/*
 * Copyright (C) 2014 Google, Inc.
 *
 * 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 dagger.internal.codegen;

import com.google.auto.common.MoreElements;
import com.google.auto.common.MoreTypes;
import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Sets;
import dagger.Component;
import dagger.Module;
import dagger.Subcomponent;
import dagger.producers.ProducerModule;
import dagger.producers.ProductionComponent;
import java.lang.annotation.Annotation;
import java.util.ArrayDeque;
import java.util.List;
import java.util.Queue;
import java.util.Set;
import javax.lang.model.element.AnnotationMirror;
import javax.lang.model.element.AnnotationValue;
import javax.lang.model.element.AnnotationValueVisitor;
import javax.lang.model.element.Element;
import javax.lang.model.element.TypeElement;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.TypeKind;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.util.ElementFilter;
import javax.lang.model.util.Elements;
import javax.lang.model.util.SimpleAnnotationValueVisitor6;
import javax.lang.model.util.SimpleTypeVisitor6;
import javax.lang.model.util.Types;

import static com.google.auto.common.AnnotationMirrors.getAnnotationValue;
import static com.google.auto.common.MoreElements.getAnnotationMirror;
import static com.google.common.base.Preconditions.checkNotNull;

/**
 * Utility methods related to dagger configuration annotations (e.g.: {@link Component}
 * and {@link Module}).
 *
 * @author Gregory Kick
 */
final class ConfigurationAnnotations {

  static boolean isComponent(TypeElement componentDefinitionType) {
    return MoreElements.isAnnotationPresent(componentDefinitionType, Component.class)
        || MoreElements.isAnnotationPresent(componentDefinitionType, ProductionComponent.class);
  }

  private static final String MODULES_ATTRIBUTE = "modules";

  static ImmutableList<TypeMirror> getComponentModules(AnnotationMirror componentAnnotation) {
    checkNotNull(componentAnnotation);
    return convertClassArrayToListOfTypes(componentAnnotation, MODULES_ATTRIBUTE);
  }

  private static final String DEPENDENCIES_ATTRIBUTE = "dependencies";

  static ImmutableList<TypeMirror> getComponentDependencies(AnnotationMirror componentAnnotation) {
    checkNotNull(componentAnnotation);
    return convertClassArrayToListOfTypes(componentAnnotation, DEPENDENCIES_ATTRIBUTE);
  }

  private static final String INCLUDES_ATTRIBUTE = "includes";

  static ImmutableList<TypeMirror> getModuleIncludes(AnnotationMirror moduleAnnotation) {
    checkNotNull(moduleAnnotation);
    return convertClassArrayToListOfTypes(moduleAnnotation, INCLUDES_ATTRIBUTE);
  }

  private static final String INJECTS_ATTRIBUTE = "injects";

  static ImmutableList<TypeMirror> getModuleInjects(AnnotationMirror moduleAnnotation) {
    checkNotNull(moduleAnnotation);
    return convertClassArrayToListOfTypes(moduleAnnotation, INJECTS_ATTRIBUTE);
  }

  /** Returns the first type that specifies this' nullability, or absent if none. */
  static Optional<DeclaredType> getNullableType(Element element) {
    List<? extends AnnotationMirror> mirrors = element.getAnnotationMirrors();
    for (AnnotationMirror mirror : mirrors) {
      if (mirror.getAnnotationType().asElement().getSimpleName().toString().equals("Nullable")) {
        return Optional.of(mirror.getAnnotationType());
      }
    }
    return Optional.absent();
  }

  /**
   * Extracts the list of types that is the value of the annotation member {@code elementName} of
   * {@code annotationMirror}.
   *
   * @throws IllegalArgumentException if no such member exists on {@code annotationMirror}, or it
   *     exists but is not an array
   * @throws TypeNotPresentException if any of the values cannot be converted to a type
   */
  static ImmutableList<TypeMirror> convertClassArrayToListOfTypes(
      AnnotationMirror annotationMirror, String elementName) {
    return TO_LIST_OF_TYPES.visit(getAnnotationValue(annotationMirror, elementName), elementName);
  }

  private static final AnnotationValueVisitor<ImmutableList<TypeMirror>, String> TO_LIST_OF_TYPES =
      new SimpleAnnotationValueVisitor6<ImmutableList<TypeMirror>, String>() {
        @Override
        public ImmutableList<TypeMirror> visitArray(
            List<? extends AnnotationValue> vals, String elementName) {
          return FluentIterable.from(vals)
              .transform(
                  new Function<AnnotationValue, TypeMirror>() {
                    @Override
                    public TypeMirror apply(AnnotationValue typeValue) {
                      return TO_TYPE.visit(typeValue);
                    }
                  })
              .toList();
        }

        @Override
        protected ImmutableList<TypeMirror> defaultAction(Object o, String elementName) {
          throw new IllegalArgumentException(elementName + " is not an array: " + o);
        }
      };

  private static final AnnotationValueVisitor<TypeMirror, Void> TO_TYPE =
      new SimpleAnnotationValueVisitor6<TypeMirror, Void>() {
        @Override
        public TypeMirror visitType(TypeMirror t, Void p) {
          return t;
        }

        @Override
        protected TypeMirror defaultAction(Object o, Void p) {
          throw new TypeNotPresentException(o.toString(), null);
        }
      };

  /**
   * Returns the full set of modules transitively {@linkplain Module#includes included} from the
   * given seed modules.  If a module is malformed and a type listed in {@link Module#includes}
   * is not annotated with {@link Module}, it is ignored.
   *
   * @deprecated Use {@link ComponentDescriptor#transitiveModules}.
   */
  @Deprecated
  static ImmutableSet<TypeElement> getTransitiveModules(
      Types types, Elements elements, Iterable<TypeElement> seedModules) {
    TypeMirror objectType = elements.getTypeElement(Object.class.getCanonicalName()).asType();
    Queue<TypeElement> moduleQueue = new ArrayDeque<>();
    Iterables.addAll(moduleQueue, seedModules);
    Set<TypeElement> moduleElements = Sets.newLinkedHashSet();
    for (TypeElement moduleElement = moduleQueue.poll();
        moduleElement != null;
        moduleElement = moduleQueue.poll()) {
      Optional<AnnotationMirror> moduleMirror = getAnnotationMirror(moduleElement, Module.class)
          .or(getAnnotationMirror(moduleElement, ProducerModule.class));
      if (moduleMirror.isPresent()) {
        ImmutableSet.Builder<TypeElement> moduleDependenciesBuilder = ImmutableSet.builder();
        moduleDependenciesBuilder.addAll(
            MoreTypes.asTypeElements(getModuleIncludes(moduleMirror.get())));
        // (note: we don't recurse on the parent class because we don't want the parent class as a
        // root that the component depends on, and also because we want the dependencies rooted
        // against this element, not the parent.)
        addIncludesFromSuperclasses(types, moduleElement, moduleDependenciesBuilder, objectType);
        ImmutableSet<TypeElement> moduleDependencies = moduleDependenciesBuilder.build();
        moduleElements.add(moduleElement);
        for (TypeElement dependencyType : moduleDependencies) {
          if (!moduleElements.contains(dependencyType)) {
            moduleQueue.add(dependencyType);
          }
        }
      }
    }
    return ImmutableSet.copyOf(moduleElements);
  }

  /** Returns the enclosed elements annotated with the given annotation type. */
  static ImmutableList<DeclaredType> enclosedBuilders(TypeElement typeElement,
      final Class<? extends Annotation> annotation) {
    final ImmutableList.Builder<DeclaredType> builders = ImmutableList.builder();
    for (TypeElement element : ElementFilter.typesIn(typeElement.getEnclosedElements())) {
      if (MoreElements.isAnnotationPresent(element, annotation)) {
        builders.add(MoreTypes.asDeclared(element.asType()));
      }
    }
    return builders.build();
  }

  static boolean isSubcomponentType(TypeMirror type) {
    return type.accept(new SubcomponentDetector(), null).isPresent();
  }

  private static final class SubcomponentDetector
      extends SimpleTypeVisitor6<Optional<AnnotationMirror>, Void> {
    @Override
    protected Optional<AnnotationMirror> defaultAction(TypeMirror e, Void p) {
      return Optional.absent();
    }

    @Override
    public Optional<AnnotationMirror> visitDeclared(DeclaredType t, Void p) {
      return MoreElements.getAnnotationMirror(t.asElement(), Subcomponent.class);
    }
  }

  /** Traverses includes from superclasses and adds them into the builder. */
  private static void addIncludesFromSuperclasses(Types types, TypeElement element,
      ImmutableSet.Builder<TypeElement> builder, TypeMirror objectType) {
    // Also add the superclass to the queue, in case any @Module definitions were on that.
    TypeMirror superclass = element.getSuperclass();
    while (!types.isSameType(objectType, superclass)
        && superclass.getKind().equals(TypeKind.DECLARED)) {
      element = MoreElements.asType(types.asElement(superclass));
      Optional<AnnotationMirror> moduleMirror = getAnnotationMirror(element, Module.class)
          .or(getAnnotationMirror(element, ProducerModule.class));
      if (moduleMirror.isPresent()) {
        builder.addAll(MoreTypes.asTypeElements(getModuleIncludes(moduleMirror.get())));
      }
      superclass = element.getSuperclass();
    }
  }

  private ConfigurationAnnotations() {}
}