package connection;

import exceptions.DAOException;
import exceptions.JDBCConnectionException;
import logger.Logger;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.ResourceBundle;

public class ConnectionPool {
    private List<Connection> connections;
    private List<Connection> usedConnections;

    /**
     * init connection pool
     * @throws JDBCConnectionException
     */
    public ConnectionPool() throws JDBCConnectionException {
        connections = Collections.synchronizedList(new ArrayList<Connection>());
        usedConnections = Collections.synchronizedList(new ArrayList<Connection>());
    }

    /**
     * get connection
     * @throws JDBCConnectionException
     */
    public Connection getConnection() throws JDBCConnectionException {
        Connection conn = null;
        if(connections.size() < 1) {
            ResourceBundle resource = ResourceBundle.getBundle("properties/database");
            String url = resource.getString("url");
            String driver = resource.getString("driver");
            String user = resource.getString("user");
            String pass = "";
            try {
                Class.forName(driver).newInstance();
                conn = DriverManager.getConnection(url, user, pass);
            } catch (ClassNotFoundException e) {
                throw new JDBCConnectionException ("Driver is not loaded!");
            } catch (InstantiationException | IllegalAccessException | SQLException e) {
                Logger.logError(Logger.connectorLogger, e);
            }
            usedConnections.add(conn);
        } else {
            conn = connections.get(connections.size() - 1);
            connections.remove(connections.size() - 1);
            usedConnections.add(conn);
        }
        return conn;
    }

    /**
     * release connection
     * @throws JDBCConnectionException
     */
    public void releaseConnection() throws JDBCConnectionException {
        Connection conn = usedConnections.get(usedConnections.size() - 1);
        usedConnections.remove(usedConnections.size() - 1);
        connections.add(conn);

    }

    /**
     * close func
     * @throws JDBCConnectionException
     */
    public void close(Connection conn) throws JDBCConnectionException {
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                throw new JDBCConnectionException("Can't close connection");
            }
        }
    }
}