// 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.grid;

 import java.util.ArrayList;

 import java.util.List;

 import org.apache.tapestry5.grid.ColumnSort;

 import org.apache.tapestry5.grid.GridDataSource;

 import org.apache.tapestry5.grid.SortConstraint;

 import br.com.arsmachina.controller.Controller;

 import br.com.arsmachina.dao.SortCriterion;

 /**

  * {@link GridDataSource} implementation using a {@link Controller} instance, specifically its

  * {@link Controller#findAll(int, int, SortCriterion[])} method.

  * 

  * @param <T> the type of the elements returned.

  * @author Thiago H. de Paula Figueiredo

  */

 public class PagedSearchGridDataSource<T> implements GridDataSource {

         private static final SortCriterion[] EMPTY_SORT_CRITERION_ARRAY = new SortCriterion[0];

         final private Class<T> entityClass;

         final private PagedSearch<T> pagedSearch;

         private List<T> list;

         private int firstIndex;

         /**

          * Single construtctor of this class.

          * 

          * @param clasz the type of the returned objects. It cannot be null.

          * @param pagedSearch a {@link Controller}. It cannot be null.

          */

         @SuppressWarnings("unchecked")

         public PagedSearchGridDataSource(Class<T> clasz, PagedSearch<T> pagedSearch) {

                 if (pagedSearch == null) {

                         throw new IllegalArgumentException("Parameter pagedSearch cannot be null");

                 }

                 this.pagedSearch = pagedSearch;

                 entityClass = clasz;

                 assert pagedSearch != null;

                 assert entityClass != null;

         }

         public int getAvailableRows() {

                 return pagedSearch.count();

         }

         @SuppressWarnings("unchecked")

         public Class getRowType() {

                 return entityClass;

         }

         public Object getRowValue(int index) {

                 final int position = index - firstIndex;

                 return list.get(position);

         }

         public void prepare(int firstIndex, int endIndex, List<SortConstraint> sortConstraints) {

                 this.firstIndex = firstIndex;

                 SortCriterion[] sortCriteria; 

                 sortCriteria = convertSortConstraintToSortCriterion(sortConstraints);

                 final int maximumResults = (endIndex - firstIndex) + 1;

                 list = pagedSearch.search(firstIndex, maximumResults, sortCriteria);

         }

         /**

          * Converts a {@link List} of {@link SortConstraint} to a {@link SortCriterion} array.

          * @param sortConstraints a {@link List} of {@link SortConstraint}.

          * @return a {@link SortCriterion} array.

          */

         private SortCriterion[] convertSortConstraintToSortCriterion(

                         List<SortConstraint> sortConstraints) {

                 SortCriterion[] sortCriteria;

                 if (sortConstraints.size() > 0) {

                         List<SortCriterion> list = new ArrayList<SortCriterion>();

                         for (SortConstraint sortConstraint : sortConstraints) {

                                 final ColumnSort columnSort = sortConstraint.getColumnSort();

                                 if (columnSort != ColumnSort.UNSORTED) {

                                         final String propertyName = sortConstraint.getPropertyModel().getPropertyName();

                                         final boolean ascending = columnSort == ColumnSort.ASCENDING;

                                         list.add(new SortCriterion(propertyName, ascending));

                                 }

                         }

                         sortCriteria = list.toArray(new SortCriterion[sortConstraints.size()]);

                 }

                 else {

                         sortCriteria = EMPTY_SORT_CRITERION_ARRAY;

                 }

                 return sortCriteria;

         }

 }