/*
    * Copyright 2016 Function1. 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 tools.gsf.config.inject;
  
  import org.apache.commons.lang3.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.beans.BeanUtils;
  import tools.gsf.config.Factory;
  
  import java.lang.reflect.Field;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  
  /**
   * @author Tony Field
   * @since 2016-07-21
   */
  public final class InjectForRequestInjector implements Injector {
      private static final Logger LOG = LoggerFactory.getLogger("tools.gsf.config.inject.InjectForRequestInjector");
  
      private final Factory factory;
  
      public InjectForRequestInjector(Factory factory) {
          this.factory = factory;
      }
  
      /**
       * Inject ICS runtime objects into the object. Objects flagged with the
       * {@link InjectForRequest} annotation will be populated by this method by
       * retrieving the value from the {@link Factory#getObject(String, Class)}
       * method.
       *
       * @param dependent the object to inject into
       */
      public void inject(final Object dependent) {
          if (dependent == null) {
              throw new IllegalArgumentException("dependent cannot be null.");
          }
  
          Class<?> c = dependent.getClass();
          // first to all annotated public setter methods.
          for (final Method method : c.getMethods()) {
              if (method.isAnnotationPresent(InjectForRequest.class)) {
                  injectIntoMethod(dependent, factory, method);
              }
          }
          // and then all annotated fields.
          while (c != Object.class && c != null) {
              for (final Field field : c.getDeclaredFields()) {
                  if (field.isAnnotationPresent(InjectForRequest.class)) {
                      injectIntoField(dependent, factory, field);
                  }
              }
              c = c.getSuperclass();
          }
      }
  
      /**
       * @param object  the object to inject into
       * @param factory the factory that created the objects that need to be
       *                injected.
       * @param field   field to inject into
       * @throws SecurityException security exception injecting values into field
       */
      private static void injectIntoField(final Object object, final Factory factory, final Field field) throws SecurityException {
  
          final InjectForRequest ifr = field.getAnnotation(InjectForRequest.class);
  
          String name = ifr.value();
          if (StringUtils.isBlank(name)) {
              name = field.getName();
          }
          final Object injectionValue = factory.getObject(name, field.getType());
          if (injectionValue == null) {
              throw new InjectionException(factory.getClass().getName() + " does not know how to inject '" + field.getType().getName() + "' into the field '" + field.getName() + "' of object " + object.hashCode() + " (" + object.getClass().getName() + ").");
          }
          field.setAccessible(true); // make private fields accessible
          LOG.debug("Injecting {} into field {} for {}", injectionValue.getClass().getName(), field.getName(), object.getClass().getName());
          try {
              field.set(object, injectionValue);
          } catch (final IllegalArgumentException e) {
              throw new InjectionException("IllegalArgumentException injecting " + injectionValue + " into field " + field.getName(), e);
          } catch (final IllegalAccessException e) {
              throw new InjectionException("IllegalAccessException injecting " + injectionValue + " into field " + field.getName(), e);
          }
     }
 
     /**
      * @param object  the object to inject into
      * @param factory the factory that created the objects that need to be
      *                injected.
      * @param method  the method to inject into
      * @throws SecurityException security exception when injecting value into field
      */
     private static void injectIntoMethod(final Object object, final Factory factory, final Method method) throws SecurityException {
         final InjectForRequest ifr = method.getAnnotation(InjectForRequest.class);
 
         String name = ifr.value();
         if (StringUtils.isBlank(name)) {
             name = BeanUtils.findPropertyForMethod(method).getName();
         }
 
         final Class<?> type = method.getParameterTypes()[0];
         final Object injectionValue = factory.getObject(name, type);
         if (injectionValue == null) {
             throw new InjectionException(factory.getClass().getName() + " does not know how to inject '" + type.getName() + "' into the method '" + method.getName() + "' of object " + object.hashCode() + " (" + object.getClass().getName() + ").");
         }
 
         // accessible
         LOG.debug("Injecting {} into field {} for {}", injectionValue.getClass().getName(), method.getName(), object.getClass().getName());
         try {
             method.invoke(object, injectionValue);
         } catch (final IllegalArgumentException e) {
             throw new InjectionException("IllegalArgumentException injecting " + injectionValue + " into method " + method.getName(), e);
         } catch (final IllegalAccessException e) {
             throw new InjectionException("IllegalAccessException injecting " + injectionValue + " into method " + method.getName(), e);
         } catch (final InvocationTargetException e) {
             throw new InjectionException("InvocationTargetException injecting " + injectionValue + " into method " + method.getName(), e);
         }
     }
 }