package com.tesora.dve.queryplan;

/*
 * #%L
 * Tesora Inc.
 * Database Virtualization Engine
 * %%
 * Copyright (C) 2011 - 2014 Tesora Inc.
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 * 
 * This program 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 Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 * #L%
 */

import java.sql.Types;

import com.tesora.dve.db.DBResultConsumer;
import com.tesora.dve.exceptions.PEException;
import com.tesora.dve.resultset.ColumnSet;
import com.tesora.dve.resultset.ResultRow;
import com.tesora.dve.variables.VariableHandler;
import com.tesora.dve.worker.WorkerGroup;


public class QueryStepGetSessionVariableOperation extends QueryStepOperation {
	
	@SuppressWarnings("rawtypes")
	VariableHandler handler;
	private String alias;

	public QueryStepGetSessionVariableOperation(VariableHandler<?> handler, String alias) throws PEException {
		super(nullStorageGroup);
		this.handler = handler;
		this.alias = alias;
	}
	
	public QueryStepGetSessionVariableOperation(VariableHandler<?> handler) throws PEException {
		this(handler, handler.getName());
	}

	@SuppressWarnings("unchecked")
	@Override
	public void executeSelf(ExecutionState estate, WorkerGroup wg, DBResultConsumer resultConsumer)
			throws Throwable {
		resultConsumer.inject(ColumnSet.singleColumn(alias, Types.VARCHAR),
				ResultRow.singleRow(handler.toRow(handler.getSessionValue(estate.getConnection()))));
	}

	@Override
	public boolean requiresWorkers() {
		return false;
	}
	
}