/**
 * SQL-DK
 * Copyright © 2013 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;

import info.globalcode.sql.dk.batch.Batch;
import info.globalcode.sql.dk.configuration.DatabaseDefinition;
import info.globalcode.sql.dk.formatting.ColumnsHeader;
import info.globalcode.sql.dk.formatting.Formatter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.SQLWarning;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author Ing. František Kučera (frantovo.cz)
 */
public class DatabaseConnection implements AutoCloseable {

	private static final Logger log = Logger.getLogger(DatabaseConnection.class.getName());
	private DatabaseDefinition databaseDefinition;
	private Connection connection;

	public DatabaseConnection(DatabaseDefinition databaseDefinition) throws SQLException {
		this.databaseDefinition = databaseDefinition;

		connection = DriverManager.getConnection(databaseDefinition.getUrl(), databaseDefinition.getUserName(), databaseDefinition.getPassword());
	}

	public void executeQuery(SQLCommand sqlCommand, Formatter formatter) throws SQLException {
		formatter.writeStartBatch();
		formatter.writeStartDatabase(databaseDefinition);
		processCommand(sqlCommand, formatter);
		formatter.writeEndDatabase();
		formatter.writeEndBatch();
	}

	public void executeBatch(Batch batch, Formatter formatter) throws SQLException {
		formatter.writeStartBatch();
		formatter.writeStartDatabase(databaseDefinition);
		while (batch.hasNext()) {
			processCommand(batch.next(), formatter);
		}
		formatter.writeEndDatabase();
		formatter.writeEndBatch();
	}

	private void processCommand(SQLCommand sqlCommand, Formatter formatter) throws SQLException {
		try (PreparedStatement ps = sqlCommand.prepareStatement(connection)) {
			log.log(Level.FINE, "Statement prepared");
			sqlCommand.parametrize(ps);

			boolean isRS = ps.execute();
			log.log(Level.FINE, "Statement executed");
			if (isRS) {
				try (ResultSet rs = ps.getResultSet()) {
					processResultSet(sqlCommand, rs, formatter);
				}
			} else {
				processUpdateResult(sqlCommand, ps, formatter);
			}
			logWarnings(ps);

			while (ps.getMoreResults() || ps.getUpdateCount() > -1) {
				ResultSet rs = ps.getResultSet();
				if (rs == null) {
					processUpdateResult(sqlCommand, ps, formatter);
				} else {
					processResultSet(sqlCommand, rs, formatter);
					rs.close();
				}
				logWarnings(ps);
			}
		}
	}

	private void processUpdateResult(SQLCommand sqlCommand, PreparedStatement ps, Formatter formatter) throws SQLException {
		formatter.writeStartUpdatesResult();
		formatter.writeQuery(sqlCommand.getQuery());
		formatter.writeParameters(sqlCommand.getParameters());
		formatter.writeUpdatedRowsCount(ps.getUpdateCount());
		formatter.writeEndUpdatesResult();
	}

	private void processResultSet(SQLCommand sqlCommand, ResultSet rs, Formatter formatter) throws SQLException {
		formatter.writeStartResultSet();
		formatter.writeQuery(sqlCommand.getQuery());
		formatter.writeParameters(sqlCommand.getParameters());

		processResultSetRows(rs, formatter);

		formatter.writeEndResultSet();
	}

	private void processResultSetRows(ResultSet rs, Formatter formatter) throws SQLException {
		formatter.writeColumnsHeader(new ColumnsHeader(rs.getMetaData()));
		int columnCount = rs.getMetaData().getColumnCount();

		while (rs.next()) {
			formatter.writeStartRow();

			for (int i = 1; i <= columnCount; i++) {
				formatter.writeColumnValue(rs.getObject(i));
			}

			formatter.writeEndRow();
		}

	}

	private void logWarnings(PreparedStatement ps) throws SQLException {
		SQLWarning w = ps.getWarnings();
		while (w != null) {
			log.log(Level.WARNING, "SQL: {0}", w.getLocalizedMessage());
			w = w.getNextWarning();
		}
		ps.clearWarnings();
	}

	/**
	 * Tests if this connection is live.
	 *
	 * @return true if test was successful
	 * @throws SQLException if test fails
	 */
	public boolean test() throws SQLException {
		connection.getAutoCommit();
		return true;
	}

	@Override
	public void close() throws SQLException {
		connection.close();
	}
}