/*
    * Copyright 2006 Outsource Cafe, Inc.
    *
    * Licensed under the Apache License, Version 2.0 (the 'License')
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *    http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an 'AS IS' BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.javagen.agile.db.util;
  
  import java.io.PrintWriter;
  import java.sql.Connection;
  import java.sql.DriverManager;
  import java.sql.SQLException;
  import java.util.Properties;
  
  import javax.sql.DataSource;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  /***
   * A generic way to access database drivers given the driver class name, url, username and password.
   * <p>
   * Compiled from code found in the Spring Framework.
   *
   * @author Richard Easterling
   */
  public class DriverManagerDataSource implements DataSource {
  
  	private static final Log log = LogFactory.getLog(DriverManagerDataSource.class);
  
  	private String driverClassName;
  
  	private String url;
  
  	private String username;
  
  	private String password;
  
  	private Properties connectionProperties;
  
  
  	/***
  	 * Constructor for bean-style configuration.
  	 */
  	public DriverManagerDataSource() {
  	}
  
  	/***
  	 * Create a new DriverManagerDataSource with the given standard
  	 * DriverManager parameters.
  	 * @param driverClassName the JDBC driver class name
  	 * @param url the JDBC URL to use for accessing the DriverManager
  	 * @param username the JDBC username to use for accessing the DriverManager
  	 * @param password the JDBC password to use for accessing the DriverManager
  	 * @see java.sql.DriverManager#getConnection(String, String, String)
  	 */
  	public DriverManagerDataSource(String driverClassName, String url, String username, String password)
  			throws SQLException {
  		setDriverClassName(driverClassName);
  		setUrl(url);
  		setUsername(username);
  		setPassword(password);
  	}
  
  	/***
  	 * Create a new DriverManagerDataSource with the given standard
  	 * DriverManager parameters.
  	 * @param url the JDBC URL to use for accessing the DriverManager
  	 * @param username the JDBC username to use for accessing the DriverManager
  	 * @param password the JDBC password to use for accessing the DriverManager
  	 * @see java.sql.DriverManager#getConnection(String, String, String)
  	 */
  	public DriverManagerDataSource(String url, String username, String password)
  			throws SQLException {
  		setUrl(url);
  		setUsername(username);
  		setPassword(password);
  	}
  
  	/***
  	 * Create a new DriverManagerDataSource with the given JDBC URL,
  	 * not specifying a username or password for JDBC access.
  	 * @param url the JDBC URL to use for accessing the DriverManager
  	 * @see java.sql.DriverManager#getConnection(String)
  	 */
  	public DriverManagerDataSource(String url)
  			throws SQLException {
  		setUrl(url);
  	}
  
 
 	/***
 	 * Set the JDBC driver class name. This driver will get initialized
 	 * on startup, registering itself with the JDK's DriverManager.
 	 * <p>Alternatively, consider initializing the JDBC driver yourself
 	 * before instantiating this DataSource.
 	 * @see Class#forName(String)
 	 * @see java.sql.DriverManager#registerDriver(java.sql.Driver)
 	 */
 	public void setDriverClassName(String driverClassName) throws SQLException {
 		if (driverClassName==null || driverClassName.trim().length()==0) {
 			throw new IllegalArgumentException("driverClassName must not be empty");
 		}
 		this.driverClassName = driverClassName;
 		try {
 			Class.forName(this.driverClassName, true, getDefaultClassLoader());
 		}
 		catch (ClassNotFoundException e) {
 			SQLException ex = new SQLException("Could not load JDBC driver class [" + this.driverClassName + "]: "+e.getMessage());
 			ex.initCause(e);
 			throw ex;
 		}
 		if (log.isInfoEnabled()) {
 			log.info("Loaded JDBC driver: " + this.driverClassName);
 		}
 	}
 
 	/***
 	 * Return the JDBC driver class name, if any.
 	 */
 	public String getDriverClassName() {
 		return driverClassName;
 	}
 
 	/***
 	 * Set the JDBC URL to use for accessing the DriverManager.
 	 * @see java.sql.DriverManager#getConnection(String, String, String)
 	 */
 	public void setUrl(String url) {
 		if (url==null || url.trim().length()==0) {
 			throw new IllegalArgumentException("url must not be empty");
 		}
 		this.url = url;
 	}
 
 	/***
 	 * Return the JDBC URL to use for accessing the DriverManager.
 	 */
 	public String getUrl() {
 		return url;
 	}
 
 	/***
 	 * Set the JDBC username to use for accessing the DriverManager.
 	 * @see java.sql.DriverManager#getConnection(String, String, String)
 	 */
 	public void setUsername(String username) {
 		this.username = username;
 	}
 
 	/***
 	 * Return the JDBC username to use for accessing the DriverManager.
 	 */
 	public String getUsername() {
 		return username;
 	}
 
 	/***
 	 * Set the JDBC password to use for accessing the DriverManager.
 	 * @see java.sql.DriverManager#getConnection(String, String, String)
 	 */
 	public void setPassword(String password) {
 		this.password = password;
 	}
 
 	/***
 	 * Return the JDBC password to use for accessing the DriverManager.
 	 */
 	public String getPassword() {
 		return password;
 	}
 
 	/***
 	 * Specify arbitrary connection properties as key/value pairs,
 	 * to be passed to the DriverManager.
 	 * <p>Can also contain "user" and "password" properties. However,
 	 * any "username" and "password" bean properties specified on this
 	 * DataSource will override the respective connection properties.
 	 * @see java.sql.DriverManager#getConnection(String, java.util.Properties)
 	 */
 	public void setConnectionProperties(Properties connectionProperties) {
 		this.connectionProperties = connectionProperties;
 	}
 
 	/***
 	 * Return the connection properties to be passed to the DriverManager,
 	 * if any.
 	 */
 	public Properties getConnectionProperties() {
 		return connectionProperties;
 	}
 
 
 	/***
 	 * This implementation delegates to <code>getConnectionFromDriverManager</code>,
 	 * using the default username and password of this DataSource.
 	 * @see #getConnectionFromDriverManager()
 	 */
 	public Connection getConnection() throws SQLException {
 		return getConnectionFromDriverManager();
 	}
 
 	/***
 	 * This implementation delegates to <code>getConnectionFromDriverManager</code>,
 	 * using the given username and password.
 	 * @see #getConnectionFromDriverManager(String, String)
 	 */
 	public Connection getConnection(String username, String password) throws SQLException {
 		return getConnectionFromDriverManager(username, password);
 	}
 
 	/***
 	 * Get a Connection from the DriverManager,
 	 * using the default username and password of this DataSource.
 	 * @see #getConnectionFromDriverManager(String, String)
 	 */
 	protected Connection getConnectionFromDriverManager() throws SQLException {
 		return getConnectionFromDriverManager(getUsername(), getPassword());
 	}
 
 	/***
 	 * Build properties for the DriverManager, including the given username
 	 * and password (if any).
 	 * @see #getConnectionFromDriverManager(String, java.util.Properties)
 	 */
 	protected Connection getConnectionFromDriverManager(String username, String password)
 	    throws SQLException {
 
 		Properties props = new Properties(getConnectionProperties());
 		if (username != null) {
 			props.setProperty("user", username);
 		}
 		if (password != null) {
 			props.setProperty("password", password);
 		}
 		return getConnectionFromDriverManager(getUrl(), props);
 	}
 
 	/***
 	 * Getting a connection using the nasty static from DriverManager is extracted
 	 * into a protected method to allow for easy unit testing.
 	 * @see java.sql.DriverManager#getConnection(String, java.util.Properties)
 	 */
 	protected Connection getConnectionFromDriverManager(String url, Properties props)
 	    throws SQLException {
 
 		if (log.isDebugEnabled()) {
 			log.debug("Creating new JDBC Connection to [" + url + "]");
 		}
 		return DriverManager.getConnection(url, props);
 	}
 
 	/***
 	 * Returns 0: means use default system timeout.
 	 */
 	public int getLoginTimeout() throws SQLException {
 		return 0;
 	}
 
 	public void setLoginTimeout(int timeout) throws SQLException {
 		throw new UnsupportedOperationException("setLoginTimeout");
 	}
 
 	/***
 	 * LogWriter methods are unsupported.
 	 */
 	public PrintWriter getLogWriter() {
 		throw new UnsupportedOperationException("getLogWriter");
 	}
 
 	/***
 	 * LogWriter methods are unsupported.
 	 */
 	public void setLogWriter(PrintWriter pw) throws SQLException {
 		throw new UnsupportedOperationException("setLogWriter");
 	}
 
     public static ClassLoader getDefaultClassLoader() {
         ClassLoader cl = Thread.currentThread().getContextClassLoader();
         if (cl == null) {
             // No thread context class loader -> use class loader of this class.
             cl = DriverManagerDataSource.class.getClassLoader();
         }
         return cl;
     }
 }