// Copyright 2014 Google Inc. 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.analysis;

import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
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.concurrent.ThreadSafety.Immutable;
import com.google.devtools.build.lib.packages.TriState;
import com.google.devtools.build.lib.packages.Type;
import com.google.devtools.build.lib.syntax.Label;
import com.google.devtools.build.lib.vfs.PathFragment;

import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collection;

/**
 * Utility functions for use during analysis.
 */
public final class AnalysisUtils {

  private AnalysisUtils() {
    throw new IllegalStateException(); // utility class
  }

  /**
   * Returns whether link stamping is enabled for a rule.
   *
   * <p>This returns false for unstampable rule classes and for rules in the
   * host configuration. Otherwise it returns the value of the stamp attribute,
   * or of the stamp option if the attribute value is -1.
   */
  public static boolean isStampingEnabled(RuleContext ruleContext) {
    BuildConfiguration config = ruleContext.getConfiguration();
    if (config.isHostConfiguration() || !ruleContext.attributes().has("stamp", Type.TRISTATE)) {
      return false;
    }
    TriState stamp = ruleContext.attributes().get("stamp", Type.TRISTATE);
    return stamp == TriState.YES || (stamp == TriState.AUTO && config.stampBinaries());
  }

  // TODO(bazel-team): These need Iterable<? extends TransitiveInfoCollection> because they need to
  // be called with Iterable<ConfiguredTarget>. Once the configured target lockdown is complete, we
  // can eliminate the "extends" clauses.
  /**
   * Returns the list of providers of the specified type from a set of transitive info
   * collections.
   */
  public static <C extends TransitiveInfoProvider> Iterable<C> getProviders(
      Iterable<? extends TransitiveInfoCollection> prerequisites, Class<C> provider) {
    Collection<C> result = new ArrayList<>();
    for (TransitiveInfoCollection prerequisite : prerequisites) {
      C prerequisiteProvider =  prerequisite.getProvider(provider);
      if (prerequisiteProvider != null) {
        result.add(prerequisiteProvider);
      }
    }
    return ImmutableList.copyOf(result);
  }

  /**
   * Returns the iterable of collections that have the specified provider.
   */
  public static <S extends TransitiveInfoCollection, C extends TransitiveInfoProvider> Iterable<S>
      filterByProvider(Iterable<S> prerequisites, final Class<C> provider) {
    return Iterables.filter(prerequisites, new Predicate<S>() {
      @Override
      public boolean apply(S target) {
        return target.getProvider(provider) != null;
      }
    });
  }

  /**
   * Returns the path of the associated manifest file for the path of a Fileset. Works for both
   * exec paths and root relative paths.
   */
  public static PathFragment getManifestPathFromFilesetPath(PathFragment filesetDir) {
    PathFragment manifestDir = filesetDir.replaceName("_" + filesetDir.getBaseName());
    PathFragment outputManifestFrag = manifestDir.getRelative("MANIFEST");
    return outputManifestFrag;
  }

  /**
   * Returns the middleman artifact on the specified attribute of the specified rule, or an empty
   * set if it does not exist.
   */
  public static NestedSet<Artifact> getMiddlemanFor(RuleContext rule, String attribute) {
    TransitiveInfoCollection prereq = rule.getPrerequisite(attribute, Mode.HOST);
    if (prereq == null) {
      return NestedSetBuilder.emptySet(Order.STABLE_ORDER);
    }
    MiddlemanProvider provider = prereq.getProvider(MiddlemanProvider.class);
    if (provider == null) {
      return NestedSetBuilder.emptySet(Order.STABLE_ORDER);
    }
    return provider.getMiddlemanArtifact();
  }

  /**
   * Returns a path fragment qualified by the rule name and unique fragment to
   * disambiguate artifacts produced from the source file appearing in
   * multiple rules.
   *
   * <p>For example "//pkg:target" -> "pkg/&lt;fragment&gt;/target.
   */
  public static PathFragment getUniqueDirectory(Label label, PathFragment fragment) {
    return label.getPackageFragment().getRelative(fragment)
        .getRelative(label.getName());
  }

  /**
   * Checks that the given provider class either refers to an interface or to a value class.
   */
  public static <T extends TransitiveInfoProvider> void checkProvider(Class<T> clazz) {
    if (!clazz.isInterface()) {
      Preconditions.checkArgument(
          Modifier.isFinal(clazz.getModifiers()), "%s has to be final", clazz.getName());
      Preconditions.checkArgument(clazz.isAnnotationPresent(Immutable.class),
          "%s has to be tagged with @Immutable", clazz.getName());
    }
  }
}