// Copyright 2017 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.auto.value.AutoValue;
import com.google.common.collect.ImmutableMap;
import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
import com.google.devtools.build.lib.analysis.RuleContext;
import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
import com.google.devtools.build.lib.packages.BuildType;
import com.google.devtools.build.lib.packages.NonconfigurableAttributeMapper;
import com.google.devtools.build.lib.packages.RuleClass.ConfiguredTargetFactory.RuleErrorException;
import com.google.devtools.build.lib.rules.config.ConfigFeatureFlagProvider;
import java.util.Map;

/**
 * Provider for checking the set of feature flags used by an android_binary.
 *
 * <p>Because the feature flags are completely replaced by android_binary, android_test uses this
 * provider to ensure that the test sets the same flags as the binary. Otherwise, the dependencies
 * of the android_test will be compiled with different flags from the android_binary code which runs
 * in the same Android virtual machine, which may cause compatibility issues at runtime.
 */
@AutoValue
@Immutable
public abstract class AndroidFeatureFlagSetProvider implements TransitiveInfoProvider {

  /** The name of the attribute used by Android rules to set config_feature_flags. */
  public static final String FEATURE_FLAG_ATTR = "feature_flags";

  AndroidFeatureFlagSetProvider() {}

  /** Creates a new AndroidFeatureFlagSetProvider with the given flags. */
  public static AndroidFeatureFlagSetProvider create(Map<Label, String> flags) {
    return new AutoValue_AndroidFeatureFlagSetProvider(ImmutableMap.copyOf(flags));
  }

  /**
   * Builds a map which can be used with create, confirming that the desired flag values were
   * actually received, and producing an error if they were not (because dynamic configurations are
   * not enabled).
   */
  public static ImmutableMap<Label, String> getAndValidateFlagMapFromRuleContext(
      RuleContext ruleContext) throws RuleErrorException {
    Map<Label, String> expectedValues =
        NonconfigurableAttributeMapper.of(ruleContext.getRule())
            .get(FEATURE_FLAG_ATTR, BuildType.LABEL_KEYED_STRING_DICT);
    Iterable<? extends TransitiveInfoCollection> actualTargets =
        ruleContext.getPrerequisites(FEATURE_FLAG_ATTR, Mode.TARGET);
    for (TransitiveInfoCollection target : actualTargets) {
      Label label = target.getLabel();
      String expectedValue = expectedValues.get(label);
      String actualValue = ConfigFeatureFlagProvider.fromTarget(target).getValue();

      if (!expectedValue.equals(actualValue)) {
        // TODO(mstaib): when static configurations are removed, remove this error case
        ruleContext.attributeError(
            FEATURE_FLAG_ATTR,
            "Setting " + FEATURE_FLAG_ATTR + " requires dynamic configurations to be enabled");
        throw new RuleErrorException();
      }
    }
    return ImmutableMap.copyOf(expectedValues);
  }

  public abstract ImmutableMap<Label, String> getFlags();
}