<?php
/**
 * @version		$Id: table.php 20196 2011-01-09 02:40:25Z ian $
 * @package		Joomla.Framework
 * @subpackage	Table
 * @copyright	Copyright (C) 2005 - 2011 Open Source Matters, Inc. All rights reserved.
 * @license		GNU General Public License version 2 or later; see LICENSE.txt
 */

defined('JPATH_BASE') or die;

/**
 * Abstract Table class
 *
 * Parent class to all tables.
 *
 * @package		Joomla.Framework
 * @subpackage	Table
 * @since		1.0
 * @tutorial	Joomla.Framework/jtable.cls
 * @link		http://docs.joomla.org/JTable
 */
abstract class JTable extends JObject
{
	/**
	 * Name of the database table to model.
	 *
	 * @var		string
	 * @since	1.0
	 */
	protected $_tbl	= '';

	/**
	 * Name of the primary key field in the table.
	 *
	 * @var		string
	 * @since	1.0
	 */
	protected $_tbl_key = '';

	/**
	 * JDatabase connector object.
	 *
	 * @var		object
	 * @since	1.0
	 */
	protected $_db;

	/**
	 * Should rows be tracked as ACL assets?
	 *
	 * @var		boolean
	 * @since	1.6
	 */
	protected $_trackAssets = false;

	/**
	 * The rules associated with this record.
	 *
	 * @var	JRules	A JRules object.
	 */
	protected $_rules;

	/**
	 * Indicator that the tables have been locked.
	 *
	 * @var		boolean
	 * @since	1.6
	 */
	protected $_locked = false;

	/**
	 * Object constructor to set table and key fields.  In most cases this will
	 * be overridden by child classes to explicitly set the table and key fields
	 * for a particular database table.
	 *
	 * @param	string Name of the table to model.
	 * @param	string Name of the primary key field in the table.
	 * @param	object JDatabase connector object.
	 * @since	1.0
	 */
	function __construct($table, $key, &$db)
	{
		// Set internal variables.
		$this->_tbl		= $table;
		$this->_tbl_key	= $key;
		$this->_db		= &$db;

		// Initialise the table properties.
		if ($fields = $this->getFields()) {
			foreach ($fields as $name => $v)
			{
				// Add the field if it is not already present.
				if (!property_exists($this, $name)) {
					$this->$name = null;
				}
			}
		}

		// If we are tracking assets, make sure an access field exists and initially set the default.
		if (property_exists($this, 'asset_id')) {
			jimport('joomla.access.rules');
			$this->_trackAssets = true;
		}

		// If the acess property exists, set the default.
		if (property_exists($this, 'access')) {
			$this->access = (int) JFactory::getConfig()->get('access');
		}
	}

	/**
	 * Get the columns from database table.
	 *
	 * @return	mixed	An array of the field names, or false if an error occurs.
	 */
	public function getFields()
	{
		static $cache = null;

		if ($cache === null) {
			// Lookup the fields for this table only once.
			$name	= $this->_tbl;
			$fields	= $this->_db->getTableFields($name, false);

			if (!isset($fields[$name])) {
				$e = new JException(JText::_('JLIB_DATABASE_ERROR_COLUMNS_NOT_FOUND'));
				$this->setError($e);
				return false;
			}
			$cache = $fields[$name];
		}

		return $cache;
	}

	/**
	 * Static method to get an instance of a JTable class if it can be found in
	 * the table include paths.  To add include paths for searching for JTable
	 * classes @see JTable::addIncludePath().
	 *
	 * @param	string	The type (name) of the JTable class to get an instance of.
	 * @param	string	An optional prefix for the table class name.
	 * @param	array	An optional array of configuration values for the JTable object.
	 * @return	mixed	A JTable object if found or boolean false if one could not be found.
	 * @since	1.5
	 * @link	http://docs.joomla.org/JTable/getInstance
	*/
	public static function getInstance($type, $prefix = 'JTable', $config = array())
	{
		// Sanitize and prepare the table class name.
		$type = preg_replace('/[^A-Z0-9_\.-]/i', '', $type);
		$tableClass = $prefix.ucfirst($type);

		// Only try to load the class if it doesn't already exist.
		if (!class_exists($tableClass)) {
			// Search for the class file in the JTable include paths.
			jimport('joomla.filesystem.path');

			if ($path = JPath::find(JTable::addIncludePath(), strtolower($type).'.php')) {
				// Import the class file.
				require_once $path;

				// If we were unable to load the proper class, raise a warning and return false.
				if (!class_exists($tableClass)) {
					JError::raiseWarning(0, JText::sprintf('JLIB_DATABASE_ERROR_CLASS_NOT_FOUND_IN_FILE', $tableClass));
					return false;
				}
			}
			else {
				// If we were unable to find the class file in the JTable include paths, raise a warning and return false.
				JError::raiseWarning(0, JText::sprintf('JLIB_DATABASE_ERROR_NOT_SUPPORTED_FILE_NOT_FOUND', $type));
				return false;
			}
		}

		// If a database object was passed in the configuration array use it, otherwise get the global one from JFactory.
		$db = isset($config['dbo']) ? $config['dbo'] : JFactory::getDbo();

		// Instantiate a new table class and return it.
		return new $tableClass($db);
	}

	/**
	 * Add a filesystem path where JTable should search for table class files.
	 * You may either pass a string or an array of paths.
	 *
	 * @param	mixed	A filesystem path or array of filesystem paths to add.
	 * @return	array	An array of filesystem paths to find JTable classes in.
	 * @since	1.5
	 * @link	http://docs.joomla.org/JTable/addIncludePath
	 */
	public static function addIncludePath($path = null)
	{
		// Declare the internal paths as a static variable.
		static $_paths;

		// If the internal paths have not been initialised, do so with the base table path.
		if (!isset($_paths)) {
			$_paths = array(dirname(__FILE__).DS.'table');
		}

		// Convert the passed path(s) to add to an array.
		settype($path, 'array');

		// If we have new paths to add, do so.
		if (!empty($path) && !in_array($path, $_paths)) {
			// Check and add each individual new path.
			foreach ($path as $dir)
			{
				// Sanitize path.
				$dir = trim($dir);

				// Add to the front of the list so that custom paths are searched first.
				array_unshift($_paths, $dir);
			}
		}

		return $_paths;
	}

	/**
	 * Method to compute the default name of the asset.
	 * The default name is in the form `table_name.id`
	 * where id is the value of the primary key of the table.
	 *
	 * @return	string
	 */
	protected function _getAssetName()
	{
		$k = $this->_tbl_key;
		return $this->_tbl.'.'.(int) $this->$k;
	}

	/**
	 * Method to return the title to use for the asset table.  In
	 * tracking the assets a title is kept for each asset so that there is some
	 * context available in a unified access manager.  Usually this woud just
	 * return $this->title or $this->name or whatever is being used for the
	 * primary name of the row. If this method is not overriden, the asset name is used.
	 *
	 * @return	string	The string to use as the title in the asset table.
	 * @since	1.6
	 * @link	http://docs.joomla.org/JTable/getAssetTitle
	 */
	protected function _getAssetTitle()
	{
		return $this->_getAssetName();
	}

	/**
	 * Method to get the parent asset under which to register this one.
	 * By default, all assets are registered to the ROOT node with ID 1.
	 * The extended class can define a table and id to lookup.  If the
	 * asset does not exist it will be created.
	 *
	 * @param	JTable	A JTable object for the asset parent.
	 *
	 * @return	int
	 */
	protected function _getAssetParentId($table = null, $id = null)
	{
		// For simple cases, parent to the asset root.
		if (empty($table) || empty($id)) {
			return 1;
		}

		return 1;
	}

	/**
	 * Method to get the database table name for the class.
	 *
	 * @return	string	The name of the database table being modeled.
	 * @since	1.5
	 * @link	http://docs.joomla.org/JTable/getTableName
	 */
	public function getTableName()
	{
		return $this->_tbl;
	}

	/**
	 * Method to get the primary key field name for the table.
	 *
	 * @return	string	The name of the primary key for the table.
	 * @since	1.5
	 * @link	http://docs.joomla.org/JTable/getKeyName
	 */
	public function getKeyName()
	{
		return $this->_tbl_key;
	}

	/**
	 * Method to get the JDatabase connector object.
	 *
	 * @return	object	The internal database connector object.
	 * @link	http://docs.joomla.org/JTable/getDBO
	 */
	public function getDbo()
	{
		return $this->_db;
	}

	/**
	 * Method to set the JDatabase connector object.
	 *
	 * @param	object	A JDatabase connector object to be used by the table object.
	 * @return	boolean	True on success.
	 * @link	http://docs.joomla.org/JTable/setDBO
	 */
	public function setDBO(&$db)
	{
		// Make sure the new database object is a JDatabase.
		if (!($db instanceof JDatabase)) {
			return false;
		}

		$this->_db = &$db;

		return true;
	}

	/**
	 * Method to set rules for the record.
	 *
	 * @param	mixed	A JRules object, JSON string, or array.
	 */
	function setRules($input)
	{
		if ($input instanceof JRules) {
			$this->_rules = $input;
		}
		else {
			$this->_rules = new JRules($input);
		}
	}

	/**
	 * Method to get the rules for the record.
	 *
	 * @return	JRules
	 */
	public function getRules()
	{
		return $this->_rules;
	}

	/**
	 * Method to reset class properties to the defaults set in the class
	 * definition.  It will ignore the primary key as well as any private class
	 * properties.
	 *
	 * @return	void
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/reset
	 */
	public function reset()
	{
		// Get the default values for the class from the table.
		foreach ($this->getFields() as $k => $v)
		{
			// If the property is not the primary key or private, reset it.
			if ($k != $this->_tbl_key && (strpos($k, '_') !== 0)) {
				$this->$k = $v->Default;
			}
		}
	}

	/**
	 * Method to bind an associative array or object to the JTable instance.This
	 * method only binds properties that are publicly accessible and optionally
	 * takes an array of properties to ignore when binding.
	 *
	 * @param	mixed	An associative array or object to bind to the JTable instance.
	 * @param	mixed	An optional array or space separated list of properties
	 *					to ignore while binding.
	 * @return	boolean	True on success.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/bind
	 */
	public function bind($src, $ignore = array())
	{
		// If the source value is not an array or object return false.
		if (!is_object($src) && !is_array($src)) {
			$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_BIND_FAILED_INVALID_SOURCE_ARGUMENT', get_class($this)));
			$this->setError($e);
			return false;
		}

		// If the source value is an object, get its accessible properties.
		if (is_object($src)) {
			$src = get_object_vars($src);
		}

		// If the ignore value is a string, explode it over spaces.
		if (!is_array($ignore)) {
			$ignore = explode(' ', $ignore);
		}

		// Bind the source value, excluding the ignored fields.
		foreach ($this->getProperties() as $k => $v)
		{
			// Only process fields not in the ignore array.
			if (!in_array($k, $ignore)) {
				if (isset($src[$k])) {
					$this->$k = $src[$k];
				}
			}
		}

		return true;
	}

	/**
	 * Method to load a row from the database by primary key and bind the fields
	 * to the JTable instance properties.
	 *
	 * @param	mixed	An optional primary key value to load the row by, or an array of fields to match.  If not
	 *					set the instance property value is used.
	 * @param	boolean	True to reset the default values before loading the new row.
	 * @return	boolean	True if successful. False if row not found or on error (internal error state set in that case).
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/load
	 */
	public function load($keys = null, $reset = true)
	{
		if (empty($keys)) {
			// If empty, use the value of the current key
			$keyName = $this->_tbl_key;
			$keyValue = $this->$keyName;

			// If empty primary key there's is no need to load anything
			if (empty($keyValue)) {
				return true;
			}

			$keys = array($keyName => $keyValue);
		}
		else if (!is_array($keys)) {
			// Load by primary key.
			$keys = array($this->_tbl_key => $keys);
		}

		if ($reset) {
			$this->reset();
		}

		// Initialise the query.
		$query	= $this->_db->getQuery(true);
		$query->select('*');
		$query->from($this->_tbl);
		$fields = array_keys($this->getProperties());

		foreach ($keys as $field => $value)
		{
			// Check that $field is in the table.
			if (!in_array($field, $fields)) {
				$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_CLASS_IS_MISSING_FIELD', get_class($this), $field));
				$this->setError($e);
				return false;
			}
			// Add the search tuple to the query.
			$query->where($this->_db->nameQuote($field).' = '.$this->_db->quote($value));
		}

		$this->_db->setQuery($query);
		$row = $this->_db->loadAssoc();

		// Check for a database error.
		if ($this->_db->getErrorNum()) {
			$e = new JException($this->_db->getErrorMsg());
			$this->setError($e);
			return false;
		}

		// Check that we have a result.
		if (empty($row)) {
			$e = new JException(JText::_('JLIB_DATABASE_ERROR_EMPTY_ROW_RETURNED'));
			$this->setError($e);
			return false;
		}

		// Bind the object with the row and return.
		return $this->bind($row);
	}

	/**
	 * Method to perform sanity checks on the JTable instance properties to ensure
	 * they are safe to store in the database.  Child classes should override this
	 * method to make sure the data they are storing in the database is safe and
	 * as expected before storage.
	 *
	 * @return	boolean	True if the instance is sane and able to be stored in the database.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/check
	 */
	public function check()
	{
		return true;
	}

	/**
	 * Method to store a row in the database from the JTable instance properties.
	 * If a primary key value is set the row with that primary key value will be
	 * updated with the instance property values.  If no primary key value is set
	 * a new row will be inserted into the database with the properties from the
	 * JTable instance.
	 *
	 * @param	boolean True to update fields even if they are null.
	 * @return	boolean	True on success.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/store
	 */
	public function store($updateNulls = false)
	{
		// Initialise variables.
		$k = $this->_tbl_key;

		// The asset id field is managed privately by this class.
		if ($this->_trackAssets) {
			unset($this->asset_id);
		}

		// If a primary key exists update the object, otherwise insert it.
		if ($this->$k) {
			$stored = $this->_db->updateObject($this->_tbl, $this, $this->_tbl_key, $updateNulls);
		}
		else {
			$stored = $this->_db->insertObject($this->_tbl, $this, $this->_tbl_key);
		}

		// If the store failed return false.
		if (!$stored) {
			$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_STORE_FAILED', get_class($this), $this->_db->getErrorMsg()));
			$this->setError($e);
			return false;
		}

		// If the table is not set to track assets return true.
		if (!$this->_trackAssets) {
			return true;
		}

		if ($this->_locked) {
			$this->_unlock();
		}

		//
		// Asset Tracking
		//

		$parentId	= $this->_getAssetParentId();
		$name		= $this->_getAssetName();
		$title		= $this->_getAssetTitle();

		$asset	= JTable::getInstance('Asset');
		$asset->loadByName($name);

		// Re-inject the asset id.
		$this->asset_id = $asset->id;

		// Check for an error.
		if ($error = $asset->getError()) {
			$this->setError($error);
			return false;
		}

		// Specify how a new or moved node asset is inserted into the tree.
		if (empty($this->asset_id) || $asset->parent_id != $parentId) {
			$asset->setLocation($parentId, 'last-child');
		}

		// Prepare the asset to be stored.
		$asset->parent_id	= $parentId;
		$asset->name		= $name;
		$asset->title		= $title;

		if ($this->_rules instanceof JRules) {
			$asset->rules = (string) $this->_rules;
		}

		if (!$asset->check() || !$asset->store($updateNulls)) {
			$this->setError($asset->getError());
			return false;
		}

		if (empty($this->asset_id)) {
			// Update the asset_id field in this table.
			$this->asset_id = (int) $asset->id;

			$query = $this->_db->getQuery(true);
			$query->update($this->_db->nameQuote($this->_tbl));
			$query->set('asset_id = '.(int) $this->asset_id);
			$query->where($this->_db->nameQuote($k).' = '.(int) $this->$k);
			$this->_db->setQuery($query);

			if (!$this->_db->query()) {
				$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_STORE_FAILED_UPDATE_ASSET_ID', $this->_db->getErrorMsg()));
				$this->setError($e);
				return false;
			}
		}

		return true;
	}

	/**
	 * Method to provide a shortcut to binding, checking and storing a JTable
	 * instance to the database table.  The method will check a row in once the
	 * data has been stored and if an ordering filter is present will attempt to
	 * reorder the table rows based on the filter.  The ordering filter is an instance
	 * property name.  The rows that will be reordered are those whose value matches
	 * the JTable instance for the property specified.
	 *
	 * @param	mixed	An associative array or object to bind to the JTable instance.
	 * @param	string	Filter for the order updating
	 * @param	mixed	An optional array or space separated list of properties
	 *					to ignore while binding.
	 * @return	boolean	True on success.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/save
	 */
	public function save($src, $orderingFilter = '', $ignore = '')
	{
		// Attempt to bind the source to the instance.
		if (!$this->bind($src, $ignore)) {
			return false;
		}

		// Run any sanity checks on the instance and verify that it is ready for storage.
		if (!$this->check()) {
			return false;
		}

		// Attempt to store the properties to the database table.
		if (!$this->store()) {
			return false;
		}

		// Attempt to check the row in, just in case it was checked out.
		if (!$this->checkin()) {
			return false;
		}

		// If an ordering filter is set, attempt reorder the rows in the table based on the filter and value.
		if ($orderingFilter) {
			$filterValue = $this->$orderingFilter;
			$this->reorder($orderingFilter ? $this->_db->nameQuote($orderingFilter).' = '.$this->_db->Quote($filterValue) : '');
		}

		// Set the error to empty and return true.
		$this->setError('');

		return true;
	}

	/**
	 * Method to delete a row from the database table by primary key value.
	 *
	 * @param	mixed	An optional primary key value to delete.  If not set the
	 *					instance property value is used.
	 * @return	boolean	True on success.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/delete
	 */
	public function delete($pk = null)
	{
		// Initialise variables.
		$k = $this->_tbl_key;
		$pk = (is_null($pk)) ? $this->$k : $pk;

		// If no primary key is given, return false.
		if ($pk === null) {
			$e = new JException(JText::_('JLIB_DATABASE_ERROR_NULL_PRIMARY_KEY'));
			$this->setError($e);
			return false;
		}

		// If tracking assets, remove the asset first.
		if ($this->_trackAssets) {
			// Get and the asset name.
			$this->$k	= $pk;
			$name		= $this->_getAssetName();
			$asset		= JTable::getInstance('Asset');

			if ($asset->loadByName($name)) {
				if (!$asset->delete()) {
					$this->setError($asset->getError());
					return false;
				}
			}
			else {
				$this->setError($asset->getError());
				return false;
			}
		}

		// Delete the row by primary key.
		$query = $this->_db->getQuery(true);
		$query->delete();
		$query->from($this->_tbl);
		$query->where($this->_tbl_key.' = '.$this->_db->quote($pk));
		$this->_db->setQuery($query);

		// Check for a database error.
		if (!$this->_db->query()) {
			$e = new JException(JText::_('JLIB_DATABASE_ERROR_DELETE_FAILED', get_class($this), $this->_db->getErrorMsg()));
			$this->setError($e);
			return false;
		}

		return true;
	}

	/**
	 * Method to check a row out if the necessary properties/fields exist.  To
	 * prevent race conditions while editing rows in a database, a row can be
	 * checked out if the fields 'checked_out' and 'checked_out_time' are available.
	 * While a row is checked out, any attempt to store the row by a user other
	 * than the one who checked the row out should be held until the row is checked
	 * in again.
	 *
	 * @param	integer	The Id of the user checking out the row.
	 * @param	mixed	An optional primary key value to check out.  If not set
	 *					the instance property value is used.
	 * @return	boolean	True on success.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/checkOut
	 */
	public function checkOut($userId, $pk = null)
	{
		// If there is no checked_out or checked_out_time field, just return true.
		if (!property_exists($this, 'checked_out') || !property_exists($this, 'checked_out_time')) {
			return true;
		}

		// Initialise variables.
		$k = $this->_tbl_key;
		$pk = (is_null($pk)) ? $this->$k : $pk;

		// If no primary key is given, return false.
		if ($pk === null) {
			$e = new JException(JText::_('JLIB_DATABASE_ERROR_NULL_PRIMARY_KEY'));
			$this->setError($e);
			return false;
		}

		// Get the current time in MySQL format.
		$time = JFactory::getDate()->toMysql();

		// Check the row out by primary key.
		$query = $this->_db->getQuery(true);
		$query->update($this->_tbl);
		$query->set($this->_db->nameQuote('checked_out').' = '.(int) $userId);
		$query->set($this->_db->nameQuote('checked_out_time').' = '.$this->_db->quote($time));
		$query->where($this->_tbl_key.' = '.$this->_db->quote($pk));
		$this->_db->setQuery($query);

		if (!$this->_db->query()) {
			$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_CHECKOUT_FAILED', get_class($this), $this->_db->getErrorMsg()));
			$this->setError($e);
			return false;
		}

		// Set table values in the object.
		$this->checked_out = (int) $userId;
		$this->checked_out_time = $time;

		return true;
	}

	/**
	 * Method to check a row in if the necessary properties/fields exist.  Checking
	 * a row in will allow other users the ability to edit the row.
	 *
	 * @param	mixed	An optional primary key value to check out.  If not set
	 *					the instance property value is used.
	 * @return	boolean	True on success.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/checkIn
	 */
	public function checkIn($pk = null)
	{
		// If there is no checked_out or checked_out_time field, just return true.
		if (!property_exists($this, 'checked_out') || !property_exists($this, 'checked_out_time')) {
			return true;
		}

		// Initialise variables.
		$k = $this->_tbl_key;
		$pk = (is_null($pk)) ? $this->$k : $pk;

		// If no primary key is given, return false.
		if ($pk === null) {
			$e = new JException(JText::_('JLIB_DATABASE_ERROR_NULL_PRIMARY_KEY'));
			$this->setError($e);
			return false;
		}

		// Check the row in by primary key.
		$query = $this->_db->getQuery(true);
		$query->update($this->_tbl);
		$query->set($this->_db->nameQuote('checked_out').' = 0');
		$query->set($this->_db->nameQuote('checked_out_time').' = '.$this->_db->quote($this->_db->getNullDate()));
		$query->where($this->_tbl_key.' = '.$this->_db->quote($pk));
		$this->_db->setQuery($query);

		// Check for a database error.
		if (!$this->_db->query()) {
			$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_CHECKIN_FAILED', get_class($this), $this->_db->getErrorMsg()));
			$this->setError($e);
			return false;
		}

		// Set table values in the object.
		$this->checked_out = 0;
		$this->checked_out_time = '';

		return true;
	}

	/**
	 * Method to increment the hits for a row if the necessary property/field exists.
	 *
	 * @param	mixed	An optional primary key value to increment.  If not set
	 *					the instance property value is used.
	 * @return	boolean	True on success.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/hit
	 */
	public function hit($pk = null)
	{
		// If there is no hits field, just return true.
		if (!property_exists($this, 'hits')) {
			return true;
		}

		// Initialise variables.
		$k = $this->_tbl_key;
		$pk = (is_null($pk)) ? $this->$k : $pk;

		// If no primary key is given, return false.
		if ($pk === null) {
			return false;
		}

		// Check the row in by primary key.
		$query = $this->_db->getQuery(true);
		$query->update($this->_tbl);
		$query->set($this->_db->nameQuote('hits').' = ('.$this->_db->nameQuote('hits').' + 1)');
		$query->where($this->_tbl_key.' = '.$this->_db->quote($pk));
		$this->_db->setQuery($query);

		// Check for a database error.
		if (!$this->_db->query()) {
			$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_HIT_FAILED', get_class($this), $this->_db->getErrorMsg()));
			$this->setError($e);
			return false;
		}

		// Set table values in the object.
		$this->hits++;

		return true;
	}

	/**
	 * TODO: This either needs to be static or not.
	 *
	 * Method to determine if a row is checked out and therefore uneditable by
	 * a user.  If the row is checked out by the same user, then it is considered
	 * not checked out -- as the user can still edit it.
	 *
	 * @param	integer	The userid to preform the match with, if an item is checked
	 *					out by this user the function will return false.
	 * @param	integer	The userid to perform the match against when the function
	 *					is used as a static function.
	 * @return	boolean	True if checked out.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/isCheckedOut
	 */
	public function isCheckedOut($with = 0, $against = null)
	{
		// Handle the non-static case.
		if (isset($this) && ($this instanceof JTable) && is_null($against)) {
			$against = $this->get('checked_out');
		}

		// The item is not checked out or is checked out by the same user.
		if (!$against || ($against == $with)) {
			return false;
		}

		$db = JFactory::getDBO();
		$db->setQuery(
			'SELECT COUNT(userid)' .
			' FROM `#__session`' .
			' WHERE `userid` = '.(int) $against
		);
		$checkedOut = (boolean) $db->loadResult();

		// If a session exists for the user then it is checked out.
		return $checkedOut;
	}

	/**
	 * Method to get the next ordering value for a group of rows defined by an SQL WHERE clause.
	 * This is useful for placing a new item last in a group of items in the table.
	 *
	 * @param	string	WHERE clause to use for selecting the MAX(ordering) for the table.
	 * @return	mixed	Boolean false an failure or the next ordering value as an integer.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/getNextOrder
	 */
	public function getNextOrder($where = '')
	{
		// If there is no ordering field set an error and return false.
		if (!property_exists($this, 'ordering')) {
			$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_CLASS_DOES_NOT_SUPPORT_ORDERING', get_class($this)));
			$this->setError($e);
			return false;
		}

		// Get the largest ordering value for a given where clause.
		$query = $this->_db->getQuery(true);
		$query->select('MAX(ordering)');
		$query->from($this->_tbl);

		if ($where) {
			$query->where($where);
		}

		$this->_db->setQuery($query);
		$max = (int) $this->_db->loadResult();

		// Check for a database error.
		if ($this->_db->getErrorNum()) {
			$e = new JException(
				JText::sprintf('JLIB_DATABASE_ERROR_GET_NEXT_ORDER_FAILED', get_class($this), $this->_db->getErrorMsg())
			);
			$this->setError($e);

			return false;
		}

		// Return the largest ordering value + 1.
		return ($max + 1);
	}

	/**
	 * Method to compact the ordering values of rows in a group of rows
	 * defined by an SQL WHERE clause.
	 *
	 * @param	string	WHERE clause to use for limiting the selection of rows to
	 *					compact the ordering values.
	 * @return	mixed	Boolean true on success.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/reorder
	 */
	public function reorder($where = '')
	{
		// If there is no ordering field set an error and return false.
		if (!property_exists($this, 'ordering')) {
			$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_CLASS_DOES_NOT_SUPPORT_ORDERING', get_class($this)));
			$this->setError($e);
			return false;
		}

		// Initialise variables.
		$k = $this->_tbl_key;

		// Get the primary keys and ordering values for the selection.
		$query = $this->_db->getQuery(true);
		$query->select($this->_tbl_key.', ordering');
		$query->from($this->_tbl);
		$query->where('ordering >= 0');
		$query->order('ordering');

		// Setup the extra where and ordering clause data.
		if ($where) {
			$query->where($where);
		}

		$this->_db->setQuery($query);
		$rows = $this->_db->loadObjectList();

		// Check for a database error.
		if ($this->_db->getErrorNum()) {
			$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_REORDER_FAILED', get_class($this), $this->_db->getErrorMsg()));
			$this->setError($e);

			return false;
		}

		// Compact the ordering values.
		foreach ($rows as $i => $row)
		{
			// Make sure the ordering is a positive integer.
			if ($row->ordering >= 0) {
				// Only update rows that are necessary.
				if ($row->ordering != $i+1) {
					// Update the row ordering field.
					$query = $this->_db->getQuery(true);
					$query->update($this->_tbl);
					$query->set('ordering = '.($i+1));
					$query->where($this->_tbl_key.' = '.$this->_db->quote($row->$k));
					$this->_db->setQuery($query);

					// Check for a database error.
					if (!$this->_db->query()) {
						$e = new JException(
							JText::sprintf(
								'JLIB_DATABASE_ERROR_REORDER_UPDATE_ROW_FAILED', get_class($this), $i, $this->_db->getErrorMsg()
							)
						);
						$this->setError($e);

						return false;
					}
				}
			}
		}

		return true;
	}

	/**
	 * Method to move a row in the ordering sequence of a group of rows defined by an SQL WHERE clause.
	 * Negative numbers move the row up in the sequence and positive numbers move it down.
	 *
	 * @param	integer	The direction and magnitude to move the row in the ordering sequence.
	 * @param	string	WHERE clause to use for limiting the selection of rows to compact the
	 *					ordering values.
	 * @return	mixed	Boolean true on success.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/move
	 */
	public function move($delta, $where = '')
	{
		// If there is no ordering field set an error and return false.
		if (!property_exists($this, 'ordering')) {
			$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_CLASS_DOES_NOT_SUPPORT_ORDERING', get_class($this)));
			$this->setError($e);
			return false;
		}

		// If the change is none, do nothing.
		if (empty($delta)) {
			return true;
		}

		// Initialise variables.
		$k		= $this->_tbl_key;
		$row	= null;
		$query	= $this->_db->getQuery(true);

		// Select the primary key and ordering values from the table.
		$query->select($this->_tbl_key.', ordering');
		$query->from($this->_tbl);

		// If the movement delta is negative move the row up.
		if ($delta < 0) {
			$query->where('ordering < '.(int) $this->ordering);
			$query->order('ordering DESC');
		}
		// If the movement delta is positive move the row down.
		elseif ($delta > 0) {
			$query->where('ordering > '.(int) $this->ordering);
			$query->order('ordering ASC');
		}

		// Add the custom WHERE clause if set.
		if ($where) {
			$query->where($where);
		}

		// Select the first row with the criteria.
		$this->_db->setQuery($query, 0, 1);
		$row = $this->_db->loadObject();

		// If a row is found, move the item.
		if (!empty($row)) {
			// Update the ordering field for this instance to the row's ordering value.
			$query = $this->_db->getQuery(true);
			$query->update($this->_tbl);
			$query->set('ordering = '.(int) $row->ordering);
			$query->where($this->_tbl_key.' = '.$this->_db->quote($this->$k));
			$this->_db->setQuery($query);

			// Check for a database error.
			if (!$this->_db->query()) {
				$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_MOVE_FAILED', get_class($this), $this->_db->getErrorMsg()));
				$this->setError($e);

				return false;
			}

			// Update the ordering field for the row to this instance's ordering value.
			$query = $this->_db->getQuery(true);
			$query->update($this->_tbl);
			$query->set('ordering = '.(int) $this->ordering);
			$query->where($this->_tbl_key.' = '.$this->_db->quote($row->$k));
			$this->_db->setQuery($query);

			// Check for a database error.
			if (!$this->_db->query()) {
				$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_MOVE_FAILED', get_class($this), $this->_db->getErrorMsg()));
				$this->setError($e);

				return false;
			}

			// Update the instance value.
			$this->ordering = $row->ordering;
		}
		else {
			// Update the ordering field for this instance.
			$query = $this->_db->getQuery(true);
			$query->update($this->_tbl);
			$query->set('ordering = '.(int) $this->ordering);
			$query->where($this->_tbl_key.' = '.$this->_db->quote($this->$k));
			$this->_db->setQuery($query);

			// Check for a database error.
			if (!$this->_db->query()) {
				$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_MOVE_FAILED', get_class($this), $this->_db->getErrorMsg()));
				$this->setError($e);

				return false;
			}
		}

		return true;
	}

	/**
	 * Method to set the publishing state for a row or list of rows in the database
	 * table.  The method respects checked out rows by other users and will attempt
	 * to checkin rows that it can after adjustments are made.
	 *
	 * @param	mixed	An optional array of primary key values to update.  If not
	 *					set the instance property value is used.
	 * @param	integer The publishing state. eg. [0 = unpublished, 1 = published]
	 * @param	integer The user id of the user performing the operation.
	 * @return	boolean	True on success.
	 * @since	1.0.4
	 * @link	http://docs.joomla.org/JTable/publish
	 */
	public function publish($pks = null, $state = 1, $userId = 0)
	{
		// Initialise variables.
		$k = $this->_tbl_key;

		// Sanitize input.
		JArrayHelper::toInteger($pks);
		$userId = (int) $userId;
		$state  = (int) $state;

		// If there are no primary keys set check to see if the instance key is set.
		if (empty($pks)) {
			if ($this->$k) {
				$pks = array($this->$k);
			}
			// Nothing to set publishing state on, return false.
			else {
				$e = new JException(JText::_('JLIB_DATABASE_ERROR_NO_ROWS_SELECTED'));
				$this->setError($e);

				return false;
			}
		}

		// Update the publishing state for rows with the given primary keys.
		$query = $this->_db->getQuery(true);
		$query->update($this->_tbl);
		$query->set('published = '.(int) $state);

		// Determine if there is checkin support for the table.
		if (property_exists($this, 'checked_out') || property_exists($this, 'checked_out_time')) {
			$query->where('(checked_out = 0 OR checked_out = '.(int) $userId.')');
			$checkin = true;
		}
		else {
			$checkin = false;
		}

		// Build the WHERE clause for the primary keys.
		$query->where($k.' = '.implode(' OR '.$k.' = ', $pks));

		$this->_db->setQuery($query);

		// Check for a database error.
		if (!$this->_db->query()) {
			$e = new JException(JText::sprintf('JLIB_DATABASE_ERROR_PUBLISH_FAILED', get_class($this), $this->_db->getErrorMsg()));
			$this->setError($e);

			return false;
		}

		// If checkin is supported and all rows were adjusted, check them in.
		if ($checkin && (count($pks) == $this->_db->getAffectedRows())) {
			// Checkin the rows.
			foreach($pks as $pk)
			{
				$this->checkin($pk);
			}
		}

		// If the JTable instance value is in the list of primary keys that were set, set the instance.
		if (in_array($this->$k, $pks)) {
			$this->published = $state;
		}

		$this->setError('');
		return true;
	}

	/**
	 * Generic check for whether dependancies exist for this object in the database schema
	 *
	 * Can be overloaded/supplemented by the child class
	 *
	 * @deprecated
	 * @param	mixed	An optional primary key value check the row for.  If not
	 *					set the instance property value is used.
	 * @param	array	An optional array to compiles standard joins formatted like:
	 *					[label => 'Label', name => 'table name' , idfield => 'field', joinfield => 'field']
	 * @return	boolean	True on success.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/canDelete
	 */
	public function canDelete($pk = null, $joins = null)
	{
		// Initialise variables.
		$k = $this->_tbl_key;
		$pk = (is_null($pk)) ? $this->$k : $pk;

		// If no primary key is given, return false.
		if ($pk === null) {
			return false;
		}

		if (is_array($joins)) {
			// Get a query object.
			$query	= $this->_db->getQuery(true);

			// Setup the basic query.
			$query->select('`'.$this->_tbl_key.'`');
			$query->from('`'.$this->_tbl.'`');
			$query->where('`'.$this->_tbl_key.'` = '.$this->_db->quote($this->$k));
			$query->group('`'.$this->_tbl_key.'`');

			// For each join add the select and join clauses to the query object.
			foreach($joins as $table)
			{
				$query->select('COUNT(DISTINCT '.$table['idfield'].') AS '.$table['idfield']);
				$query->join('LEFT', $table['name'].' ON '.$table['joinfield'].' = '.$k);
			}

			// Get the row object from the query.
			$this->_db->setQuery((string) $query, 0, 1);
			$row = $this->_db->loadObject();

			// Check for a database error.
			if ($this->_db->getErrorNum()) {
				$this->setError($this->_db->getErrorMsg());

				return false;
			}

			$msg = array();
			$i = 0;

			foreach ($joins as $table) {
				$k = $table['idfield'] . $i;

				if ($obj->$k) {
					$msg[] = JText::_($table['label']);
				}

				$i++;
			}

			if (count($msg)) {
				$this->setError("noDeleteRecord" . ": " . implode(', ', $msg));

				return false;
			}
			else {
				return true;
			}
		}

		return true;
	}

	/**
	 * Method to export the JTable instance properties to an XML string.
	 *
	 * @deprecated
	 * @param	boolean	True to map foreign keys to text values.
	 * @return	string	XML string representation of the instance.
	 * @since	1.0
	 * @link	http://docs.joomla.org/JTable/toXML
	 */
	public function toXML($mapKeysToText=false)
	{
		// Initialise variables.
		$xml = array();
		$map = $mapKeysToText ? ' mapkeystotext="true"' : '';

		// Open root node.
		$xml[] = '<record table="'.$this->_tbl.'"'.$map.'>';

		// Get the publicly accessible instance properties.
		foreach (get_object_vars($this) as $k => $v)
		{
			// If the value is null or non-scalar, or the field is internal ignore it.
			if (!is_scalar($v) || ($v === null) || ($k[0] == '_')) {
				continue;
			}

			$xml[] = '	<'.$k.'><![CDATA['.$v.']]></'.$k.'>';
		}

		// Close root node.
		$xml[] = '</record>';

		// Return the XML array imploded over new lines.
		return implode("\n", $xml);
	}

	/**
	 * Method to lock the database table for writing.
	 *
	 * @return	boolean	True on success.
	 * @since	1.6
	 */
	protected function _lock()
	{
		// Lock the table for writing.
		$this->_db->setQuery('LOCK TABLES `'.$this->_tbl.'` WRITE');
		$this->_db->query();

		// Check for a database error.
		if ($this->_db->getErrorNum()) {
			$this->setError($this->_db->getErrorMsg());

			return false;
		}

		$this->_locked = true;

		return true;
	}

	/**
	 * Method to unlock the database table for writing.
	 *
	 * @return	boolean	True on success.
	 * @since	1.6
	 */
	protected function _unlock()
	{
		// Unlock the table.
		$this->_db->setQuery('UNLOCK TABLES');
		$this->_db->query();

		// Check for a database error.
		if ($this->_db->getErrorNum()) {
			$this->setError($this->_db->getErrorMsg());

			return false;
		}

		$this->_locked = false;

		return true;
	}
}