/**
    * This file Copyright (c) 2011 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.objectfactory;
  
  import java.lang.reflect.Constructor;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Modifier;
  import javax.inject.Inject;
  
  
  
  /**
   * Creates objects by dynamically resolving the parameters to use.
   *
   * @version $Id$
   */
  public class ObjectManufacturer {
  
      /**
       * Creates an object of the given type using parameters provided by a set of parameter resolvers. Will first look
       * for a constructor annotated with @Inject, it can be public, private, protected or package private. It will
       * then look at public constructors and use the greediest. The greediest constructor is the one that has the most
       * number of arguments that the parameter resolvers can fulfill. If there is more than one constructor that
       * qualifies as greediest it is unspecified which one will be used.
       */
      public Object newInstance(Class<?> clazz, ParameterResolver... parameterResolvers) {
  
          Constructor<?>[] constructors = clazz.getDeclaredConstructors();
  
          Constructor<?> selectedConstructor = null;
          for (Constructor<?> constructor : constructors) {
              if (constructor.isAnnotationPresent(Inject.class)) {
                  if (selectedConstructor != null) {
                      throw new MgnlInstantiationException("Only one constructor can use @Inject [" + clazz + "]");
                  }
                  selectedConstructor = constructor;
              }
          }
          if (selectedConstructor != null) {
              selectedConstructor.setAccessible(true);
              Object[] parameters = resolveParameters(selectedConstructor, parameterResolvers);
              if (parameters == null) {
                  throw new MgnlInstantiationException("Unable to resolve parameters for constructor " + selectedConstructor);
              }
              return newInstance(selectedConstructor, parameters);
          }
  
          // Find greediest satisfiable constructor
          int bestScore = -1;
          Object[] bestParameters = null;
          for (Constructor<?> constructor : constructors) {
              if (!Modifier.isPublic(constructor.getModifiers())) {
                  continue;
              }
              int score = constructor.getParameterTypes().length;
              if (score < bestScore) {
                  continue;
              }
              Object[] parameters = resolveParameters(constructor, parameterResolvers);
              if (parameters == null) {
                  continue;
              }
              selectedConstructor = constructor;
              bestScore = score;
              bestParameters = parameters;
          }
          if (selectedConstructor != null) {
              return newInstance(selectedConstructor, bestParameters);
         }
         throw new MgnlInstantiationException("No suitable constructor found for class [" + clazz + "]");
     }
 
     private Object newInstance(Constructor constructor, Object[] parameters) {
         try {
             return constructor.newInstance(parameters);
         } catch (InstantiationException e) {
             throw new MgnlInstantiationException(e);
         } catch (IllegalAccessException e) {
             throw new MgnlInstantiationException(e);
         } catch (InvocationTargetException e) {
             throw new MgnlInstantiationException(e);
         }
     }
 
     private Object[] resolveParameters(Constructor<?> constructor, ParameterResolver[] parameterResolvers) {
         Object[] parameters = new Object[constructor.getParameterTypes().length];
         for (int parameterIndex = 0; parameterIndex < parameters.length; parameterIndex++) {
             ParameterInfo constructorParameter = new ParameterInfo(constructor, parameterIndex);
             Object parameter = resolveParameter(constructorParameter, parameterResolvers);
             if (parameter == ParameterResolver.UNRESOLVED) {
                 return null;
             }
             parameters[parameterIndex] = parameter;
         }
         return parameters;
     }
 
     private Object resolveParameter(ParameterInfo constructorParameter, ParameterResolver[] parameterResolvers) {
         for (ParameterResolver parameterResolver : parameterResolvers) {
             Object parameter = parameterResolver.resolveParameter(constructorParameter);
             if (parameter != ParameterResolver.UNRESOLVED) {
                 return parameter;
             }
         }
         return ParameterResolver.UNRESOLVED;
     }
 
 }