/*
    * 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 org.apache.shardingsphere.infra.util.reflection;
  
  import com.google.common.base.CaseFormat;
  import lombok.AccessLevel;
  import lombok.NoArgsConstructor;
  import lombok.SneakyThrows;
  
  import java.lang.reflect.Field;
  import java.lang.reflect.Method;
  import java.util.Optional;
  
  /**
   * Reflection utility class.
   */
  @NoArgsConstructor(access = AccessLevel.PRIVATE)
  public final class ReflectionUtils {
      
      private static final String GETTER_PREFIX = "get";
      
      /**
       * Get field value.
       * 
       * @param target target
       * @param fieldName field name
       * @param <T> type of field value
       * @return field value
       */
      public static <T> Optional<T> getFieldValue(final Object target, final String fieldName) {
          return findField(fieldName, target.getClass()).map(optional -> getFieldValue(target, optional));
      }
      
      @SuppressWarnings("unchecked")
      @SneakyThrows(IllegalAccessException.class)
      private static <T> T getFieldValue(final Object target, final Field field) {
          boolean accessible = field.isAccessible();
          if (!accessible) {
              field.setAccessible(true);
          }
          T result = (T) field.get(target);
          if (!accessible) {
              field.setAccessible(false);
          }
          return result;
      }
      
      private static Optional<Field> findField(final String fieldName, final Class<?> targetClass) {
          Class<?> currentTargetClass = targetClass;
          while (Object.class != currentTargetClass) {
              try {
                  return Optional.of(currentTargetClass.getDeclaredField(fieldName));
              } catch (final NoSuchFieldException ignored) {
                  currentTargetClass = currentTargetClass.getSuperclass();
              }
          }
          return Optional.empty();
      }
      
      /**
       * Get static field value.
       *
       * @param target target
       * @param fieldName field name
       * @param <T> type of field value
       * @return field value
       */
      @SuppressWarnings("unchecked")
      @SneakyThrows(ReflectiveOperationException.class)
      public static <T> T getStaticFieldValue(final Class<?> target, final String fieldName) {
          Field field = target.getDeclaredField(fieldName);
          boolean accessible = field.isAccessible();
          if (!accessible) {
              field.setAccessible(true);
          }
          T result = (T) field.get(target);
          if (!accessible) {
              field.setAccessible(false);
          }
          return result;
      }
      
      /**
       * Set static field value.
      * 
      * @param target target
      * @param fieldName field name
      * @param value value
      */
     @SneakyThrows(ReflectiveOperationException.class)
     public static void setStaticFieldValue(final Class<?> target, final String fieldName, final Object value) {
         Field field = target.getDeclaredField(fieldName);
         boolean accessible = field.isAccessible();
         if (!accessible) {
             field.setAccessible(true);
         }
         field.set(target, value);
         if (!accessible) {
             field.setAccessible(false);
         }
     }
     
     /**
      * Invoke method.
      *
      * @param method method
      * @param target target
      * @param args arguments
      * @param <T> type of invoke result
      * @return invoke result
      */
     @SuppressWarnings("unchecked")
     @SneakyThrows(ReflectiveOperationException.class)
     public static <T> T invokeMethod(final Method method, final Object target, final Object... args) {
         boolean accessible = method.isAccessible();
         if (!accessible) {
             method.setAccessible(true);
         }
         T result = (T) method.invoke(target, args);
         if (!accessible) {
             method.setAccessible(false);
         }
         return result;
     }
     
     /**
      * Get field value by get method.
      *
      * @param target target
      * @param fieldName field name
      * @param <T> type of field value
      * @return field value
      */
     public static <T> Optional<T> getFieldValueByGetMethod(final Object target, final String fieldName) {
         String getterName = GETTER_PREFIX + CaseFormat.LOWER_CAMEL.to(CaseFormat.UPPER_CAMEL, fieldName);
         final Optional<Method> method = findMethod(target.getClass(), getterName);
         if (method.isPresent()) {
             T value = invokeMethod(method.get(), target);
             return Optional.ofNullable(value);
         } else {
             return Optional.empty();
         }
     }
     
     private static Optional<Method> findMethod(final Class<?> clazz, final String methodName, final Class<?>... parameterTypes) {
         try {
             return Optional.of(clazz.getMethod(methodName, parameterTypes));
         } catch (final NoSuchMethodException ex) {
             Class<?> superclass = clazz.getSuperclass();
             if (null != superclass && Object.class != superclass) {
                 return findMethod(superclass, methodName, parameterTypes);
             }
         }
         return Optional.empty();
     }
 }