// 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.Preconditions.checkNotNull;
import static com.google.devtools.build.lib.analysis.config.BuildConfiguration.StrictDepsMode.OFF;
import static com.google.devtools.build.lib.rules.java.JavaCompilationArgs.ClasspathType.BOTH;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.analysis.RuleContext;
import com.google.devtools.build.lib.analysis.config.BuildConfiguration.StrictDepsMode;
import com.google.devtools.build.lib.collect.nestedset.NestedSet;
import com.google.devtools.build.lib.rules.java.JavaConfiguration.JavaClasspathMode;
import com.google.devtools.build.lib.util.Preconditions;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * A class to create Java compile actions in a way that is consistent with java_library. Rules that
 * generate source files and emulate java_library on top of that should use this class
 * instead of the lower-level API in JavaCompilationHelper.
 *
 * <p>Rules that want to use this class are required to have an implicit dependency on the
 * Java compiler.
 */
public final class JavaLibraryHelper {
  private final RuleContext ruleContext;

  private Artifact output;
  private final List<Artifact> sourceJars = new ArrayList<>();

  /**
   * Contains all the dependencies; these are treated as both compile-time and runtime dependencies.
   */
  private final List<JavaCompilationArgsProvider> deps = new ArrayList<>();
  private ImmutableList<String> javacOpts = ImmutableList.of();

  private StrictDepsMode strictDepsMode = StrictDepsMode.OFF;
  private JavaClasspathMode classpathMode = JavaClasspathMode.OFF;

  public JavaLibraryHelper(RuleContext ruleContext) {
    this.ruleContext = ruleContext;
    ruleContext.getConfiguration();
    this.classpathMode = ruleContext.getFragment(JavaConfiguration.class).getReduceJavaClasspath();
  }

  /**
   * Sets the final output jar; if this is not set, then the {@link #build} method throws an {@link
   * IllegalStateException}. Note that this class may generate not just the output itself, but also
   * a number of additional intermediate files and outputs.
   */
  public JavaLibraryHelper setOutput(Artifact output) {
    this.output = output;
    return this;
  }

  /**
   * Adds the given source jars. Any .java files in these jars will be compiled.
   */
  public JavaLibraryHelper addSourceJars(Iterable<Artifact> sourceJars) {
    Iterables.addAll(this.sourceJars, sourceJars);
    return this;
  }

  /**
   * Adds the given source jars. Any .java files in these jars will be compiled.
   */
  public JavaLibraryHelper addSourceJars(Artifact... sourceJars) {
    return this.addSourceJars(Arrays.asList(sourceJars));
  }

  public JavaLibraryHelper addDep(JavaCompilationArgsProvider provider) {
    checkNotNull(provider);
    this.deps.add(provider);
    return this;
  }

  public JavaLibraryHelper addAllDeps(
      Iterable<JavaCompilationArgsProvider> providers) {
    Iterables.addAll(deps, providers);
    return this;
  }

  /**
   * Sets the compiler options.
   */
  public JavaLibraryHelper setJavacOpts(Iterable<String> javacOpts) {
    this.javacOpts = ImmutableList.copyOf(javacOpts);
    return this;
  }

  /**
   * When in strict mode, compiling the source-jars passed to this JavaLibraryHelper will break if
   * they depend on classes not in any of the {@link
   * JavaCompilationArgsProvider#javaCompilationArgs} passed in {@link #addDep}, even if they do
   * appear in {@link JavaCompilationArgsProvider#recursiveJavaCompilationArgs}. That is, depending
   * on a class requires a direct dependency on it.
   *
   * <p>Contrast this with the strictness-parameter to {@link #buildCompilationArgsProvider}, which
   * controls whether others depending on the result of this compilation, can perform strict-deps
   * checks at all.
   */
  public JavaLibraryHelper setCompilationStrictDepsMode(StrictDepsMode strictDepsMode) {
    this.strictDepsMode = strictDepsMode;
    return this;
  }

  /**
   * Creates the compile actions.
   */
  public JavaCompilationArgs build(
      JavaSemantics semantics,
      JavaToolchainProvider javaToolchainProvider,
      NestedSet<Artifact> hostJavabase,
      Iterable<Artifact> jacocoInstrumental) {
    Preconditions.checkState(output != null, "must have an output file; use setOutput()");
    JavaTargetAttributes.Builder attributes = new JavaTargetAttributes.Builder(semantics);
    attributes.addSourceJars(sourceJars);
    addDepsToAttributes(attributes);
    attributes.setStrictJavaDeps(strictDepsMode);
    attributes.setRuleKind(ruleContext.getRule().getRuleClass());
    attributes.setTargetLabel(ruleContext.getLabel());

    if (isStrict() && classpathMode != JavaClasspathMode.OFF) {
      JavaCompilationHelper.addDependencyArtifactsToAttributes(
          attributes, deps);
    }

    JavaCompilationArtifacts.Builder artifactsBuilder = new JavaCompilationArtifacts.Builder();
    JavaCompilationHelper helper =
        new JavaCompilationHelper(ruleContext, semantics, javacOpts, attributes,
            javaToolchainProvider,
            hostJavabase,
            jacocoInstrumental);
    Artifact outputDepsProto = helper.createOutputDepsProtoArtifact(output, artifactsBuilder);
    helper.createCompileAction(
        output,
        null /* manifestProtoOutput */,
        null /* gensrcOutputJar */,
        outputDepsProto,
        null /* outputMetadata */);
    helper.createCompileTimeJarAction(output, artifactsBuilder);
    artifactsBuilder.addRuntimeJar(output);

    return JavaCompilationArgs.builder().merge(artifactsBuilder.build()).build();
  }

  /**
   * Returns a JavaCompilationArgsProvider that fully encapsulates this compilation, based on the
   * result of a call to build(). (that is, it contains the compile-time and runtime jars, separated
   * by direct vs transitive jars).
   *
   * @param isReportedAsStrict if true, the result's direct JavaCompilationArgs only contain classes
   *     resulting from compiling the source-jars. If false, the direct JavaCompilationArgs contain
   *     both these classes, as well as any classes from transitive dependencies. A value of 'false'
   *     means this compilation cannot be checked for strict-deps, by any consumer (depending)
   *     compilation. Contrast this with {@link #setCompilationStrictDepsMode}.
   */
  public JavaCompilationArgsProvider buildCompilationArgsProvider(
      JavaCompilationArgs directArgs, boolean isReportedAsStrict) {
    JavaCompilationArgs transitiveArgs =
        JavaCompilationArgs.builder()
            .addTransitiveArgs(directArgs, BOTH)
            .addTransitiveDependencies(deps, true /* recursive */)
            .build();

    return JavaCompilationArgsProvider.create(
        isReportedAsStrict ? directArgs : transitiveArgs, transitiveArgs);
  }

  private void addDepsToAttributes(JavaTargetAttributes.Builder attributes) {
    NestedSet<Artifact> directJars;
    if (isStrict()) {
      directJars = getNonRecursiveCompileTimeJarsFromDeps();
      if (directJars != null) {
        attributes.addDirectJars(directJars);
      }
    }

    JavaCompilationArgs args =
        JavaCompilationArgs.builder()
            .addTransitiveDependencies(deps, true)
            .build();
    attributes.addCompileTimeClassPathEntries(args.getCompileTimeJars());
    attributes.addRuntimeClassPathEntries(args.getRuntimeJars());
    attributes.addInstrumentationMetadataEntries(args.getInstrumentationMetadata());
  }

  private NestedSet<Artifact> getNonRecursiveCompileTimeJarsFromDeps() {
    return JavaCompilationArgs.builder()
        .addTransitiveDependencies(deps, false)
        .build()
        .getCompileTimeJars();
  }

  private boolean isStrict() {
    return strictDepsMode != OFF;
  }
}
