PageableConverter.java

/**
 *   GRANITE DATA SERVICES
 *   Copyright (C) 2006-2015 GRANITE DATA SERVICES S.A.S.
 *
 *   This file is part of the Granite Data Services Platform.
 *
 *   Granite Data Services is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 *
 *   Granite Data Services is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
 *   General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 *   USA, or see <http://www.gnu.org/licenses/>.
 */
package org.granite.spring.data;

import java.lang.reflect.Field;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;

import org.granite.messaging.amf.io.convert.Converter;
import org.granite.messaging.amf.io.convert.Converters;
import org.granite.messaging.amf.io.convert.Reverter;
import org.granite.tide.data.model.PageInfo;
import org.granite.tide.data.model.SortInfo;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.data.domain.Sort.Direction;
import org.springframework.data.domain.Sort.Order;


public class PageableConverter extends Converter implements Reverter {
	
	public PageableConverter(Converters converters) {
		super(converters);
	}

	@Override
	protected boolean internalCanConvert(Object value, Type targetType) {
		return (value instanceof PageInfo && targetType.equals(Pageable.class))
			|| (value instanceof SortInfo && targetType.equals(Sort.class));
	}

	@Override
	protected Object internalConvert(Object value, Type targetType) {
		if (targetType.equals(Pageable.class)) {
			PageInfo pageInfo = (PageInfo)value;
			Sort sort = null;
			if (pageInfo.getSortInfo() != null && pageInfo.getSortInfo().getOrder() != null && pageInfo.getSortInfo().getOrder().length > 0) {
				List<Order> orders = new ArrayList<Order>(pageInfo.getSortInfo().getOrder().length);
				for (int i = 0; i < pageInfo.getSortInfo().getOrder().length; i++)
					orders.add(new Order(pageInfo.getSortInfo().getDesc()[i] ? Direction.DESC : Direction.ASC, pageInfo.getSortInfo().getOrder()[i]));			
				sort = new Sort(orders);			
			}
			return new OffsetPageRequest(pageInfo.getFirstResult(), pageInfo.getMaxResults(), sort);
		}
		return null;
	}

	public boolean canRevert(Object value) {
		return value instanceof Page;
	}

	public Object revert(Object value) {
		@SuppressWarnings("unchecked")
		Page<Object> page = (Page<Object>)value;
		int offset = page.getNumber() * page.getSize();
		try {
			Field f = page.getClass().getDeclaredField("pageable");
			f.setAccessible(true);
			Pageable pageable = (Pageable)f.get(page);
			offset = pageable.getOffset();
		}
		catch (Exception e) {
		}
		return new org.granite.tide.data.model.Page<Object>(offset, page.getSize(), Long.valueOf(page.getTotalElements()).intValue(), page.getContent());
	}
}