// 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.bazel.rules;

import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.analysis.actions.FileWriteActionContext;
import com.google.devtools.build.lib.analysis.actions.TemplateExpansionContext;
import com.google.devtools.build.lib.buildtool.BuildRequest;
import com.google.devtools.build.lib.exec.ExecutionOptions;
import com.google.devtools.build.lib.exec.ExecutorBuilder;
import com.google.devtools.build.lib.exec.SpawnCache;
import com.google.devtools.build.lib.remote.RemoteModule;
import com.google.devtools.build.lib.remote.options.RemoteOptions;
import com.google.devtools.build.lib.rules.android.WriteAdbArgsActionContext;
import com.google.devtools.build.lib.rules.cpp.CppIncludeExtractionContext;
import com.google.devtools.build.lib.rules.cpp.CppIncludeScanningContext;
import com.google.devtools.build.lib.runtime.BlazeModule;
import com.google.devtools.build.lib.runtime.Command;
import com.google.devtools.build.lib.runtime.CommandEnvironment;
import com.google.devtools.build.lib.util.OS;
import com.google.devtools.build.lib.util.RegexFilter;
import com.google.devtools.common.options.OptionsBase;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/** Module which registers the strategy options for Bazel. */
public class BazelStrategyModule extends BlazeModule {
  @Override
  public Iterable<Class<? extends OptionsBase>> getCommandOptions(Command command) {
    return "build".equals(command.name())
        ? ImmutableList.of(ExecutionOptions.class, RemoteOptions.class)
        : ImmutableList.of();
  }

  @Override
  public void executorInit(CommandEnvironment env, BuildRequest request, ExecutorBuilder builder) {
    builder.addActionContext(new WriteAdbArgsActionContext(env.getClientEnv().get("HOME")));
    ExecutionOptions options = env.getOptions().getOptions(ExecutionOptions.class);
    RemoteOptions remoteOptions = env.getOptions().getOptions(RemoteOptions.class);

    List<String> spawnStrategies = new ArrayList<>(options.spawnStrategy);

    if (options.incompatibleListBasedExecutionStrategySelection) {
      if (spawnStrategies.isEmpty()) {
        if (RemoteModule.shouldEnableRemoteExecution(remoteOptions)) {
          spawnStrategies.add("remote");
        }
        spawnStrategies.add("worker");
        // Sandboxing is not yet available on Windows.
        if (OS.getCurrent() != OS.WINDOWS) {
          spawnStrategies.add("sandboxed");
        }
        spawnStrategies.add("local");
      }
    } else {
      // Default strategies for certain mnemonics - they can be overridden by --strategy= flags.
      builder.addStrategyByMnemonic("Javac", ImmutableList.of("worker"));
      builder.addStrategyByMnemonic("Closure", ImmutableList.of("worker"));
      builder.addStrategyByMnemonic("DexBuilder", ImmutableList.of("worker"));
      builder.addStrategyByMnemonic("Desugar", ImmutableList.of("worker"));

      // The --spawn_strategy= flag is a bit special: If it's set to the empty string, we actually
      // have to pass a literal empty string to the builder to trigger the "use the strategy that
      // was registered last" behavior. Otherwise we would have no default strategy at all and Bazel
      // would crash.
      if (spawnStrategies.isEmpty()) {
        spawnStrategies = ImmutableList.of("");
      }
    }

    // Allow genrule_strategy to also be overridden by --strategy= flags.
    builder.addStrategyByMnemonic("Genrule", options.genruleStrategy);

    for (Map.Entry<String, List<String>> strategy : options.strategy) {
      builder.addStrategyByMnemonic(strategy.getKey(), strategy.getValue());
    }

    builder.addStrategyByMnemonic("", spawnStrategies);

    for (Map.Entry<RegexFilter, List<String>> entry : options.strategyByRegexp) {
      builder.addStrategyByRegexp(entry.getKey(), entry.getValue());
    }

    builder
        .addStrategyByContext(CppIncludeExtractionContext.class, "")
        .addStrategyByContext(CppIncludeScanningContext.class, "")
        .addStrategyByContext(FileWriteActionContext.class, "")
        .addStrategyByContext(TemplateExpansionContext.class, "")
        .addStrategyByContext(WriteAdbArgsActionContext.class, "")
        .addStrategyByContext(SpawnCache.class, "");
  }
}