// 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.devtools.build.lib.analysis.BlazeDirectories;
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.analysis.config.InvalidConfigurationException;
import com.google.devtools.build.lib.analysis.config.PackageProviderForConfigurations;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
import com.google.devtools.build.lib.cmdline.PackageIdentifier;
import com.google.devtools.build.lib.events.EventHandler;
import com.google.devtools.build.lib.packages.NoSuchPackageException;
import com.google.devtools.build.lib.packages.NoSuchTargetException;
import com.google.devtools.build.lib.packages.Package;
import com.google.devtools.build.lib.packages.RuleClassProvider;
import com.google.devtools.build.lib.packages.Target;
import com.google.devtools.build.lib.skyframe.SkyframeExecutor.SkyframePackageLoader;
import com.google.devtools.build.lib.vfs.RootedPath;
import com.google.devtools.build.skyframe.MemoizingEvaluator;
import com.google.devtools.build.skyframe.SkyFunction;
import com.google.devtools.build.skyframe.SkyKey;

import java.io.IOException;

/**
 * Repeats functionality of {@link SkyframePackageLoader} but uses
 * {@link SkyFunction.Environment#getValue} instead of {@link MemoizingEvaluator#evaluate}
 * for node evaluation
 */
class SkyframePackageLoaderWithValueEnvironment implements PackageProviderForConfigurations {
  private final SkyFunction.Environment env;
  private final RuleClassProvider ruleClassProvider;

  public SkyframePackageLoaderWithValueEnvironment(SkyFunction.Environment env,
      RuleClassProvider ruleClassProvider) {
    this.env = env;
    this.ruleClassProvider = ruleClassProvider;
  }

  @Override
  public EventHandler getEventHandler() {
    return env.getListener();
  }

  private Package getPackage(final PackageIdentifier pkgIdentifier)
      throws NoSuchPackageException {
    SkyKey key = PackageValue.key(pkgIdentifier);
    PackageValue value = (PackageValue) env.getValueOrThrow(key, NoSuchPackageException.class);
    if (value != null) {
      return value.getPackage();
    }
    return null;
  }

  @Override
  public Target getTarget(Label label) throws NoSuchPackageException, NoSuchTargetException {
    Package pkg = getPackage(label.getPackageIdentifier());
    return pkg == null ? null : pkg.getTarget(label.getName());
  }

  @Override
  public void addDependency(Package pkg, String fileName) throws LabelSyntaxException, IOException {
    RootedPath fileRootedPath = RootedPath.toRootedPath(pkg.getSourceRoot(),
        pkg.getPackageIdentifier().getPathFragment().getRelative(fileName));
    FileValue result = (FileValue) env.getValue(FileValue.key(fileRootedPath));
    if (result != null && !result.exists()) {
      throw new IOException();
    }
  }

  @Override
  public <T extends Fragment> T getFragment(BuildOptions buildOptions, Class<T> fragmentType)
      throws InvalidConfigurationException {
    ConfigurationFragmentValue fragmentNode = (ConfigurationFragmentValue) env.getValueOrThrow(
        ConfigurationFragmentValue.key(buildOptions, fragmentType, ruleClassProvider),
        InvalidConfigurationException.class);
    if (fragmentNode == null) {
      return null;
    }
    return fragmentType.cast(fragmentNode.getFragment());
  }

  @Override
  public BlazeDirectories getDirectories() {
    return PrecomputedValue.BLAZE_DIRECTORIES.get(env);
  }

  @Override
  public boolean valuesMissing() {
    return env.valuesMissing();
  }
}