// Copyright 2017 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.rules.cpp;

import static com.google.devtools.build.lib.packages.Attribute.attr;
import static com.google.devtools.build.lib.packages.BuildType.LABEL;
import static com.google.devtools.build.lib.packages.BuildType.NODEP_LABEL;

import com.google.common.collect.ImmutableMap;
import com.google.devtools.build.lib.actions.MutableActionGraph.ActionConflictException;
import com.google.devtools.build.lib.analysis.BaseRuleClasses;
import com.google.devtools.build.lib.analysis.ConfiguredTarget;
import com.google.devtools.build.lib.analysis.PlatformConfiguration;
import com.google.devtools.build.lib.analysis.RuleConfiguredTargetBuilder;
import com.google.devtools.build.lib.analysis.RuleConfiguredTargetFactory;
import com.google.devtools.build.lib.analysis.RuleContext;
import com.google.devtools.build.lib.analysis.RuleDefinition;
import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
import com.google.devtools.build.lib.analysis.Runfiles;
import com.google.devtools.build.lib.analysis.RunfilesProvider;
import com.google.devtools.build.lib.analysis.TemplateVariableInfo;
import com.google.devtools.build.lib.analysis.platform.ToolchainInfo;
import com.google.devtools.build.lib.packages.RuleClass;
import com.google.devtools.build.lib.packages.RuleClass.ToolchainTransitionMode;

/** Implementation of the {@code cc_toolchain_alias} rule. */
public class CcToolchainAliasRule implements RuleDefinition {
  @Override
  public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env) {
    return builder
        .requiresConfigurationFragments(CppConfiguration.class)
        .removeAttribute("licenses")
        .removeAttribute("distribs")
        .add(
            attr(CcToolchain.CC_TOOLCHAIN_DEFAULT_ATTRIBUTE_NAME, LABEL)
                .mandatoryProviders(CcToolchainProvider.PROVIDER.id())
                .value(CppRuleClasses.ccToolchainAttribute(env)))
        .add(
            attr(CcToolchain.CC_TOOLCHAIN_TYPE_ATTRIBUTE_NAME, NODEP_LABEL)
                .value(CppRuleClasses.ccToolchainTypeAttribute(env)))
        .requiresConfigurationFragments(PlatformConfiguration.class)
        .addRequiredToolchains(CppRuleClasses.ccToolchainTypeAttribute(env))
        .useToolchainTransition(ToolchainTransitionMode.ENABLED)
        .build();
  }

  @Override
  public Metadata getMetadata() {
    return Metadata.builder()
        .name("cc_toolchain_alias")
        .ancestors(BaseRuleClasses.NativeBuildRule.class)
        .factoryClass(CcToolchainAlias.class)
        .build();
  }

  /** Implementation of cc_toolchain_alias. */
  public static class CcToolchainAlias implements RuleConfiguredTargetFactory {
    @Override
    public ConfiguredTarget create(RuleContext ruleContext)
        throws InterruptedException, RuleErrorException, ActionConflictException {

      CcToolchainProvider ccToolchainProvider =
          CppHelper.getToolchainUsingDefaultCcToolchainAttribute(ruleContext);

      TemplateVariableInfo templateVariableInfo =
          CcToolchain.createMakeVariableProvider(
              ccToolchainProvider, ruleContext.getRule().getLocation());

      ToolchainInfo toolchain =
          new ToolchainInfo(
              ImmutableMap.<String, Object>builder()
                  .put("cc", ccToolchainProvider)
                  // Add a clear signal that this is a CcToolchainProvider, since just "cc" is
                  // generic enough to possibly be re-used.
                  .put("cc_provider_in_toolchain", true)
                  .build());

      return new RuleConfiguredTargetBuilder(ruleContext)
          .addProvider(RunfilesProvider.simple(Runfiles.EMPTY))
          .addNativeDeclaredProvider(ccToolchainProvider)
          .addNativeDeclaredProvider(toolchain)
          .addNativeDeclaredProvider(templateVariableInfo)
          .setFilesToBuild(ccToolchainProvider.getAllFilesIncludingLibc())
          .build();
    }
  }
}