// Copyright 2015 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.proto;

import static com.google.devtools.build.lib.packages.Attribute.attr;
import static com.google.devtools.build.lib.packages.BuildType.LABEL_LIST;

import com.google.devtools.build.lib.analysis.BaseRuleClasses;
import com.google.devtools.build.lib.analysis.RuleDefinition;
import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
import com.google.devtools.build.lib.packages.RuleClass;
import com.google.devtools.build.lib.packages.RuleClass.Builder;
import com.google.devtools.build.lib.util.FileType;

/**
 * Rule definition for the proto_library rule.
 */
public final class BazelProtoLibraryRule implements RuleDefinition {

  @Override
  public RuleClass build(Builder builder, final RuleDefinitionEnvironment env) {

    return builder
        // This rule works, but does nothing, in open-source Bazel, due to the
        // lack of protoc support. Users can theoretically write their own Skylark rules,
        // but these are still 'experimental' according to the documentation.
        .setUndocumented()
        .setOutputToGenfiles()
        /* <!-- #BLAZE_RULE(proto_library).ATTRIBUTE(deps) -->
        The list of other <code>proto_library</code> rules that the target depends upon.
        ${SYNOPSIS}
        A <code>proto_library</code> may only depend on other
        <code>proto_library</code> targets.
        It may not depend on language-specific libraries.
        <!-- #END_BLAZE_RULE.ATTRIBUTE --> */
        .override(attr("deps", LABEL_LIST)
            .allowedRuleClasses("proto_library")
            .allowedFileTypes())
        /* <!-- #BLAZE_RULE(proto_library).ATTRIBUTE(srcs) -->
        The list of <code>.proto</code> files that are processed to create the target.
        ${SYNOPSIS}
        This is usually a non empty list. One usecase where <code>srcs</code> can be
        empty is an <i>alias-library</i>. This is a proto_library rule having one or
        more other proto_library in <code>deps</code>. This pattern can be used to
        e.g. export a public api under a persistent name.
        <!-- #END_BLAZE_RULE.ATTRIBUTE --> */
        .add(attr("srcs", LABEL_LIST)
            .direct_compile_time_input()
            .allowedFileTypes(FileType.of(".proto")))
        .advertiseProvider(ProtoSourcesProvider.class)
        .build();
  }

  @Override
  public Metadata getMetadata() {
    return RuleDefinition.Metadata.builder()
        .name("proto_library")
        .ancestors(BaseRuleClasses.RuleBase.class)
        .factoryClass(BazelProtoLibrary.class)
        .build();
  }
}

/*<!-- #BLAZE_RULE (NAME = proto_library, TYPE = LIBRARY, FAMILY = Protocol Buffer) -->

${ATTRIBUTE_SIGNATURE}

<p>Use <code>proto_library</code> to define libraries of protocol buffers
   which may be used from multiple languages. A <code>proto_library</code> may be listed
   in the <code>deps</code> clause of supported rules, such as <code>objc_proto_library</code>.
</p>

${ATTRIBUTE_DEFINITION}

<!-- #END_BLAZE_RULE -->*/