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/**
 * Copyright (C) 2009 Authors
 * 
 * This file is part of Ebean.
 * 
 * Ebean 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.
 *  
 * Ebean 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 Ebean; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA  
 */
package com.avaje.ebeaninternal.server.query;

import java.util.List;

import com.avaje.ebean.OrderBy;
import com.avaje.ebean.OrderBy.Property;
import com.avaje.ebeaninternal.api.SpiQuery;
import com.avaje.ebeaninternal.server.deploy.BeanDescriptor;
import com.avaje.ebeaninternal.server.deploy.BeanProperty;
import com.avaje.ebeaninternal.server.deploy.BeanPropertyAssoc;
import com.avaje.ebeaninternal.server.deploy.id.IdBinder;
import com.avaje.ebeaninternal.server.el.ElPropertyValue;

/**
 * Creates the order by expression clause.
 */
public class CQueryOrderBy {

    private final BeanDescriptor desc;
    
    private final SpiQuery query;
    
    /**
     * Create the logical order by clause.
     */
    public static String parse(BeanDescriptor desc, SpiQuery query) {
        return new CQueryOrderBy(desc, query).parseInternal();
    }
    
    private CQueryOrderBy(BeanDescriptor desc, SpiQuery query) {
        this.desc = desc;
        this.query = query;
    }
    
    private String parseInternal() {
        
        OrderBy orderBy = query.getOrderBy();
        if (orderBy == null){
            return null;
        }
        
        StringBuilder sb = new StringBuilder();

        List properties = orderBy.getProperties();
        if (properties.isEmpty()){
            // order by clause removed by filterMany()
            return null;
        }
        for (int i = 0; i < properties.size(); i++) {
            if (i > 0){
                sb.append(", ");
            }
            Property p = properties.get(i);
            String expression = parseProperty(p);
            sb.append(expression);
        }
        return sb.toString();
    }
    
    private String parseProperty(Property p) {
        
        String propName = p.getProperty();
        ElPropertyValue el  = desc.getElGetValue(propName);
        if (el == null){
            return p.toStringFormat();
        } 
        
        BeanProperty beanProperty = el.getBeanProperty();
        if (beanProperty instanceof BeanPropertyAssoc){
            BeanPropertyAssoc ap = (BeanPropertyAssoc)beanProperty;
            IdBinder idBinder = ap.getTargetDescriptor().getIdBinder();
            return idBinder.getOrderBy(el.getElName(), p.isAscending());
        }
        
        return p.toStringFormat();
    }
}