// Copyright 2008 Thiago H. de Paula Figueiredo
   //
   // 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 br.com.arsmachina.tapestrycrud.base;
  
  import java.io.Serializable;
  
  import org.apache.tapestry5.ComponentResources;
  import org.apache.tapestry5.EventContext;
  import org.apache.tapestry5.PrimaryKeyEncoder;
  import org.apache.tapestry5.annotations.Cached;
  import org.apache.tapestry5.annotations.OnEvent;
  import org.apache.tapestry5.annotations.PageDetached;
  import org.apache.tapestry5.annotations.Retain;
  import org.apache.tapestry5.beaneditor.BeanModel;
  import org.apache.tapestry5.corelib.components.Grid;
  import org.apache.tapestry5.ioc.annotations.Inject;
  import org.apache.tapestry5.services.BeanModelSource;
  import org.apache.tapestry5.services.Request;
  
  import br.com.arsmachina.tapestrycrud.Constants;
  import br.com.arsmachina.tapestrycrud.grid.ControllerGridDataSource;
  import br.com.arsmachina.tapestrycrud.services.PrimaryKeyEncoderSource;
  
  /**
   * Base class for pages that list entity objects. The <code>object</code> property is meant to be
   * used as the <code>row</code> parameter of the {@link Grid} component.
   * 
   * One example of its use can be found in the Ars Machina Project Example Application (<a
   * href="http://ars-machina.svn.sourceforge.net/viewvc/ars-machina/example/trunk/src/main/java/br/com/arsmachina/example/web/pages/project/ListProject.java?view=markup"
   * >page class</a>. <a
   * href="http://ars-machina.svn.sourceforge.net/viewvc/ars-machina/example/trunk/src/main/webapp/project/ListProject.tml?view=markup"
   * >template</a>).
   * 
   * 
   * @param <T> the entity class related to this encoder.
   * @param <K> the type of the class' primary key property.
   * 
   * @author Thiago H. de Paula Figueiredo
   */
  public abstract class BaseListPage<T, K extends Serializable> extends BasePage<T, K> {
  
  	@Inject
  	private ComponentResources componentResources;
  
  	@Inject
  	private Request request;
  
  	@Inject
  	private PrimaryKeyEncoderSource primaryKeyEncoderSource;
  	
  	@Retain
  	private PrimaryKeyEncoder<K, T> primaryKeyEncoder;
  
  	@Inject
  	private BeanModelSource beanModelSource;
  
  	private T object;
  
  	/**
  	 * Single constructor of this class.
  	 */
  	@SuppressWarnings("unchecked")
  	public BaseListPage() {
  		
  		super();
  		
  		primaryKeyEncoder = (PrimaryKeyEncoder<K, T>) primaryKeyEncoderSource.get(getEntityClass());
  		
  	}
  
  	/**
  	 * Method used as the <code>source</code> parameter of the {@link Grid} component. This
  	 * implementation returns <code>new {@link ControllerGridDataSource}(getController())</code>.
  	 * 
  	 * @return an {@link Object}.
  	 */
  	@SuppressWarnings("unchecked")
  	@Cached
  	public Object getObjects() {
  		return new ControllerGridDataSource(getEntityClass(), getController());
  	}
  
  	/**
  	 * Returns the value of the <code>object</code> property.
  	 * 
  	 * @return a {@link T}.
  	 */
 	public T getObject() {
 		return object;
 	}
 
 	/**
 	 * Changes the value of the <code>object</code> property.
 	 * 
 	 * @param object a {@link T}.
 	 */
 	public void setObject(T object) {
 		this.object = object;
 	}
 
 	/**
 	 * Adds an <code>action</code> property to the {@link BeanModel}.
 	 * 
 	 * @see br.com.arsmachina.tapestrycrud.base.BasePage#getBeanModel()
 	 */
 	@SuppressWarnings("unchecked")
 	public BeanModel<T> getBeanModel() {
 
 		final BeanModel<T> beanModel = beanModelSource.createDisplayModel(getEntityClass(),
 				getMessages());
 		beanModel.add(Constants.ACTION_PROPERTY_NAME, null);
 
 		return beanModel;
 
 	}
 
 	/**
 	 * Removes or not a given object. This method only removes an object, using
 	 * <code>getController().delete(id)</code>, if {@link canRemove(K)} returns <code>true</code>.
 	 * 
 	 * @param object a {@link K}.
 	 */
 	protected final Object remove(T object) {
 		
 		if (object == null) {
 			setRemoveErrorNotFoundMessage();
 		}
 
 		else if (canRemove(object)) {
 
 			getController().delete(object);
 			setRemoveSuccessMessage();
 
 		}
 		else {
 			setRemoveErrorNotAllowedMessage();
 		}
 
 		return returnFromDoRemove();
 
 	}
 
 	/**
 	 * Defines what {@link #doRemove()} will return.
 	 * 
 	 * @return an {@link Object} or <code>null</code>.
 	 */
 	protected Object returnFromDoRemove() {
 
 		Object returnValue = null;
 
 		if (request.isXHR()) {
 
 			if (returnZoneOnXHR()) {
 				returnValue = getFormZone();
 			}
 			else {
 				returnValue = componentResources.getBlock(getFormBlockId());
 			}
 
 		}
 
 		return returnValue;
 
 	}
 
 	/**
 	 * Sets the remove success message in this page.
 	 */
 	protected void setRemoveSuccessMessage() {
 		setMessage(getMessages().get(Constants.MESSAGE_SUCCESS_REMOVE));
 	}
 
 	/**
 	 * Sets the remove not done because of lack of priviledge message in this page.
 	 */
 	protected void setRemoveErrorNotAllowedMessage() {
 		setMessage(getMessages().get(Constants.MESSAGE_ERROR_REMOVE_NOT_ALLOWED));
 	}
 
 	/**
 	 * Sets the remove not done because object not found in this page.
 	 */
 	protected void setRemoveErrorNotFoundMessage() {
 		setMessage(getMessages().get(Constants.MESSAGE_ERROR_REMOVE_NOT_FOUND));
 	}
 
 	/**
 	 * Tells if a given object can be removed in this context. It must be overriden if you have some
 	 * rules about when an object can be removed. This implementation just returns <code>true</code>.
 	 * 
 	 * @param object a {@link #T}.
 	 * @return a <code>boolean</code>.
 	 */
 	protected boolean canRemove(T object) {
 		return true;
 	}
 
 	/**
 	 * Clears the message after it is shown, preventing the message from appearing twice in AJAX
 	 * actions.
 	 */
 	@PageDetached
 	void clearMessage() {
 
 		if (request.isXHR()) {
 			setMessage(null);
 		}
 
 	}
 
 	/**
 	 * This method listens to the {@link Constants#REMOVE_OBJECT_ACTION} event and removes the
 	 * corresponding object.
 	 * 
 	 * @param context an {@link EventContext}.
 	 */
 	@OnEvent(Constants.REMOVE_OBJECT_ACTION)
 	protected Object remove(EventContext context) {
 		
 		K id = context.get(getPrimaryKeyClass(), 0);
 		final T toBeRemoved = primaryKeyEncoder.toValue(id);
 		return remove(toBeRemoved);
 
 	}
 
 	/**
 	 * Returns the configured {@link PrimaryKeyEncoder} for a given entity class.
 	 * 
 	 * @param <X> the type of the entity.
 	 * @param clasz a {@link Class}.
 	 * @return a {@link PrimaryKeyEncoder}.
 	 * @see br.com.arsmachina.tapestrycrud.services.PrimaryKeyEncoderSource#get(java.lang.Class)
 	 */
 	protected <X, Y extends Serializable> PrimaryKeyEncoder<Y, X> getPrimaryKeyEncoder(Class<X> clasz) {
 		return primaryKeyEncoderSource.get(clasz);
 	}
 
 }