// Copyright 2020 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 com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.analysis.RuleContext;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.collect.nestedset.Depset;
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.concurrent.ThreadSafety.Immutable;
import com.google.devtools.build.lib.packages.Info;
import com.google.devtools.build.lib.packages.RuleClass.ConfiguredTargetFactory.RuleErrorException;
import com.google.devtools.build.lib.packages.StarlarkInfo;
import com.google.devtools.build.lib.packages.StarlarkInfoWithSchema;
import com.google.devtools.build.lib.packages.StarlarkProvider;
import com.google.devtools.build.lib.packages.StarlarkProviderWrapper;
import com.google.devtools.build.lib.packages.StructImpl;
import com.google.devtools.build.lib.vfs.PathFragment;
import java.util.Optional;
import net.starlark.java.eval.EvalException;
import net.starlark.java.eval.Starlark;

/** Information about the system APIs for a Java compilation. */
@Immutable
public class BootClassPathInfo extends StarlarkInfoWrapper {

  /** Provider singleton constant. */
  public static final StarlarkProviderWrapper<BootClassPathInfo> PROVIDER = new Provider();

  private static final BootClassPathInfo EMPTY =
      new BootClassPathInfo(null) {
        @Override
        public NestedSet<Artifact> bootclasspath() {
          return NestedSetBuilder.emptySet(Order.STABLE_ORDER);
        }

        @Override
        public NestedSet<Artifact> auxiliary() {
          return NestedSetBuilder.emptySet(Order.STABLE_ORDER);
        }

        @Override
        public NestedSet<Artifact> systemInputs() {
          return NestedSetBuilder.emptySet(Order.STABLE_ORDER);
        }

        @Override
        public Optional<PathFragment> systemPath() {
          return Optional.empty();
        }

        @Override
        public boolean isEmpty() {
          return true;
        }
      };

  public static BootClassPathInfo empty() {
    return EMPTY;
  }

  public static BootClassPathInfo create(RuleContext ruleContext, NestedSet<Artifact> bootclasspath)
      throws RuleErrorException, InterruptedException {
    if (bootclasspath.isEmpty()) {
      return empty();
    }
    ruleContext.initStarlarkRuleContext();
    StructImpl javaCommon = (StructImpl) ruleContext.getStarlarkDefinedBuiltin("java_common");
    try {
      StarlarkProvider starlarkProvider =
          javaCommon.getValue("BootClassPathInfo", StarlarkProvider.class);
      StarlarkInfo starlarkBootClassPathInfo =
          (StarlarkInfo)
              Starlark.call(
                  ruleContext.getStarlarkThread(),
                  starlarkProvider.createRawConstructor(),
                  ImmutableList.of(),
                  ImmutableMap.of("bootclasspath", Depset.of(Artifact.class, bootclasspath)));
      return PROVIDER.wrap(starlarkBootClassPathInfo);
    } catch (EvalException e) {
      throw new RuleErrorException(e);
    }
  }

  private BootClassPathInfo(StructImpl underlying) {
    super(underlying);
  }

  /** The jar files containing classes for system APIs, i.e. a Java <= 8 bootclasspath. */
  public NestedSet<Artifact> bootclasspath() throws RuleErrorException {
    return getUnderlyingNestedSet("bootclasspath", Artifact.class);
  }

  /**
   * The jar files containing extra classes for system APIs that should not be put in the system
   * image to support split-package compilation scenarios.
   */
  public NestedSet<Artifact> auxiliary() throws RuleErrorException {
    return getUnderlyingNestedSet("_auxiliary", Artifact.class);
  }

  /** Contents of the directory that is passed to the javac >= 9 {@code --system} flag. */
  public NestedSet<Artifact> systemInputs() throws RuleErrorException {
    return getUnderlyingNestedSet("_system_inputs", Artifact.class);
  }

  /** An argument to the javac >= 9 {@code --system} flag. */
  public Optional<PathFragment> systemPath() throws RuleErrorException {
    return Optional.ofNullable(getUnderlyingValue("_system_path", String.class))
        .map(PathFragment::create);
  }

  public boolean isEmpty() throws RuleErrorException {
    return bootclasspath().isEmpty()
        && auxiliary().isEmpty()
        && systemInputs().isEmpty()
        && systemPath().isEmpty();
  }

  private static class Provider extends StarlarkProviderWrapper<BootClassPathInfo> {
    private Provider() {
      super(
          Label.parseCanonicalUnchecked("@_builtins//:common/java/boot_class_path_info.bzl"),
          "BootClassPathInfo");
    }

    @Override
    public BootClassPathInfo wrap(Info value) throws RuleErrorException {
      if (value instanceof StarlarkInfoWithSchema
          && value.getProvider().getKey().equals(getKey())) {
        return new BootClassPathInfo((StarlarkInfo) value);
      } else {
        throw new RuleErrorException(
            "got value of type '" + Starlark.type(value) + "', want 'BootClassPathInfo'");
      }
    }
  }
}