/**
    * Copyright 2005-2012 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.uif.field;
  
  import org.apache.commons.lang.StringUtils;
  import org.kuali.rice.core.api.uif.RemotableAttributeField;
  import org.kuali.rice.krad.uif.component.BindingInfo;
  import org.kuali.rice.krad.uif.component.ComponentBase;
  import org.kuali.rice.krad.uif.component.DataBinding;
  import org.kuali.rice.krad.uif.component.MethodInvokerConfig;
  import org.kuali.rice.krad.uif.container.Container;
  import org.kuali.rice.krad.uif.util.CloneUtils;
  import org.kuali.rice.krad.uif.util.ComponentFactory;
  import org.kuali.rice.krad.uif.view.View;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * A placeholder in the configuration for a <code>Container</code> list of items that will be invoked to
   * retrieve a list of {@link RemotableAttributeField} instances which will then be inserted into the containers
   * list at the position of the holder
   *
   * <p>
   * Since remotable fields are dynamic by nature, the individual fields cannot be configured initially with the
   * container. Further more the properties for the field are constructed with code. This gives the ability to specify
   * where that list of fields should be placed, along with configured on how to retrieve the remote fields.
   * </p>
   *
   * <p>
   * The fetching properties are used to configure what method to invoke that will return the list of remotable fields.
   * Specifying the {@link #getFetchingMethodToCall()} only assumes the method is on the view helper service for the
   * contained view. For invoking other classes, such as services or static classes, use {@link
   * #getFetchingMethodInvoker()}
   * </p>
   *
   * <p>
   * The list of remotable fields should bind to a Map property on the model. The {@link #getPropertyName()} and
   * {@link #getBindingInfo()} properties specify the path to this property. The property names configured on the
   * returned fields are assumed to be keys in that above configured map, with the corresponding map value giving the
   * actual model value for the remote field.
   * </p>
   *
   * <p>
   * e.g. configuration
   * {@code
   *    <property name="items">
        <list>
          <bean parent="RemoteFieldsHolder" p:propertyName="remoteFieldValuesMap"
                p:fetchingMethodToCall="retrieveRemoteFields"/>
   *    ...
   * }
   *
   * This example will invoke a method named 'retrieveRemoteFields' on the view helper service, which should return
   * a list of {@link RemotableAttributeField} instances. The view, model instance, and parent container will be sent
   * to the method as arguments.
   *
   * The returned fields will be translated to {@link InputField} instances that bind to a map property named
   * 'remoteFieldValuesMap' on the model.
   * </p>
   *
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public class RemoteFieldsHolder extends ComponentBase implements DataBinding {
      private static final long serialVersionUID = -8493923312021633727L;
      private static final org.apache.log4j.Logger LOG = org.apache.log4j.Logger.getLogger(RemoteFieldsHolder.class);
  
      private String propertyName;
      private BindingInfo bindingInfo;
  
      private String fetchingMethodToCall;
      private MethodInvokerConfig fetchingMethodInvoker;
  
      public RemoteFieldsHolder() {
          super();
      }
  
      /**
       * Invokes the configured fetching method to retrieve a list of remotable fields, then invoked the
       * {@code ComponentFactory} to translate the fields, and finally sets up the binding for the attribute fields
       *
       * @param view - view instance the container belongs to, sent to the fetching method
       * @param model - object containing the view data, sent to the fetching method
       * @param parent - container instance that holder is configured for, sent to the fetching method
       * @return List<AttributeField> list of attribute fields that should be placed into container, if no remotable
       * fields were returned from the fetching method the list will be empty
      */
     public List<InputField> fetchAndTranslateRemoteFields(View view, Object model, Container parent) {
         if (StringUtils.isBlank(fetchingMethodToCall) && (fetchingMethodInvoker == null)) {
             throw new RuntimeException("");
         }
 
         if (fetchingMethodInvoker == null) {
             fetchingMethodInvoker = new MethodInvokerConfig();
         }
 
         // if method not set on invoker, use fetchingMethodToCall, note staticMethod could be set(don't know since
         // there is not a getter), if so it will override the target method in prepare
         if (StringUtils.isBlank(fetchingMethodInvoker.getTargetMethod())) {
             fetchingMethodInvoker.setTargetMethod(fetchingMethodToCall);
         }
 
         // if target class or object not set, use view helper service
         if ((fetchingMethodInvoker.getTargetClass() == null) && (fetchingMethodInvoker.getTargetObject() == null)) {
             fetchingMethodInvoker.setTargetObject(view.getViewHelperService());
         }
 
         Object[] arguments = new Object[3];
         arguments[0] = view;
         arguments[1] = model;
         arguments[2] = parent;
         fetchingMethodInvoker.setArguments(arguments);
 
         // invoke method
         List<RemotableAttributeField> remotableFields = null;
         try {
             LOG.debug("Invoking fetching method: " + fetchingMethodInvoker.getTargetMethod());
             fetchingMethodInvoker.prepare();
 
             remotableFields = (List<RemotableAttributeField>) fetchingMethodInvoker.invoke();
 
         } catch (Exception e) {
             LOG.error("Error invoking fetching method", e);
             throw new RuntimeException("Error invoking fetching method", e);
         }
 
         // do translation
         List<InputField> attributeFields = new ArrayList<InputField>();
         if ((remotableFields != null) && !remotableFields.isEmpty()) {
             attributeFields = ComponentFactory.translateRemotableFields(remotableFields);
         }
 
         // set binding info on the translated fields
         if (bindingInfo == null) {
             bindingInfo = new BindingInfo();
         }
 
         // property name should point to a Map that holds attribute name/value pairs
         bindingInfo.addToBindByNamePrefix(propertyName);
         bindingInfo.setBindToMap(true);
 
         for (InputField field : attributeFields) {
             BindingInfo fieldBindingInfo = CloneUtils.deepClone(bindingInfo);
             fieldBindingInfo.setDefaults(view, field.getPropertyName());
             field.setBindingInfo(fieldBindingInfo);
 
             view.assignComponentIds(field);
         }
 
         return attributeFields;
     }
 
     @Override
     public String getComponentTypeName() {
         return "RemoteFieldsHolder";
     }
 
     /**
      * Path to the Map property that the translated fields bind to
      *
      * <p>
      * It is assumed this property points to a Map where the property names on the returned remotable fields
      * are keys in that map, with the corresponding map value giving the model value for the field
      * </p>
      *
      * @return String path to property on model
      */
     public String getPropertyName() {
         return propertyName;
     }
 
     /**
      * Setter for the property name that points to the binding Map
      *
      * @param propertyName
      */
     public void setPropertyName(String propertyName) {
         this.propertyName = propertyName;
     }
 
     /**
      * Can be used to for more complex binding paths
      *
      * <p>
      * Generally not necessary to set on a field level, any default object path or binding prefixes set
      * on the view or container will be inherited
      * </p>
      *
      * @return BindingInfo instance containing binding information for the Map property
      */
     public BindingInfo getBindingInfo() {
         return bindingInfo;
     }
 
     /**
      * Setter for the Map property binding info instance
      *
      * @param bindingInfo
      */
     public void setBindingInfo(BindingInfo bindingInfo) {
         this.bindingInfo = bindingInfo;
     }
 
     /**
      * Name of the method to invoke for retrieving the list of remotable fields
      *
      * <p>
      * When only the fetching method to call is configured it is assumed to be a valid method on the view
      * helper service for the containing view. The method name must accept the view, model object, and parent
      * container as arguments, and return a list of {@link RemotableAttributeField} instances.
      * </p>
      *
      * <p>
      * For invoking the method on classes other than the view helper service, see {@link #getFetchingMethodInvoker()}
      * </p>
      *
      * @return String name of method to invoke for fetching remote fields
      */
     public String getFetchingMethodToCall() {
         return fetchingMethodToCall;
     }
 
     /**
      * Setter for the fetching method to call
      *
      * @param fetchingMethodToCall
      */
     public void setFetchingMethodToCall(String fetchingMethodToCall) {
         this.fetchingMethodToCall = fetchingMethodToCall;
     }
 
     /**
      * Configuration for the method to invoke for retrieving the list of remotable fields
      *
      * <p>
      * Through the method invoker config, a service or static class can be configured along with the
      * method name that will be invoked. The method name must accept the view, model object, and parent
      * container as arguments, and return a list of {@link RemotableAttributeField} instances.
      * </p>
      *
      * <p>
      * Note the {@link org.kuali.rice.krad.uif.component.MethodInvokerConfig#getTargetMethod()} property can
      * be configured, or the {@link #getFetchingMethodToCall()}. In the case of both configurations, the target
      * method on the method invoker config will be used
      * </p>
      *
      * @return MethodInvokerConfig instance containing method configuration
      */
     public MethodInvokerConfig getFetchingMethodInvoker() {
         return fetchingMethodInvoker;
     }
 
     /**
      * Setter for the fetching method to invoke configuration
      *
      * @param fetchingMethodInvoker
      */
     public void setFetchingMethodInvoker(MethodInvokerConfig fetchingMethodInvoker) {
         this.fetchingMethodInvoker = fetchingMethodInvoker;
     }
 }