// Copyright 2018 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.query2;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;
import com.google.common.collect.Multimap;
import com.google.common.collect.Multimaps;
import com.google.devtools.build.lib.analysis.ConfiguredTarget;
import com.google.devtools.build.lib.analysis.config.ConfigMatchingProvider;
import com.google.devtools.build.lib.analysis.configuredtargets.RuleConfiguredTarget;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.packages.AttributeMap.DepEdge;
import com.google.devtools.build.lib.packages.ConfiguredAttributeMapper;
import com.google.devtools.build.lib.packages.Rule;
import com.google.devtools.build.lib.packages.Target;
import com.google.devtools.build.lib.packages.TargetUtils;
import com.google.devtools.build.lib.query2.aquery.ActionGraphQueryEnvironment;
import com.google.devtools.build.lib.query2.cquery.ConfiguredTargetAccessor;
import com.google.devtools.build.lib.query2.engine.KeyExtractor;
import com.google.devtools.build.lib.query2.engine.QueryEnvironment.TargetAccessor;
import com.google.devtools.build.lib.query2.engine.QueryException;
import com.google.devtools.build.lib.query2.engine.QueryExpression;
import com.google.devtools.build.lib.query2.engine.QueryVisibility;
import com.google.devtools.build.lib.rules.AliasConfiguredTarget;
import com.google.devtools.build.lib.skyframe.AspectValue;
import com.google.devtools.build.lib.skyframe.ConfiguredTargetKey;
import com.google.devtools.build.lib.skyframe.ConfiguredTargetValue;
import com.google.devtools.build.lib.skyframe.SkyFunctions;
import com.google.devtools.build.skyframe.SkyFunctionName;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.WalkableGraph;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * A {@link TargetAccessor} for {@link ConfiguredTargetValue} objects.
 *
 * <p>Incomplete; we'll implement getVisibility when needed.
 */
public class ConfiguredTargetValueAccessor implements TargetAccessor<ConfiguredTargetValue> {

  private final WalkableGraph walkableGraph;
  private final KeyExtractor<ConfiguredTargetValue, ConfiguredTargetKey>
      configuredTargetKeyExtractor;
  private final ActionGraphQueryEnvironment queryEnvironment;

  public ConfiguredTargetValueAccessor(
      WalkableGraph walkableGraph,
      KeyExtractor<ConfiguredTargetValue, ConfiguredTargetKey> configuredTargetKeyExtractor,
      ActionGraphQueryEnvironment queryEnvironment) {
    this.walkableGraph = walkableGraph;
    this.configuredTargetKeyExtractor = configuredTargetKeyExtractor;
    this.queryEnvironment = queryEnvironment;
  }

  @Override
  public String getTargetKind(ConfiguredTargetValue configuredTargetValue) {
    Target actualTarget = getTargetFromConfiguredTargetValue(configuredTargetValue);
    return actualTarget.getTargetKind();
  }

  @Override
  public String getLabel(ConfiguredTargetValue configuredTargetValue) {
    return configuredTargetValue.getConfiguredTarget().getLabel().toString();
  }

  @Override
  public String getPackage(ConfiguredTargetValue configuredTargetValue) {
    return configuredTargetValue
        .getConfiguredTarget()
        .getLabel()
        .getPackageIdentifier()
        .getPackageFragment()
        .toString();
  }

  @Override
  public boolean isRule(ConfiguredTargetValue configuredTargetValue) {
    Target actualTarget = getTargetFromConfiguredTargetValue(configuredTargetValue);
    return actualTarget instanceof Rule;
  }

  @Override
  public boolean isTestRule(ConfiguredTargetValue configuredTargetValue) {
    Target actualTarget = getTargetFromConfiguredTargetValue(configuredTargetValue);
    return TargetUtils.isTestRule(actualTarget);
  }

  @Override
  public boolean isTestSuite(ConfiguredTargetValue configuredTargetValue) {
    Target actualTarget = getTargetFromConfiguredTargetValue(configuredTargetValue);
    return TargetUtils.isTestSuiteRule(actualTarget);
  }

  @Override
  public boolean isAlias(ConfiguredTargetValue configuredTargetValue) {
    Target actualTarget = getTargetFromConfiguredTargetValue(configuredTargetValue);
    return TargetUtils.isAlias(actualTarget);
  }

  private static Label getOriginalLabel(ConfiguredTargetValue configuredTargetValue) {
    ConfiguredTarget configuredTarget = configuredTargetValue.getConfiguredTarget();

    return configuredTarget instanceof AliasConfiguredTarget
        ? ((AliasConfiguredTarget) configuredTarget).getOriginalLabel()
        : configuredTarget.getLabel();
  }

  @Override
  public List<ConfiguredTargetValue> getPrerequisites(
      QueryExpression caller,
      ConfiguredTargetValue configuredTargetValue,
      String attrName,
      String errorMsgPrefix)
      throws InterruptedException {

    ConfiguredTarget configuredTarget = configuredTargetValue.getConfiguredTarget();

    Multimap<Label, ConfiguredTargetValue> depsByLabel =
        Multimaps.index(
            queryEnvironment.getFwdDeps(ImmutableList.of(configuredTargetValue)),
            ConfiguredTargetValueAccessor::getOriginalLabel);

    ImmutableMap<Label, ConfigMatchingProvider> configConditions;
    if (configuredTarget instanceof RuleConfiguredTarget) {
      configConditions = ((RuleConfiguredTarget) configuredTarget).getConfigConditions();
    } else if (configuredTarget instanceof AliasConfiguredTarget) {
      configConditions = ((AliasConfiguredTarget) configuredTarget).getConfigConditions();
    } else {
      throw new IllegalStateException();
    }

    ConfiguredAttributeMapper mapper =
        ConfiguredAttributeMapper.of(
            (Rule) getTargetFromConfiguredTargetValue(configuredTargetValue), configConditions);

    // Doing this with streams results in a type List<? super ConfiguredTargetValue>
    ImmutableList.Builder<ConfiguredTargetValue> result = ImmutableList.builder();
    for (DepEdge depEdge : mapper.visitLabels(mapper.getAttributeDefinition(attrName))) {
      result.addAll(depsByLabel.get(depEdge.getLabel()));
    }

    return result.build();
  }

  @Override
  public List<String> getStringListAttr(
      ConfiguredTargetValue configuredTargetValue, String attrName) {
    Target actualTarget = getTargetFromConfiguredTargetValue(configuredTargetValue);
    return TargetUtils.getStringListAttr(actualTarget, attrName);
  }

  @Override
  public String getStringAttr(ConfiguredTargetValue configuredTargetValue, String attrName) {
    Target actualTarget = getTargetFromConfiguredTargetValue(configuredTargetValue);
    return TargetUtils.getStringAttr(actualTarget, attrName);
  }

  @Override
  public Iterable<String> getAttrAsString(
      ConfiguredTargetValue configuredTargetValue, String attrName) {
    Target actualTarget = getTargetFromConfiguredTargetValue(configuredTargetValue);
    return TargetUtils.getAttrAsString(actualTarget, attrName);
  }

  @Override
  public Set<QueryVisibility<ConfiguredTargetValue>> getVisibility(ConfiguredTargetValue from)
      throws QueryException, InterruptedException {
    // TODO(bazel-team): implement this if needed.
    throw new UnsupportedOperationException();
  }

  private Target getTargetFromConfiguredTargetValue(ConfiguredTargetValue configuredTargetValue) {
    return ConfiguredTargetAccessor.getTargetFromConfiguredTarget(
        configuredTargetValue.getConfiguredTarget(), walkableGraph);
  }

  /** Returns the AspectValues that are attached to the given configuredTarget. */
  public Collection<AspectValue> getAspectValues(ConfiguredTargetValue configuredTargetValue)
      throws InterruptedException {
    Set<AspectValue> result = new HashSet<>();
    SkyKey skyKey = configuredTargetKeyExtractor.extractKey(configuredTargetValue);
    Iterable<SkyKey> revDeps =
        Iterables.concat(walkableGraph.getReverseDeps(ImmutableList.of(skyKey)).values());
    for (SkyKey revDep : revDeps) {
      SkyFunctionName skyFunctionName = revDep.functionName();
      if (SkyFunctions.ASPECT.equals(skyFunctionName)) {
        AspectValue aspectValue = (AspectValue) walkableGraph.getValue(revDep);
        if (aspectValue.getLabel().equals(configuredTargetValue.getConfiguredTarget().getLabel())) {
          result.add(aspectValue);
        }
      }
    }
    return result;
  }
}