content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.datastax.oss.driver.internal.mapper.processor.util;
  
  import java.lang.annotation.Annotation;
  import java.util.Optional;
  import java.util.Set;
  import javax.lang.model.element.Element;
  import javax.lang.model.element.ElementKind;
  import javax.lang.model.element.ExecutableElement;
  import javax.lang.model.element.Modifier;
  import javax.lang.model.element.TypeElement;
  import javax.lang.model.type.TypeKind;
  import javax.lang.model.type.TypeMirror;
  
  public class AnnotationScanner {
    public static <A extends Annotation> Optional<ResolvedAnnotation<A>> getClassAnnotation(
        Class<A> annotationType, Set<TypeElement> typeHierarchy) {
      for (TypeElement element : typeHierarchy) {
        A annotation = element.getAnnotation(annotationType);
        if (annotation != null) {
          return Optional.of(new ResolvedAnnotation<>(annotation, element));
        }
      }
      return Optional.empty();
    }
  
    public static <A extends Annotation> Optional<ResolvedAnnotation<A>> getMethodAnnotation(
        Class<A> annotationType, ExecutableElement getMethod, Set<TypeElement> typeHierarchy) {
      // first try evaluating the method as it is.
      A annotation = getMethod.getAnnotation(annotationType);
      if (annotation != null) {
        return Optional.of(new ResolvedAnnotation<>(annotation, getMethod));
      }
  
      // otherwise navigate the hierarchy until an annotation is found.
      for (TypeElement typeElement : typeHierarchy) {
        for (Element child : typeElement.getEnclosedElements()) {
          Set<Modifier> modifiers = child.getModifiers();
          if (child.getKind() != ElementKind.METHOD
              || modifiers.contains(Modifier.STATIC)
              || modifiers.contains(Modifier.PRIVATE)) {
            continue;
          }
          ExecutableElement candidateMethod = (ExecutableElement) child;
          TypeMirror typeMirror = candidateMethod.getReturnType();
          if (typeMirror.getKind() == TypeKind.VOID) {
            continue;
          }
  
          if (candidateMethod.getSimpleName().equals(getMethod.getSimpleName())) {
            annotation = candidateMethod.getAnnotation(annotationType);
            if (annotation != null) {
              return Optional.of(new ResolvedAnnotation<>(annotation, candidateMethod));
            }
          }
        }
      }
      return Optional.empty();
    }
  }
  