package de.intevation.db;

import de.intevation.utils.XML;

import java.util.HashMap;

import org.w3c.dom.Document;

import javax.xml.xpath.XPathConstants;

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

import org.apache.log4j.Logger;

public class ConnectionBuilder
{
    private static Logger log = Logger.getLogger(ConnectionBuilder.class);

    public static final String XPATH_DRIVER   = "/sync/side[@name=$type]/db/driver/text()";
    public static final String XPATH_USER     = "/sync/side[@name=$type]/db/user/text()";
    public static final String XPATH_PASSWORD = "/sync/side[@name=$type]/db/password/text()";
    public static final String XPATH_URL      = "/sync/side[@name=$type]/db/url/text()";

    protected String type;
    protected String driver;
    protected String user;
    protected String password;
    protected String url;

    public ConnectionBuilder(String type, Document document) {
        this.type = type;
        extractCredentials(document);
    }

    protected void extractCredentials(Document document) {
        HashMap<String, String> map = new HashMap<String, String>();
        map.put("type", type);

        driver = (String)XML.xpath(
            document, XPATH_DRIVER, XPathConstants.STRING, null, map);
        user = (String)XML.xpath(
            document, XPATH_USER, XPathConstants.STRING, null, map);
        password = (String)XML.xpath(
            document, XPATH_PASSWORD, XPathConstants.STRING, null, map);
        url = (String)XML.xpath(
            document, XPATH_URL, XPathConstants.STRING, null, map);

        if (log.isDebugEnabled()) {
            log.debug("driver: " + driver);
            log.debug("user: " + user);
            log.debug("password: *******");
            log.debug("url: " + url);
        }
    }

    public Connection getConnection() throws SQLException {

        if (driver != null && driver.length() > 0) {
            try {
                Class.forName(driver);
            }
            catch (ClassNotFoundException cnfe) {
                throw new SQLException(cnfe);
            }
        }

        Connection connection =
            DriverManager.getConnection(url, user, password);

        connection.setAutoCommit(false);

        DatabaseMetaData metaData = connection.getMetaData();

        if (metaData.supportsTransactionIsolationLevel(
            Connection.TRANSACTION_READ_UNCOMMITTED)) {
            connection.setTransactionIsolation(
                Connection.TRANSACTION_READ_UNCOMMITTED);
        }

        return connection;
    }

    public ConnectedStatements getConnectedStatements() throws SQLException {
        return new ConnectedStatements(
            getConnection(),
            new Statements(type, driver != null ? driver : "")
                .getStatements());
    }
}
// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :