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/*  Copyright 1999 Vince Via [email protected]
    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 com.viaoa.object;

import com.viaoa.datasource.OASelect;
import com.viaoa.sync.OASync;
import com.viaoa.sync.OASyncClient;
import com.viaoa.sync.OASyncDelegate;
import com.viaoa.sync.remote.RemoteServerInterface;
import com.viaoa.util.OAString;

/**
 * Used to find a object with a unique value, with the option to create one that 
 * is concurrently safe (done on server).
 * @author vvia
 */
public class OAObjectUniqueDelegate {

    private static final Object Lock = new Object();

    /**
     * Find and/or create unique OAObject.
     */
    public static OAObject getUnique(final Class clazz, final String propertyName, final Object uniqueKey, final boolean bAutoCreate) {
        
        if (clazz == null) return null;
        if (uniqueKey == null) return null;
        if (OAString.isEmpty(propertyName)) return null;
        
        OAObject oaObj = (OAObject) OAObjectCacheDelegate.find(clazz, propertyName, uniqueKey);
        if (oaObj != null) return oaObj;
        
        // not found
        if (OASyncDelegate.isClient(clazz)) {
            OASyncClient sc = OASync.getSyncClient();
            RemoteServerInterface rs;
            try {
                rs = sc.getRemoteServer();

                if (rs != null) {
                    oaObj = rs.getUnique(clazz, propertyName, uniqueKey, bAutoCreate);
                    return oaObj;
                }
            }
            catch (Exception e) {
                throw new RuntimeException("getUnique() getRemoteServer() exception", e);
            }
        }
        
        OASelect select = new OASelect(clazz);
        select.setWhere(propertyName+" = ?", new Object[] {uniqueKey});
        oaObj = select.next();
        if (oaObj != null) {
            return oaObj;
        }
        if (!bAutoCreate) return null;

        // need to create new, this needs to be synchronized
        synchronized (Lock) {
            oaObj = getUnique(clazz, propertyName, uniqueKey, false);
            if (oaObj != null) return oaObj;
            oaObj = (OAObject) OAObjectReflectDelegate.createNewObject(clazz);
            try {
                OAThreadLocalDelegate.setLoading(true);
                oaObj.setProperty(propertyName, uniqueKey);
            }
            finally {
                OAThreadLocalDelegate.setLoading(false);
            }
        }
        
        return oaObj;
    }
    
    
    
}