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   *  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
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  package org.apache.cayenne.di.spi;
  
  import org.apache.cayenne.di.DIRuntimeException;
  import org.apache.cayenne.di.Provider;
  
  import java.lang.reflect.Type;
  
  /**
   * @since 4.0
   */
  public class ConstructorInjectingDecoratorProvider<T> implements DecoratorProvider<T> {
  
      private Class<? extends T> implementation;
      private DefaultInjector injector;
  
      public ConstructorInjectingDecoratorProvider(Class<? extends T> implementation, DefaultInjector injector) {
          this.implementation = implementation;
          this.injector = injector;
      }
  
      @Override
      public Provider<T> get(final Provider<T> undecorated) throws DIRuntimeException {
  
          return new ConstructorInjectingProvider<T>(implementation, injector) {
              @Override
              protected Object value(Class<?> parameter, Type genericType, String bindingName, InjectionStack stack) {
  
                  // delegate (possibly) injected as Provider
                  if (Provider.class.equals(parameter)) {
  
                      Class<?> objectClass = DIUtil.parameterClass(genericType);
  
                      if (objectClass == null) {
                          throw new DIRuntimeException("Constructor provider parameter %s must be "
                                  + "parameterized to be usable for injection", parameter.getName());
                      }
  
                      if(objectClass.isAssignableFrom(implementation)) {
                          return undecorated;
                      }
                  }
                  // delegate injected as value
                  else if (parameter.isAssignableFrom(implementation)) {
                      return undecorated.get();
                  }
  
                  return super.value(parameter, genericType, bindingName, stack);
              }
          };
      }
  }
  