/* ======================================================================
The Bodington System Software License, Version 1.0
 
Copyright (c) 2001 The University of Leeds.  All rights reserved.
 
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
 
1.  Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
 
2.  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.
 
3.  The end-user documentation included with the redistribution, if any,
must include the following acknowledgement:  "This product includes
software developed by the University of Leeds
(http://www.bodington.org/)."  Alternately, this acknowledgement may
appear in the software itself, if and wherever such third-party
acknowledgements normally appear.
 
4.  The names "Bodington", "Nathan Bodington", "Bodington System",
"Bodington Open Source Project", and "The University of Leeds" must not be
used to endorse or promote products derived from this software without
prior written permission. For written permission, please contact
d.gardner@leeds.ac.uk.
 
5.  The name "Bodington" may not appear in the name of products derived
from this software without prior written permission of the University of
Leeds.
 
THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO,  TITLE,  THE IMPLIED WARRANTIES
OF QUALITY  AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
EVENT SHALL THE UNIVERSITY OF LEEDS OR ITS 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.
=========================================================
 
This software was originally created by the University of Leeds and may contain voluntary
contributions from others.  For more information on the Bodington Open Source Project, please
see http://bodington.org/
 
====================================================================== */

package org.bodington.database;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Enumeration;
import java.util.Properties;

import org.apache.commons.dbcp.BasicDataSource;

/**
 * Wraps up the commons-dbcp for use in Bodington. This class attempts to set
 * the configuration of the commons-dbcp through reflection so that all the 
 * properties supported by commons-dbcp are supported here. All properties should
 * be prefixed with <code>sqldatabase.dbcp</code>.
 * <p>
 * 
 * Example configuration:<br>
 * <pre>
 * sqldatabase.dbcp.url=jdbc:postgres://localhost/weblearn
 * sqldatabase.dbcp.username=myusername
 * sqldatabase.dbcp.password=mypassword
 * sqldatabase.dbcp.driverClassName=org.postgresql.Driver
 * </pre>
 * 
 * @author buckett
 */
public class CommonsConnectionPool implements ConnectionPool
{
    
    private final static String PROPERTIES_PREFIX = "sqldatabase.dbcp.";
    
    BasicDataSource dataSource;

    /**
     * Create a connection pool using the commons-dbcp library.
     * @throws ConnectionPoolException If we unable to find the commons-dbcp classes.
     */
    public CommonsConnectionPool( Properties bodingtonProperties ) throws ConnectionPoolException
    {
      
        try
        {
            Class.forName("org.apache.commons.dbcp.BasicDataSource");
        }
        catch (ClassNotFoundException cnfe)
        {
            throw new ConnectionPoolException("Unable to find the commons dbcp classes.");
        }
        
        dataSource =  new BasicDataSource();
        
        Properties properties = beginingWith(bodingtonProperties, PROPERTIES_PREFIX);
        Enumeration keys = properties.keys();
            
        while (keys.hasMoreElements())
        {
            final String key = (String)keys.nextElement();
            final String value = (String)properties.getProperty(key);
            
            // Not interested in empty values.
            if (value == null || value.length() < 1)
                continue;
            
            try
            {
                // Rather than throwing exceptions we should return null from
                // the various getNumber/getBoolean routines
                Long longValue = new Long(0);
                try
                {
                   longValue = getNumber(value);
                    callMethod(key, Long.TYPE, longValue);
                    continue;
                }
                catch (NoSuchMethodException nsme)
                {
                    callMethod(key, Integer.TYPE, new Integer(longValue.intValue()));
                    continue;
                }
                catch (IllegalArgumentException iae)
                {}
                try
                {
                    final Boolean booleanValue = getBoolean(value);
                    callMethod(key, Boolean.TYPE, booleanValue);
                    continue;
                }
                catch (IllegalArgumentException iae)
                {}
                callMethod(key, String.class, value);
            }
            catch (Exception e)
            {}
        }
    }

    /**
     * Gets a connection object.
     * @throws ConnectionPoolException If there we are unable to get a connection. 
     */
    public Connection getConnection(Object user) throws ConnectionPoolException
    {
        try
        {
            return dataSource.getConnection();
        }
        catch (SQLException sqle)
        {
            throw new ConnectionPoolException(sqle.getMessage());
        }
    }

    /**
     * Returns the connection to the pool.
     */
    public void freeConnection(Connection free_con)
        throws ConnectionPoolException
    {
        try
        {
            free_con.close();
        }
        catch (SQLException sqle)
        {}
    }

    /**
     * Gets only the properties that begin with the selected prefix.
     * The returned properties object keys don't have the prefix any more.
     * @param allProperties The properties to look through.
     * @param prefix The prefix to look for.
     * @return A new properties object containing onlye those that started with the prefix.
     */
    private static Properties beginingWith(Properties allProperties, String prefix)
    {
        Properties selectedProperties = new Properties();
        Enumeration keys = allProperties.keys();
        while (keys.hasMoreElements())
        {
            final String key = (String)keys.nextElement();
            if (key.startsWith(prefix))
            {
                selectedProperties.put(key.substring(prefix.length()), allProperties.get(key));
            }
            
        }
        return selectedProperties;
    }
    
    private static Long getNumber(String value)
    {
        try 
        {
           return new Long(Long.parseLong(value)); 
        }
        catch (NumberFormatException nfe)
        {
          throw new IllegalArgumentException();  
        }
    }
    
    private static Boolean getBoolean(String value)
    {
        if (value.equalsIgnoreCase("true"))
            return Boolean.valueOf(true);
        if (value.equalsIgnoreCase("false"))
            return Boolean.valueOf(false);
        throw new IllegalArgumentException();
    }
    
    private static String getMethodForProperty(String property)
    {
        return "set"+ Character.toUpperCase(property.charAt(0))+ property.substring(1);
    }
    
    private void callMethod(String property, Class clazz, Object value) throws IllegalArgumentException, SecurityException, IllegalAccessException, InvocationTargetException, NoSuchMethodException
    {
        BasicDataSource.class.getMethod(getMethodForProperty(property),
            new Class[]{clazz}).invoke(dataSource, new Object[]{value});
    }
    
    /**
     * Method to allow unit testing of the configuration.
     * @return The internal DataSource object.
     */
    BasicDataSource getBasicDataSource()
    {
        return dataSource;
    }
}