/*
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * 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.facebook.buck.jvm.java;

import com.facebook.buck.core.model.BuildTarget;
import com.facebook.buck.core.rulekey.AddToRuleKey;
import com.facebook.buck.core.rulekey.AddsToRuleKey;
import com.facebook.buck.core.rules.BuildRule;
import com.facebook.buck.core.rules.SourcePathRuleFinder;
import com.facebook.buck.core.sourcepath.SourcePath;
import com.facebook.buck.jvm.core.JavaLibrary;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.ImmutableSortedSet;
import java.util.Optional;
import javax.annotation.Nullable;

public class JarBackedJavacProvider implements JavacProvider, AddsToRuleKey {
  @AddToRuleKey private final SourcePath javacJarPath;
  @AddToRuleKey private final String compilerClassName;

  // This is just used to cache the Javac derived from the other fields.
  @Nullable private Javac javac;

  public JarBackedJavacProvider(SourcePath javacJarPath, String compilerClassName) {
    this.javacJarPath = javacJarPath;
    this.compilerClassName = compilerClassName;
  }

  @Override
  public Javac resolve(SourcePathRuleFinder ruleFinder) {
    if (javac == null) {
      ImmutableSortedSet.Builder<SourcePath> builder = ImmutableSortedSet.naturalOrder();
      builder.add(javacJarPath);

      // Add transitive deps if any exist so that everything needed is available
      Optional<BuildRule> possibleRule = ruleFinder.getRule(javacJarPath);
      if (possibleRule.isPresent() && possibleRule.get() instanceof JavaLibrary) {
        JavaLibrary compilerLibrary = (JavaLibrary) possibleRule.get();
        builder.addAll(compilerLibrary.getTransitiveClasspaths());
      }

      ImmutableSortedSet<SourcePath> fullJavacClasspath = builder.build();

      javac = new JarBackedJavac(compilerClassName, fullJavacClasspath);
    }

    return javac;
  }

  @Override
  public void addParseTimeDeps(ImmutableCollection.Builder<BuildTarget> depsConsumer) {}

  @Override
  public ImmutableSet<BuildRule> getBuildDeps(SourcePathRuleFinder ruleFinder) {
    return ruleFinder.filterBuildRuleInputs(javacJarPath);
  }
}
