/*
 * Copyright (c) 2017, Tony Opara
 *        All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 * - Redistributions of source code must retain the above copyright notice, this 
 *   list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice, 
 *   this list of conditions and the following disclaimer in the documentation 
 *   and/or other materials provided with the distribution.
 * 
 * Neither the name of Google nor the names of its contributors may be used to 
 * endorse or promote products derived from this software without specific 
 * prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR 
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.google.refine.extension.database.pgsql;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.refine.extension.database.DatabaseConfiguration;
import com.google.refine.extension.database.DatabaseServiceException;
import com.google.refine.extension.database.SQLType;

public class PgSQLConnectionManager {

    private static final Logger logger = LoggerFactory.getLogger("PgSQLConnectionManager");
    private Connection connection;
    private SQLType type;

    private static PgSQLConnectionManager instance;

    /**
     * 
     * @param type
     * @param databaseConfiguration
     * @throws SQLException
     */
    private PgSQLConnectionManager() {
        type = SQLType.forName(PgSQLDatabaseService.DB_NAME);

    }

    /**
     * Create a new instance of this connection manager.
     *
     * @return an instance of the manager
     *
     * @throws DatabaseServiceException
     */
    public static PgSQLConnectionManager getInstance() throws DatabaseServiceException {
        if (instance == null) {
            if (logger.isDebugEnabled()) {
                logger.debug("::Creating new PgSQL ConnectionManager ::");
            }

            instance = new PgSQLConnectionManager();

        }
        return instance;
    }

    /**
     * Get the SQL Database type.
     *
     * @return the type
     */
    public SQLType getType() {
        return this.type;
    }

    /**
     * testConnection
     * 
     * @param databaseConfiguration
     * @return
     */
    public boolean testConnection(DatabaseConfiguration databaseConfiguration) throws DatabaseServiceException {

        try {
            boolean connResult = false;

            Connection conn = getConnection(databaseConfiguration, true);
            if (conn != null) {
                connResult = true;
                conn.close();
            }

            return connResult;

        } catch (SQLException e) {
            logger.error("Test connection Failed!", e);
            throw new DatabaseServiceException(e);
        }

    }

    /**
     * Get a connection form the connection pool.
     *
     * @return connection from the pool
     */
    public Connection getConnection(DatabaseConfiguration databaseConfiguration, boolean forceNewConnection)
            throws DatabaseServiceException {
        try {

            // logger.info("connection::{}, forceNewConnection: {}", connection, forceNewConnection);

            if (connection != null && !forceNewConnection) {
                // logger.info("connection closed::{}", connection.isClosed());
                if (!connection.isClosed()) {
                    if (logger.isDebugEnabled()) {
                        logger.debug("Returning existing connection::{}", connection);
                    }
                    return connection;
                }
            }

            Class.forName(type.getClassPath());
            DriverManager.setLoginTimeout(10);
            String dbURL = databaseConfiguration.toURI().toString();
            connection = DriverManager.getConnection(dbURL, databaseConfiguration.getDatabaseUser(),
                    databaseConfiguration.getDatabasePassword());

            logger.debug("*** Acquired New  connection for ::{} **** ", dbURL);

            return connection;

        } catch (ClassNotFoundException e) {
            logger.error("Jdbc Driver not found", e);
            throw new DatabaseServiceException(e.getMessage());
        } catch (SQLException e) {
            logger.error("SQLException::Couldn't get a Connection!", e);
            throw new DatabaseServiceException(e);
        }
    }

    public void shutdown() {

        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                logger.warn("Non-Managed connection could not be closed. Whoops!", e);
            }
        }

    }

}
