package com.eds.adf.domainstore.interceptor;

import org.apache.commons.lang.StringUtils;
import org.hibernate.EmptyInterceptor;

/**
 * Created by IntelliJ IDEA.
 * User: zzy9v4
 * Date: 23-feb-2007
 * Time: 10.39.27
 * To change this template use File | Settings | File Templates.
 */
public class CustomNullsFirstInterceptor extends EmptyInterceptor {
	
	private static final long serialVersionUID = -3156853534261313031L;
	
	private static final String ORDER_BY_TOKEN = "order by";

	public String onPrepareStatement(String sql) {
		
		int orderByStart = sql.toLowerCase().indexOf(ORDER_BY_TOKEN);
		if (orderByStart == -1) {
			return super.onPrepareStatement(sql);
		}
		orderByStart += ORDER_BY_TOKEN.length() + 1;
		int orderByEnd = sql.indexOf(")", orderByStart);
		if (orderByEnd == -1) {
			orderByEnd = sql.indexOf(" UNION ", orderByStart);
			if (orderByEnd == -1) {
				orderByEnd = sql.length();
			}
		}
		String orderByContent = sql.substring(orderByStart, orderByEnd);
		String[] orderByNames = orderByContent.split("\\,");
		for (int i=0; i<orderByNames.length; i++) {
			if (orderByNames[i].trim().length() > 0) {
				if (orderByNames[i].trim().toLowerCase().endsWith("desc")) {
					orderByNames[i] += " NULLS LAST";
				} else {
					orderByNames[i] += " NULLS FIRST";
				}
			}
		}
		orderByContent = StringUtils.join(orderByNames, ",");
		sql = sql.substring(0, orderByStart) + orderByContent + sql.substring(orderByEnd); 
		return super.onPrepareStatement(sql);
	}
	
}