/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
package org.hibernate.dialect.pagination;

import org.hibernate.engine.spi.RowSelection;

/**
 * A helper for dealing with LimitHandler implementations
 *
 * @author Lukasz Antoniak (lukasz dot antoniak at gmail dot com)
 */
public class LimitHelper {
	/**
	 * Is a max row limit indicated?
	 *
	 * @param selection The row selection options
	 *
	 * @return Whether a max row limit was indicated
	 */
	public static boolean hasMaxRows(RowSelection selection) {
		return selection != null && selection.getMaxRows() != null && selection.getMaxRows() > 0;
	}

	/**
	 * Should limit be applied?
	 *
	 * @param limitHandler The limit handler
	 * @param selection The row selection
	 *
	 * @return Whether limiting is indicated
	 */
	public static boolean useLimit(LimitHandler limitHandler, RowSelection selection) {
		return limitHandler.supportsLimit() && hasMaxRows( selection );
	}

	/**
	 * Is a first row limit indicated?
	 *
	 * @param selection The row selection options
	 *
	 * @return Whether a first row limit in indicated
	 */
	public static boolean hasFirstRow(RowSelection selection) {
		return getFirstRow( selection ) > 0;
	}

	/**
	 * Retrieve the indicated first row for pagination
	 *
	 * @param selection The row selection options
	 *
	 * @return The first row
	 */
	public static int getFirstRow(RowSelection selection) {
		return ( selection == null || selection.getFirstRow() == null ) ? 0 : selection.getFirstRow();
	}

	private LimitHelper() {
	}
}