package de.intevation.flys.artifacts.datacage;

import de.intevation.artifacts.common.utils.Config;

import java.sql.SQLException;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSource;

import org.apache.log4j.Logger;

public class DBConnection
{ 
    private static Logger logger = Logger.getLogger(DBConnection.class);

     /**
     * XPath to access the database driver within the global configuration.
     */
    public static final String DB_DRIVER =
        "/artifact-database/datacage/driver/text()";
    /**
     * XPath to access the database URL within the global configuration.
     */
    public static final String DB_URL =
        "/artifact-database/datacage/url/text()";
    /**
     * XPath to access the database use within the global configuration.
     */
    public static final String DB_USER =
        "/artifact-database/datacage/user/text()";
    /**
     * XPath to access the database password within the global configuration.
     */
    public static final String DB_PASSWORD =
        "/artifact-database/datacage/password/text()";

    /**
     * The default database driver: H2
     */
    public static final String DEFAULT_DRIVER =
        "org.h2.Driver";

    /**
     * The default database user: ""
     */
    public static final String DEFAULT_USER = "";

    /**
     * The default database password: ""
     */
    public static final String DEFAULT_PASSWORD = "";


    public static final String DEFAULT_URL =
        "jdbc:h2:mem;INIT=RUNSCRIPT FROM '${artifacts.config.dir}/datacage.sql'";

    private static BasicDataSource dataSource;

    private DBConnection() {
    }

    private static final void addShutdownHook() {
        Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                if (dataSource != null) {
                    try {
                        dataSource.close();
                    }
                    catch (SQLException sqle) {
                    }
                    dataSource = null;
                }
            }
        });

    }

    public static synchronized DataSource getDataSource() {
        if (dataSource == null) {
            dataSource = new BasicDataSource();

            String driver = Config.getStringXPath(
                DB_DRIVER, DEFAULT_DRIVER);

            String url = Config.getStringXPath(
                DB_URL, DEFAULT_URL);

            url = Config.replaceConfigDir(url);

            String user = Config.getStringXPath(
                DB_USER, DEFAULT_USER);

            String password = Config.getStringXPath(
                DB_PASSWORD, DEFAULT_PASSWORD);

            logger.info("database driver: " + driver);
            logger.info("database url: " + url);

            dataSource.setDriverClassName(driver);
            dataSource.setUsername(user);
            dataSource.setPassword(password);
            dataSource.setUrl(url);
            addShutdownHook();
        }

        return dataSource;
    }
}
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