// 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 com.google.devtools.build.lib.analysis.BlazeDirectories;
import com.google.devtools.build.lib.analysis.ConfiguredRuleClassProvider;
import com.google.devtools.build.lib.analysis.config.BuildConfigurationValue;
import com.google.devtools.build.lib.analysis.config.FragmentFactory;
import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
import com.google.devtools.build.lib.cmdline.RepositoryName;
import com.google.devtools.build.lib.packages.RuleClassProvider;
import com.google.devtools.build.lib.packages.semantics.BuildLanguageOptions;
import com.google.devtools.build.skyframe.SkyFunction;
import com.google.devtools.build.skyframe.SkyFunctionException;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;
import net.starlark.java.eval.StarlarkSemantics;

/** A builder for {@link BuildConfigurationValue} instances. */
public final class BuildConfigurationFunction implements SkyFunction {

  private final BlazeDirectories directories;
  private final ConfiguredRuleClassProvider ruleClassProvider;
  private final FragmentFactory fragmentFactory = new FragmentFactory();

  public BuildConfigurationFunction(
      BlazeDirectories directories, RuleClassProvider ruleClassProvider) {
    this.directories = directories;
    this.ruleClassProvider = (ConfiguredRuleClassProvider) ruleClassProvider;
  }

  @Override
  public SkyValue compute(SkyKey skyKey, Environment env)
      throws InterruptedException, BuildConfigurationFunctionException {
    WorkspaceNameValue workspaceNameValue = (WorkspaceNameValue) env
        .getValue(WorkspaceNameValue.key());
    if (workspaceNameValue == null) {
      return null;
    }

    StarlarkSemantics starlarkSemantics = PrecomputedValue.STARLARK_SEMANTICS.get(env);
    if (starlarkSemantics == null) {
      return null;
    }

    BuildConfigurationKey key = (BuildConfigurationKey) skyKey.argument();
    try {
      return BuildConfigurationValue.create(
          key.getOptions(),
          RepositoryName.createFromValidStrippedName(workspaceNameValue.getName()),
          starlarkSemantics.getBool(BuildLanguageOptions.EXPERIMENTAL_SIBLING_REPOSITORY_LAYOUT),
          // Arguments below this are server-global.
          directories,
          ruleClassProvider,
          fragmentFactory);
    } catch (InvalidConfigurationException e) {
      throw new BuildConfigurationFunctionException(e);
    }
  }

  private static final class BuildConfigurationFunctionException extends SkyFunctionException {
    BuildConfigurationFunctionException(InvalidConfigurationException e) {
      super(e, Transience.PERSISTENT);
    }
  }
}