/**

  * SQL-DK

  * Copyright © 2014 František Kučera (frantovo.cz)

  *

  * This program is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, either version 3 of the License, or

  * (at your option) any later version.

  *

  * 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 General Public License for more details.

  *

  * You should have received a copy of the GNU General Public License

  * along with this program. If not, see <http://www.gnu.org/licenses/>.

  */

 package info.globalcode.sql.dk.batch;

 import info.globalcode.sql.dk.Parameter;

 import info.globalcode.sql.dk.SQLCommand;

 import info.globalcode.sql.dk.SQLCommandNamed;

 import java.io.DataOutputStream;

 import java.io.IOException;

 import java.io.OutputStream;

 import static info.globalcode.sql.dk.batch.BatchConstants.*;

 import java.io.ByteArrayOutputStream;

 import java.sql.SQLException;

 import java.util.List;

 /**

  *

  * @author Ing. František Kučera (frantovo.cz)

  */

 public class BatchEncoder {

 	public int encode(SQLCommand sqlCommand, OutputStream out) throws BatchException {

 		try {

 			ByteArrayOutputStream bufferAOS = new ByteArrayOutputStream();

 			DataOutputStream buffer = new DataOutputStream(bufferAOS);

 			buffer.write(BATCH_HEADER);

 			if (sqlCommand instanceof SQLCommandNamed) {

 				sqlCommand = ((SQLCommandNamed) sqlCommand).getSQLCommandNumbered();

 			}

 			writeNextString(sqlCommand.getQuery(), buffer);

 			List<? extends Parameter> parameters = sqlCommand.getParameters();

 			buffer.writeInt(parameters.size());

 			for (Parameter p : parameters) {

 				buffer.writeInt(p.getType().getCode());

 				writeNextString((String) p.getValue(), buffer); // parameters are encoded before any preprocessing

 			}

 			buffer.flush();

 			bufferAOS.writeTo(out);

 			out.flush();

 			return bufferAOS.size();

 		} catch (IOException e) {

 			throw new BatchException("Unable to write SQL command: " + sqlCommand, e);

 		} catch (SQLException e) {

 			throw new BatchException("Unable to converd named SQL command to numbered: " + sqlCommand, e);

 		}

 	}

 	private void writeNextString(String s, DataOutputStream out) throws IOException {

 		byte[] bytes = toBytes(s);

 		out.writeInt(bytes.length);

 		out.write(bytes);

 	}

 	private static byte[] toBytes(String s) {

 		if (s == null) {

 			return new byte[]{};

 		} else {

 			return s.getBytes(CHARSET);

 		}

 	}

 }