// Copyright 2016 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.android;

import com.google.common.base.Function;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.actions.Artifact;
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.rules.SkylarkApiProvider;
import com.google.devtools.build.lib.rules.android.AndroidResourcesProvider.ResourceContainer;
import com.google.devtools.build.lib.rules.android.AndroidResourcesProvider.ResourceType;
import com.google.devtools.build.lib.rules.java.JavaRuleOutputJarsProvider;
import com.google.devtools.build.lib.rules.java.JavaRuleOutputJarsProvider.OutputJar;
import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;

import javax.annotation.Nullable;

/**
 * A class that exposes the Android providers to Skylark. It is intended to provide a simple and
 * stable interface for Skylark users.
 */
@SkylarkModule(
  name = "AndroidSkylarkApiProvider",
  title = "android",
  category = SkylarkModuleCategory.PROVIDER,
  doc =
      "Provides access to information about Android rules. Every Android-related target provides "
          + "this struct, accessible as a 'android' field on a Target struct."
)
public class AndroidSkylarkApiProvider extends SkylarkApiProvider {
  /** The name of the field in Skylark used to access this class. */
  public static final String NAME = "android";

  private final IdlInfo idlInfo = new IdlInfo();

  @SkylarkCallable(
    name = "apk",
    structField = true,
    allowReturnNones = true,
    doc = "Returns an APK produced by this target."
  )
  public Artifact getApk() {
    return getIdeInfoProvider().getSignedApk();
  }

  private AndroidIdeInfoProvider getIdeInfoProvider() {
    return getInfo().getProvider(AndroidIdeInfoProvider.class);
  }

  @SkylarkCallable(
    name = "java_package",
    structField = true,
    allowReturnNones = true,
    doc = "Returns a java package for this target."
  )
  public String getJavaPackage() {
    return getIdeInfoProvider().getJavaPackage();
  }

  @SkylarkCallable(
    name = "manifest",
    structField = true,
    allowReturnNones = true,
    doc = "Returns a manifest file for this target."
  )
  public Artifact getManifest() {
    return getIdeInfoProvider().getManifest();
  }

  @SkylarkCallable(
      name = "apks_under_test",
      structField = true,
      allowReturnNones = true,
      doc = "Returns a collection of APKs that this target tests."
  )
  public ImmutableCollection<Artifact> getApksUnderTest() {
    return getIdeInfoProvider().getApksUnderTest();
  }

  @SkylarkCallable(
    name = "defines_resources",
    structField = true,
    doc = "Returns true if the target defines any Android resources directly."
  )
  public boolean definesAndroidResources() {
    return getIdeInfoProvider().definesAndroidResources();
  }


  @SkylarkCallable(
      name = "idl",
      structField = true,
      doc = "Returns information about IDL files associated with this target."
  )
  public IdlInfo getIdlInfo() {
    return idlInfo;
  }

  @SkylarkCallable(
    name = "resources",
    structField = true,
    doc = "Returns resources defined by this target."
  )
  public NestedSet<Artifact> getResources() {
    return collectDirectArtifacts(ResourceType.RESOURCES);
  }

  @SkylarkCallable(
      name = "resource_jar",
      structField = true,
      allowReturnNones = true,
      doc = "Returns a jar file for classes generated from resources."
  )
  @Nullable
  public JavaRuleOutputJarsProvider.OutputJar getResourceJar() {
    return getIdeInfoProvider().getResourceJar();
  }

  @SkylarkCallable(
      name = "aar",
      structField = true,
      allowReturnNones = true,
      doc = "Returns the aar output of this target."
  )
  public Artifact getAar() {
    return getIdeInfoProvider().getAar();
  }

  private NestedSet<Artifact> collectDirectArtifacts(final ResourceType resources) {
    AndroidResourcesProvider provider = getInfo().getProvider(AndroidResourcesProvider.class);
    if (provider == null) {
      return NestedSetBuilder.emptySet(Order.STABLE_ORDER);
    }
    // This will iterate over all (direct) resources. If this turns out to be a performance
    // problem, {@link ResourceContainer#getArtifacts} can be changed to return NestedSets.
    return NestedSetBuilder.wrap(
        Order.STABLE_ORDER,
        Iterables.concat(
            Iterables.transform(
                provider.getDirectAndroidResources(),
                new Function<ResourceContainer, Iterable<Artifact>>() {
                  @Override
                  public Iterable<Artifact> apply(ResourceContainer resourceContainer) {
                    return resourceContainer.getArtifacts(resources);
                  }
                })));
  }

  /** Helper class to provide information about IDLs related to this rule. */
  @SkylarkModule(
    name = "AndroidSkylarkIdlInfo",
    category = SkylarkModuleCategory.NONE,
    doc = "Provides access to information about Android rules"
  )
  public class IdlInfo {
    @SkylarkCallable(
        name = "sources",
        structField = true,
        doc = "Returns a list of IDL files."
    )
    public ImmutableCollection<Artifact> getSources() {
      return getIdeInfoProvider().getIdlSrcs();
    }
    @SkylarkCallable(
        name = "generated_java_files",
        structField = true,
        doc = "Returns a list Java files generated from IDL sources."
    )
    public ImmutableCollection<Artifact> getIdlGeneratedJavaFiles() {
      return getIdeInfoProvider().getIdlGeneratedJavaFiles();
    }

    @SkylarkCallable(
        name = "output",
        structField = true,
        allowReturnNones = true,
        doc = "Returns a jar file for classes generated from IDL sources."
    )
    @Nullable
    public JavaRuleOutputJarsProvider.OutputJar getIdlOutput() {
      if (getIdeInfoProvider().getIdlClassJar() == null) {
        return null;
      }

      return new OutputJar(
          getIdeInfoProvider().getIdlClassJar(),
          null,
          getIdeInfoProvider().getIdlSourceJar()
      );
    }
  }
}