/**
    * Copyright 2005-2015 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.rice.krad.web.controller;
  
  import org.kuali.rice.krad.uif.UifConstants;
  import org.kuali.rice.krad.web.form.UifFormBase;
  import org.springframework.core.MethodParameter;
  import org.springframework.validation.BindException;
  import org.springframework.validation.Errors;
  import org.springframework.web.bind.ServletRequestDataBinder;
  import org.springframework.web.bind.WebDataBinder;
  import org.springframework.web.bind.annotation.ModelAttribute;
  import org.springframework.web.bind.support.WebDataBinderFactory;
  import org.springframework.web.context.request.NativeWebRequest;
  import org.springframework.web.method.support.HandlerMethodArgumentResolver;
  import org.springframework.web.method.support.ModelAndViewContainer;
  
  import javax.servlet.ServletRequest;
  import java.util.Map;
  
  /**
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public class UifDefaultFormMethodArgumentResolver implements HandlerMethodArgumentResolver {
  
      /**
       * Default Constructor.
       */
      public UifDefaultFormMethodArgumentResolver() {
          super();
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public boolean supportsParameter(MethodParameter parameter) {
          boolean isUifForm = false;
  
          if (!parameter.hasParameterAnnotation(ModelAttribute.class) && UifFormBase.class.isAssignableFrom(
                  parameter.getParameterType())) {
              isUifForm = true;
          }
  
          return isUifForm;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
              NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
          String name = UifConstants.DEFAULT_MODEL_NAME;
  
          Object attribute = null;
          if (mavContainer.containsAttribute(name)) {
              attribute = mavContainer.getModel().get(name);
          }
  
          WebDataBinder binder = binderFactory.createBinder(webRequest, attribute, name);
          if (binder.getTarget() != null) {
              ServletRequest servletRequest = webRequest.getNativeRequest(ServletRequest.class);
              ServletRequestDataBinder servletBinder = (ServletRequestDataBinder) binder;
              servletBinder.bind(servletRequest);
  
              if (binder.getBindingResult().hasErrors()) {
                  if (isBindExceptionRequired(parameter)) {
                      throw new BindException(binder.getBindingResult());
                  }
              }
          }
  
          Map<String, Object> bindingResultModel = binder.getBindingResult().getModel();
          mavContainer.removeAttributes(bindingResultModel);
          mavContainer.addAllAttributes(bindingResultModel);
  
          return binder.getTarget();
      }
  
      /**
       * Whether to raise a {@link BindException} on validation errors.
       *
       * @param parameter the method argument
       * @return {@code true} if the next method argument is not of type {@link org.springframework.validation.Errors}.
       */
     protected boolean isBindExceptionRequired(MethodParameter parameter) {
         int i = parameter.getParameterIndex();
         Class<?>[] paramTypes = parameter.getMethod().getParameterTypes();
         boolean hasBindingResult = (paramTypes.length > (i + 1) && Errors.class.isAssignableFrom(paramTypes[i + 1]));
 
         return !hasBindingResult;
     }
 
 }