// 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.repository;

import com.google.common.collect.ImmutableMap;
import com.google.devtools.build.lib.analysis.ConfiguredTarget;
import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
import com.google.devtools.build.lib.analysis.RuleContext;
import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
import com.google.devtools.build.lib.packages.RuleClass.ConfiguredTargetFactory.RuleErrorException;
import com.google.devtools.build.lib.rules.AliasConfiguredTarget;
import com.google.devtools.build.lib.rules.AliasProvider;
import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;

/**
 * Implementation for the bind rule.
 */
public class Bind implements RuleConfiguredTargetFactory {

  @Override
  public ConfiguredTarget create(RuleContext ruleContext)
      throws InterruptedException, RuleErrorException {
    if (ruleContext.getPrerequisite("actual", Mode.TARGET) == null) {
      ruleContext.ruleError(String.format("The external label '%s' is not bound to anything",
          ruleContext.getLabel()));
      return null;
    }

    ConfiguredTarget actual = (ConfiguredTarget) ruleContext.getPrerequisite("actual", Mode.TARGET);
    return new AliasConfiguredTarget(
        ruleContext.getConfiguration(),
        actual,
        ImmutableMap.<Class<? extends TransitiveInfoProvider>, TransitiveInfoProvider>of(
            AliasProvider.class, AliasProvider.fromAliasRule(ruleContext.getLabel(), actual)));
  }
}
