContext context, ConfigurationFragmentKey obj, CodedOutputStream codedOut)
          throws SerializationException, IOException {
        BuildOptions.CODEC.serialize(context, obj.buildOptions, codedOut);
        StringCodecs.asciiOptimized().serialize(context, obj.fragmentType.getName(), codedOut);
      }

      @SuppressWarnings("unchecked") // Cast to Class<? extends Fragment>.
      @Override
      public ConfigurationFragmentKey deserialize(
          DeserializationContext context, CodedInputStream codedIn)
          throws SerializationException, IOException {

        try {
          return of(
              BuildOptions.CODEC.deserialize(context, codedIn),
              (Class<? extends Fragment>)
                  Class.forName(StringCodecs.asciiOptimized().deserialize(context, codedIn)));
        } catch (ClassNotFoundException e) {
          throw new SerializationException("Couldn't deserialize ConfigurationFragmentKey", e);
        }
      }
    }
  }
}