// 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);

         }

 }