// 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.rules.java;

import static com.google.common.base.Strings.isNullOrEmpty;

import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableList.Builder;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableMap;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.analysis.AliasProvider;
import com.google.devtools.build.lib.analysis.ConfiguredTarget;
import com.google.devtools.build.lib.analysis.FilesToRunProvider;
import com.google.devtools.build.lib.analysis.PrerequisiteArtifacts;
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.Runfiles;
import com.google.devtools.build.lib.analysis.RunfilesProvider;
import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
import com.google.devtools.build.lib.analysis.configuredtargets.RuleConfiguredTarget.Mode;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.collect.nestedset.NestedSet;
import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
import com.google.devtools.build.lib.collect.nestedset.Order;
import com.google.devtools.build.lib.syntax.Type;
import java.util.List;
import java.util.Map;

/**
 * Implementation for the {@code java_toolchain} rule.
 */
public final class JavaToolchain implements RuleConfiguredTargetFactory {

  @Override
  public ConfiguredTarget create(RuleContext ruleContext) throws RuleErrorException {
    ImmutableList<String> javacopts = getJavacOpts(ruleContext);
    NestedSet<Artifact> bootclasspath = PrerequisiteArtifacts.nestedSet(
        ruleContext, "bootclasspath", Mode.HOST);
    NestedSet<Artifact> extclasspath = PrerequisiteArtifacts.nestedSet(
        ruleContext, "extclasspath", Mode.HOST);
    boolean javacSupportsWorkers =
        ruleContext.attributes().get("javac_supports_workers", Type.BOOLEAN);
    Artifact javac = ruleContext.getPrerequisiteArtifact("javac", Mode.HOST);
    FilesToRunProvider javabuilder =
        ruleContext.getExecutablePrerequisite("javabuilder", Mode.HOST);
    Artifact headerCompiler = ruleContext.getPrerequisiteArtifact("header_compiler", Mode.HOST);
    boolean forciblyDisableHeaderCompilation =
        ruleContext.attributes().get("forcibly_disable_header_compilation", Type.BOOLEAN);
    Artifact singleJar = ruleContext.getPrerequisiteArtifact("singlejar", Mode.HOST);
    Artifact oneVersion = ruleContext.getPrerequisiteArtifact("oneversion", Mode.HOST);
    Artifact oneVersionWhitelist = ruleContext
        .getPrerequisiteArtifact("oneversion_whitelist", Mode.HOST);
    Artifact genClass = ruleContext.getPrerequisiteArtifact("genclass", Mode.HOST);
    Artifact resourceJarBuilder = ruleContext.getPrerequisiteArtifact("resourcejar", Mode.HOST);
    Artifact timezoneData = ruleContext.getPrerequisiteArtifact("timezone_data", Mode.HOST);
    FilesToRunProvider ijar = ruleContext.getExecutablePrerequisite("ijar", Mode.HOST);
    ImmutableListMultimap<String, String> compatibleJavacOptions =
        getCompatibleJavacOptions(ruleContext);

    NestedSet<Artifact> tools = PrerequisiteArtifacts.nestedSet(ruleContext, "tools", Mode.HOST);

    TransitiveInfoCollection javacDep = ruleContext.getPrerequisite("javac", Mode.HOST);
    ImmutableList<String> jvmOpts =
        getJvmOpts(
            ruleContext,
            ImmutableMap.<Label, ImmutableCollection<Artifact>>of(
                AliasProvider.getDependencyLabel(javacDep), ImmutableList.of(javac)));

    ImmutableList<JavaPackageConfigurationProvider> packageConfiguration =
        ImmutableList.copyOf(
            ruleContext.getPrerequisites(
                "package_configuration", Mode.HOST, JavaPackageConfigurationProvider.class));

    JavaConfiguration configuration = ruleContext.getFragment(JavaConfiguration.class);
    JavaToolchainProvider provider =
        JavaToolchainProvider.create(
            ruleContext.getLabel(),
            javacopts,
            jvmOpts,
            javacSupportsWorkers,
            bootclasspath,
            extclasspath,
            configuration.getDefaultJavacFlags(),
            javac,
            tools,
            javabuilder,
            headerCompiler,
            forciblyDisableHeaderCompilation,
            singleJar,
            oneVersion,
            oneVersionWhitelist,
            genClass,
            resourceJarBuilder,
            timezoneData,
            ijar,
            compatibleJavacOptions,
            packageConfiguration);
    RuleConfiguredTargetBuilder builder =
        new RuleConfiguredTargetBuilder(ruleContext)
            .addSkylarkTransitiveInfo(
                JavaToolchainSkylarkApiProvider.NAME, new JavaToolchainSkylarkApiProvider())
            .addNativeDeclaredProvider(provider)
            .addProvider(RunfilesProvider.class, RunfilesProvider.simple(Runfiles.EMPTY))
            .setFilesToBuild(new NestedSetBuilder<Artifact>(Order.STABLE_ORDER).build());

    return builder.build();
  }

  private ImmutableList<String> getJavacOpts(RuleContext ruleContext) {
    Builder<String> javacopts = ImmutableList.builder();
    String source = ruleContext.attributes().get("source_version", Type.STRING);
    if (!isNullOrEmpty(source)) {
      javacopts.add("-source").add(source);
    }
    String target = ruleContext.attributes().get("target_version", Type.STRING);
    if (!isNullOrEmpty(target)) {
      javacopts.add("-target").add(target);
    }
    String encoding = ruleContext.attributes().get("encoding", Type.STRING);
    if (!isNullOrEmpty(encoding)) {
      javacopts.add("-encoding", encoding);
    }
    List<String> xlint = ruleContext.attributes().get("xlint", Type.STRING_LIST);
    if (!xlint.isEmpty()) {
      javacopts.add("-Xlint:" + Joiner.on(",").join(xlint));
    }
    javacopts.addAll(ruleContext.getExpander().withDataLocations().tokenized("misc"));
    javacopts.addAll(ruleContext.getExpander().withDataLocations().tokenized("javacopts"));
    return javacopts.build();
  }

  private static ImmutableListMultimap<String, String> getCompatibleJavacOptions(
      RuleContext ruleContext) {
    ImmutableListMultimap.Builder<String, String> result = ImmutableListMultimap.builder();
    for (Map.Entry<String, List<String>> entry :
        ruleContext.attributes().get("compatible_javacopts", Type.STRING_LIST_DICT).entrySet()) {
      result.putAll(entry.getKey(), JavaHelper.tokenizeJavaOptions(entry.getValue()));
    }
    return result.build();
  }

  private static ImmutableList<String> getJvmOpts(
      RuleContext ruleContext, ImmutableMap<Label, ImmutableCollection<Artifact>> locations) {
    return ruleContext.getExpander().withExecLocations(locations).list("jvm_opts");
  }
}
