/**

 * 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

 *

 * 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);

		}

	}

}