<?php
/**
 * Datasource abstraction
 * 
 * @author gERD Schaufelberger <gerd@exit0.net>
 * @copyright 2004 by gERD Schaufelberger
 * @package wombatSite
 * @subpackage datasource
 */
 
/**
 * wbDatasource
 * 
 * Abstraction layer for (MySQL) Databse-Connections
 *
 * @version 1.0.2
 * @package wombatSite
 * @subpackage datasource
 */
class wbDatasource
{
   /**
	* data connection PEAR::db-object 
	* @var	object	$_dc
	*/
	var	$_dc = null;
	
   /**
	* session object
	* @var	object	$_sess
	*/
	var	$_sess = null;
	
   /**
	* callback object
	* @var	object	$_callback
	*/
	var	$_callback = null;
	
   /**
	* knwon tables
	*
	* @access private
	* @var	array	$_tables
	*/
	var	$_tables = array();
		
   /**
 	* @access private
 	* @var	int	$_pager page offset
 	*/
 	var	$_pager = null;
	
   /**
 	* @access private
 	* @var	int	$_debug whether datasource runs in debug mode
 	*/
 	var	$_debug	=	false;
	
   /**
	* constructor creates datasource
	*
	* @access public
	* @param array $tableSepcs table configuration
	*/
    function __construct( &$tableSpecs  )
	{
		// load dataconnection
		$this->_dc		=&	wbFactory::singleton( 'DB' );
		$this->_sess	=&	wbFactory::singleton( 'patSession' );
		$conf			=&	wbFactory::singleton( 'patConfiguration' );
		
		// load config
		$conf->loadCachedConfig( $tableSpecs );
		$this->_tables	=	$conf->getConfigValue( 'tables' );
    }

   /**
	* constructor wrapper for PHP4
	*
	* @access public
	* @param array $tableSepcs table configuration
	* @see __contruct()
	*/
    function wbDatasource( &$tableSpecs  )
    {
		$this->__construct( $tableSpecs  );
    }

   /**
    * set reference to callback object
	*
	* @access private
	* @param object $callback
	* @return boolean $result true on success
	*/
    function setCallback( &$callback )
    {
		// set callback-object
		$this->_callback	=&	$callback;
		return true;
    }

   /**
	* switch debugging mode on or of
	*
	* @access private
	* @param int $switch 1|0 
	* @return boolean $result true on success
	*/
    function setDebug( $switch = 0 )
    {
		if( !$switch )
		{
			$this->_debug	=	false;
			return true;
		}
		
		$this->_debug		=	true;
        return true;
    }

   /**
	* set options for a table
	*
	* @access public
	* @param array $options multiple options for multiple tables
	* @return boolean $result true on success
	*/
    function setOptions( $options )
    {
		foreach( $options as $table => $opts )
		{
			foreach( $opts as $key => $value )
			{
				$this->_tables[$table][$key]	=	$value;
			}
		}
        return true;
    }
	
   /**
	* getPrimaryKey
	*
	* @access private
	* @param string $table table name
	* @return string $key named primary key
	*/
    function getPrimaryKey( $table )
    {
		return $this->_tables[$table]['primary'];
    }
	
   /**
	* count entries of a table, matching the clause
	*
	* @access private
	* @param string $table named table in db
    * @param int $foreign
	* @param array $clause key-value pairs
	* @return int $result number of entries on success
	*/
    function count( $table, $foreign = null, $clause = null )
    {
        if( !is_array( $clause ) ) {
            $clause =   array();
        }
		
        $primary	=	$this->_tables[$table]['primary'];
		$query		=	'SELECT COUNT( '. $this->_tables[$table]['table'] . '.' .  $primary .' ) '
						.'FROM ' . $this->_tables[$table]['table'];

        // add foreign key
        if( $foreign !== null && isset( $this->_tables[$table]['foreign'] ) ) {
            $fKey   =   $this->_tables[ $this->_tables[$table]['foreign'] ]['primary'];
            array_push( $clause,  array( 'field' => $fKey, 'value' => $foreign ) );
        }
        
		// skip entries marked as deleted.
		if( isset( $this->_tables[$table]['delete'] ) )
		{
			list( $key, $value )	=	explode( '=', $this->_tables[$table]['delete'] );
			array_push( $clause, array( 'relation' => 'not_in_set', 'field' => $key, 'value' => $value ) );
		}
		
		if( !empty( $clause ) )
		{
			$where	=	array();
			$this->_clause2Where( $table, $clause, $where );
			$query	.=	' WHERE ' . implode( ' AND ', $where );
		}
		
		$this->_addDebugMessage( $query, 'Count SQL' );
		$result	=	$this->_dc->getOne( $query );
		if( PEAR::isError( $result ) )
		{
			return patErrorManager::raiseError( 
						'wbDatasource:1',
						'Counting entries failed',
						'Query: ' . $query 
					 );
		}
		
        return $result;
    }
	
   /**
    * recieve field names for dublicate entries 
	* 
	* @access public
	* @param string $table	named table to get data from
	* @param int $id id of entry
	* @param array &$data associative array to be saved to database
	* @return array $result empty array if no dublicates were found, array containing fields if copies were found
	*/
    function getDublicates( $table, $id, &$data )
    {
		$dubs	=	array();
	
		// check for copies
		if( !isset( $this->_tables[$table]['avoiddublicate'] ) )
		{
			return $dubs;
		}
		
		$primary	=	$this->_tables[$table]['primary'];		
		$dFields	=	explode( ',', $this->_tables[$table]['avoiddublicate'] );

		$where	=	array( $this->_tables[$table]['table'] . '.%s LIKE %s' );
		
		if( $id != 'new' )
		{
			array_push( $where, $this->_tables[$table]['table'] . '.' . $primary . '!=' . $this->_dc->quote( $id ) );
		}
		
		if( isset( $this->_tables[$table]['foreign'] ) )
		{
			$fTable		=	$this->_tables[$table]['foreign'];
			$fPrimary	=	$this->_tables[$fTable]['primary'];
			$fKey		=	$data[$fPrimary];
			array_push( $where, $this->_tables[$table]['table'] . '.' . $fPrimary . '=' . $this->_dc->quote( $fKey ) );
		}
		
		
		// skip entries marked as deleted.	
		if( isset( $this->_tables[$table]['delete'] ) )
		{
			list( $key, $value )	=	explode( '=', $this->_tables[$table]['delete'] );
			array_push( $where, 'NOT FIND_IN_SET( '. $this->_dc->quote( $value ) . ', ' . $this->_tables[$table]['table'] . '.' .  $key . ' )' );
		}
		
		// check each field
		$query	=	'SELECT '. $primary 
				.	' FROM ' . $this->_tables[$table]['table'] 
				.	' WHERE ' . implode( ' AND ', $where );
		
		// check for dublicates		
		foreach( $dFields as $df )
		{
			if( !array_key_exists( $df, $data ) )
			{
				continue;
			}
			$q	=	sprintf( $query, $df, $this->_dc->quote( $data[$df] ) );
		
			$result	=	$this->_dc->query( $q );
			if( DB::isError( $result ) )
			{
				return patErrorManager::raiseError(
											'wbDatasource:8',
											'Recieving dublicates failed!',
											'Query failed: ' . $q
										);
			}
			
			if( $result->numRows() > 0 )
			{
				array_push( $dubs, $df );
			}
		}
		
		return $dubs;
    }
	
   /**
	* save entry in table
	*
	* @access private
	* @param string $table named table in db
	* @param mixed $key primary id or 'new' for a new record
	* @param array &$data associative array to be saved to database
	* @param array $clause key-value pairs for delete
	* @return int $result primary key on success ucuoError-Object on error
	*/
    function save( $table, $key, &$data, $clause = array() )
    {
		// no data, no save
		if( empty( $data) )
		{
			return true;
		}
		
		if( empty( $clause ) && $key == null )
		{
			$msg	=	sprintf( 'Need a key or a clause! Table: "%s", Key: "%s".', $table, $key );
			$this->_addDebugMessage( $msg, 'Save data failed' );
			return patErrorManager::raiseError(
											'wbDatasource:6',
											'Save data failed!',
											'No Key and no clause set'
										);
		}
	
		$dubs	=	$this->getDublicates( $table, $key, $data );
		if( !empty( $dubs ) )
		{
			$msg	=	sprintf( 'Table: "%s", Key: "%s", dublicated fields: "%s".', $table, $key, implode( '","', $dubs ) );
			$this->_addDebugMessage( $msg, 'Save data failed' );
		
			return patErrorManager::raiseNotice(
											'wbDatasource:7',
											'Save data failed!',
											'Dublicate entry found'
										);
		}
		
		if( $this->_useCallback( $table, 'save' ) )
		{
			$result	=	$this->_callback->callForSave( $table, $data, $key );
			if( patErrorManager::isError( $result ) )
			{
				return $result;
			}
		}

		// build query	
		$primary	=	$this->_tables[$table]['primary'];
		
		$query	=	'UPDATE ';
		$where	=	array();
		if( $key == 'new' )
		{
			$key			=	$this->_dc->nextId( $this->_tables[$table]['table'] );
			$data[$primary]	=	$key;
			$query			=	'INSERT INTO ';
		}
		else if( $key != null )
		{
			array_push( $where, $this->_tables[$table]['table'] . '.' . $primary . '=' . $this->_dc->quote( $key ) );
		}
		
		$this->_clause2Where( $table, $clause, $where );
		
		$set	=	array();
		foreach( $data as $field => $value )
		{
			array_push( $set, $this->_tables[$table]['table'] . '.' . $field . '=' . $this->_dc->quote( $value ) );
		}
		
		$query	.=	$this->_tables[$table]['table'] . ' SET ' . implode( ', ', $set );
		if( !empty( $where ) ) 
		{
			$query	.=	' WHERE '. implode( ' AND ', $where );
		}
		
		$this->_addDebugMessage( $query, 'Save data SQL' );
		$result	=	$this->_dc->query( $query );
		if( DB::isError( $result ) )
		{
			return patErrorManager::raiseError(
											'wbDatasource:7',
											'Save data failed!',
											'Query failed: ' . $query 
										);
		}
        return $key;
    }

   /**
	* delete entry/ies from db
	*
	* @access public
	* @param string $table	named table in db
	* @param mixed $key null if no key is used, primary key otherwise
	* @param array $clause additional clause
	* @return int $result number of rows deletete
	*/
    function delete( $table, $key, $clause = array() )
    {
		if( $key === null && empty( $clause ) )
		{
			return patErrorManager::raiseWarning(
												'wbDatasource:10',
												'Delete failed',
												'Need either primary or clause or both - nothing found!'
											);
		}
		
		// use callback
		if( $this->_useCallback( $table, 'delete' ) )
		{
			$result	=	$this->_callback->callForDelete( $table, $clause, $key );
			if( patErrorManager::isError( $result ) )
			{
				return $result;
			}
		}

		$primary	=	$this->_tables[$table]['primary'];
		$where		=	array();
		if( $key != null )
		{
			array_push( $where, $primary . '=' . $this->_dc->quote( $key ) );
		}
		
		if( !empty( $clause ) )
		{
			$this->_clause2Where( $table, $clause, $where );
		}
		
		// delete linked data
		$foreign	=	array();
		foreach( $this->_tables as $tab => $tabConf )
		{
			if( isset( $tabConf['foreign'] ) && $tabConf['foreign'] === $table )
			{
				array_push( $foreign, $tab );
			}
		}
		
		if( !empty( $foreign ) )
		{
			$query	=	'SELECT ' . $primary 
					.	' FROM ' . $this->_tables[$table]['table']
					.	' WHERE ' . implode( ' AND ', $where );
			$keys	=	$this->_dc->getCol( $query );
			if( DB::isError( $keys ) )
			{
				return patErrorManager::raiseWarning(
												'wbDatasource:12',
												'Delete failed, could not select keys',
												'Failed sending query: ' . $query
											);
			}
			
			// get clause for delete entries in foreign table
			$clause	=	array( 
					array( 'field' => $primary ),
				);
			foreach( $foreign as $f )
			{
				foreach( $keys as $k )
				{
					$clause[0]['value']	=	$k;
					$this->delete( $f, null, $clause );
				}
			}
		}
		
		// finally delete all entries in primary table
		if( isset( $this->_tables[$table]['delete'] ) )
		{
			list( $key, $value )	=	explode( '=', $this->_tables[$table]['delete'] );
			$query	=	'UPDATE ' . $this->_tables[$table]['table']
					.	' SET ' . $key . '=CONCAT( '. $key .' ,'. $this->_dc->quote( ',' . $value  ) .'  )'
					.	' WHERE ' . implode( ' AND ', $where );	
		}
		else
		{
			$query		=	'DELETE FROM ' . $this->_tables[$table]['table'] . ' WHERE ' . implode( ' AND ', $where );
		}
		
		$result		=	$this->_dc->query( $query );
		$this->_addDebugMessage( $query, 'Delete data SQL' );
		if( DB::isError( $result ) )
		{
			return patErrorManager::raiseWarning(
												'wbDatasource:11',
												'Delete failed',
												'Failed sending query: ' . $query
											);
		}
        return 1;
    }


   /**
	* recieve a single entry from database
	*
	* @access public
	* @param string $table	named table in db
	* @param int $id id of entry or "first" or "last"
	* @param int $foreign if of foreign key
	* @param array $clause additional clause
	* @return array $entry assiciative array containing entry from db or number of rows if not one
	*/
    function getEntry( $table, $id, $foreign = null, $clause = array() )
    {
		$primary	=	$this->_tables[$table]['primary'];

        $limit  =   '';
		$where	=	array( 1 );
		if( $id !== null ) {
            $this->_addDebugMessage( 'Select from "'. $table .'" by id "'. $id .'"', 'Get Entry' );
            switch( $id ) {
                case 'random':
                    $count  =   $this->count( $table, $foreign, $clause );
                    $offset =   rand( 0, ( $count - 1 ) );
                    $limit  =   $offset . ',1';
                    break;

                case 'first':
                    $limit  =   '0,1';
                    break;

                case 'last':
                    $limit  =   '-1,1';
                    break;
                    
                default:
                    // normal id 
                    array_push( $where, $primary . '=' . $this->_dc->quote( $id ) );
                    break;
            }
		}
		
		if( $foreign !== null && isset( $this->_tables[$table]['foreign'] ) ) {
			$fKey	=	$this->_tables[ $this->_tables[$table]['foreign'] ]['primary'];
			array_push( $clause,  array( 'field' => $fKey, 'value' => $foreign ) );
		}
		
		// skip entries marked as deleted.	
		if( isset( $this->_tables[$table]['delete'] ) ) {
			list( $key, $value )	=	explode( '=', $this->_tables[$table]['delete'] );
			array_push( $clause, array( 'relation' => 'not_in_set', 'field' => $key, 'value' => $value ) );
		}
		
		$this->_clause2Where( $table, $clause, $where );
		
		$query	=	'SELECT * FROM '. $this->_tables[$table]['table']
                .' WHERE ' . implode( ' AND ', $where );

        if( !empty( $limit ) ) {
            // add order by
            if( isset( $this->_tables[$table]['order'] ) ) {
                $query  .=  ' ORDER BY ' . $this->_tables[$table]['table'] . '.'. $this->_tables[$table]['order'];
                if( isset( $this->_tables[$table]['orderdir'] ) ) {
                    $query  .=  ' ' . $this->_tables[$table]['orderdir'];
                }
            }
            $query  .=  ' LIMIT ' . $limit;
        }
		
		$this->_addDebugMessage( $query, 'Get entry SQL' );
		$result	=	$this->_dc->query( $query );
		
		// check result
		if( DB::isError( $result ) ) {
			return patErrorManager::raiseError( 
						'wbDatasource:5',
						'Get entry failed',
						'Query: ' . $query 
					 );
		}
		
		// expect a single row
		if( ( $rows = $result->numRows() ) != 1 ) {
			return $rows;
		}

		$entry	=	$result->fetchRow( DB_FETCHMODE_ASSOC );
		if( $this->_useCallback( $table, 'getentry' ) ) {
			$result	=	$this->_callback->callForGetentry( $table, $entry, $entry[$primary] );
			if( patErrorManager::isError( $result ) ) {
				return $result;
			}
		}
		
		return $entry;
    }
   /**
	* recieve multiple rows from a table
	*
	* @access public
	* @param string $table	named table in db
	* @param int $foreign if foreign key
	* @param array $clause additional clause
	* @return array $entries associative array containing entries from db
	*/
    function getEntries( $table, $foreign = null, $clause = array(), $offset = null )
    {
		$primary	=	$this->_tables[$table]['primary'];
		$where		=	array();
		$group		=	null;
		
		$query		=	'SELECT * FROM ';
		
		if( $foreign !== null && isset( $this->_tables[$table]['foreign'] ) )
		{
			$fKey	=	$this->_tables[ $this->_tables[$table]['foreign'] ]['primary'];
			array_push( $where,  $fKey . '=' . $this->_dc->quote( $foreign ) );
		}
		else if( isset( $this->_tables[$table]['foreign'] ) )
		{
			$lTable	=	$this->_tables[$table]['table'];
			$rTable	=	$this->_tables[ $this->_tables[$table]['foreign'] ]['table'];
			$query	.=	$rTable . ', ';
			$fKey	=	$this->_tables[ $this->_tables[$table]['foreign'] ]['primary'];
			array_push( $where,  $lTable . '.' . $fKey . '=' . $rTable . '.' . $fKey );
			$group	=	$lTable . '.' . $primary;
		}

        $query  .=  $this->_tables[$table]['table'];
        
		// skip entries marked as deleted.	
		if( isset( $this->_tables[$table]['delete'] ) )
		{
			list( $key, $value )	=	explode( '=', $this->_tables[$table]['delete'] );
			array_push( $clause, array( 'relation' => 'not_in_set', 'field' => $key, 'value' => $value ) );
		}
		
		$this->_clause2Where( $table, $clause, $where );
		
		if( !empty( $where ) )
		{
			$query .=	' WHERE ' . implode( ' AND ', $where );
		}
		
		if( $group )
		{
			$query .=	' GROUP BY ' . $group;
		}
		
		// add order by
		if( isset( $this->_tables[$table]['order'] ) )
		{
			$query	.=	' ORDER BY ' . $this->_tables[$table]['table'] . '.'. $this->_tables[$table]['order'];
			if( isset( $this->_tables[$table]['orderdir'] ) )
			{
				$query	.=	' ' . $this->_tables[$table]['orderdir'];
			}
		}
		
		// add limit and offset
		$limit	=	-1;
		if( isset( $this->_tables[$table]['limit'] ) )
		{
			$limit	=	$this->_tables[$table]['limit'];
		}
		
		if( $limit > -1 || $offset !== null )
		{
			if( $offset === null )
			{
				$offset = 0;
			}
			$query	.=	' LIMIT ' . $offset . ',' . $limit;
		}
		
		// get entries from db
		$this->_addDebugMessage( $query, 'Get entries SQL' );
		$entries	=	$this->_dc->getAll( $query, array(), DB_FETCHMODE_ASSOC );
		if( DB::isError( $entries ) )
		{
			return patErrorManager::raiseError( 
						'wbDatasource:4',
						'Get entries failed!',
						'Query: ' . $query 
					 );
		}
		
		$class	=	get_class( $this->_callback );
		
		// callback? 
		if( $this->_useCallback( $table, 'getentries' ) )
		{
			for( $i = 0; $i < count( $entries ); ++$i )
			{
				$result = $this->_callback->callForGetentries( $table, $entries[$i], $entries[$i][$primary] );
				if( patErrorManager::isError( $result ) )
				{
					return $result;
				}
			}
		}
		
	    return $entries;
    }

   /**
	* submitt a complex query and get join
	* 
 	* @access public
	* @param array $tables list of tables, the first table must be the most significant table
	* @param array $selects complex list for selects; 
	* @param array $clause complex clause
	* @param array $order 'order' = fieldname, 'orderdir' = asc|desc, 'limit' =  number
	* @return boolean $result true on success
	*/
    function getJoin( $tables, $selects = null, $clause = array(), $options = null ) {
		if( empty( $selects ) ) {
			$select	=	$this->_tables[$tables[0]]['table'] . '.*';
		}
		else {
			$select	=	array();
			foreach( $selects as $tab => $value ) {
			
				// select all or none of a table
				if( !is_array( $value ) ) {
					switch( $value ) {
						case 'all':
							$sel	=	$this->_tables[$tab]['table'] . '.*';
							array_push( $select, $sel );
							break;
							
						case 'none';
							break;
					}
					continue;
				}
			
				// more specific select
				for( $i = 0; $i < count( $value ); ++$i ) {
					if( isset( $value[$i]['direct'] ) ) {
						$sel	=	$value[$i]['direct'];
					}
					else
					{
						if( isset( $value[$i]['function'] ) ) {
							$sel	=	$value[$i]['function'] . '( '. $this->_tables[$tab]['table'] . '.' . $value[$i]['field'] .' )';
						}
						else {
							$sel	=	$this->_tables[$tab]['table'] . '.' . $value[$i]['field'];
						}
					}
				
					if( isset( $value[$i]['as'] ) ) {
						$sel .=	' AS ' . $value[$i]['as'];
					}
						
					array_push( $select, $sel );
				}
			}
			$select	=	implode( ', ', $select );
		}
		
		$allTables	=	array();
		foreach( $tables as $tab ) {
			array_push( $allTables, $this->_tables[$tab]['table'] );
		}
		$query		=	'SELECT ' . $select . ' FROM ' . implode( ', ', $allTables );
		$firstTable	=	array_shift( $allTables );
		
		// group by primary key of first table
		$group		=	$firstTable . '.' . $this->_tables[$tables[0]]['primary'];

		// build where clause
		$where		=	array();
		
		// add foreign keys to clause
		foreach( $tables as $table ) {
			if( isset( $this->_tables[$table]['foreign'] ) && in_array( $this->_tables[$table]['foreign'], $tables ) ) {
				// check direction of foreign keys
				if( $this->_tables[$table]['foreign'] == $tables[0] ) {
					$foreign	=	$this->_tables[$tables[0]]['primary'];
				}
				else {
					$foreign	=	$this->_tables[ $this->_tables[$table]['foreign'] ]['primary'];
				}
				array_push( $where, 
									$firstTable . '.' . $foreign 
									. '=' 
									. $this->_tables[$this->_tables[$table]['foreign']]['table'] . '.' . $foreign 
							);
			}
		}
		
		$this->_clause2Where( $tables[0], $clause, $where );
		$query	.=	' WHERE ' . implode( ' AND ', $where ) . ' GROUP BY ' . $group; 
		
		// common options
		if( $options === null ) {
			// load options from first table
			$options	=	$this->_tables[$tables[0]];
		}
		
		// add order by
		if( isset( $options['order'] ) ) {
			$query	.=	' ORDER BY ' . $options['order'];
			if( isset( $options['orderdir'] ) ) {
				$query	.=	' ' . $options['orderdir'];
			}
		}
		
		// add limit
		if( isset( $options['limit'] ) ) {
			$offset	=	'';
			if( isset( $options['offset'] ) ) {
				$offset	=	$options['offset'] . ', ';
			}
			
			$query	.=	' LIMIT ' . $offset .  $options['limit'];
		}
		
		// get entries from db
		$this->_addDebugMessage( $query, 'Get join SQL' );
		$entries	=	$this->_dc->getAll( $query, array(), DB_FETCHMODE_ASSOC );
		if( DB::isError( $entries ) ) {
			return patErrorManager::raiseWarning(	
											'wbDatasource:5',
											'Join failed!',
											'Query: ' . $query 
										);
		}
		
		// callback? 
		if( $this->_useCallback( $tables[0], 'getjoin' ) ) {
			for( $i = 0; $i < count( $entries ); ++$i ) {
				$result = $this->_callback->callForGetjoin( $tables[0], $entries[$i] );
				if( patErrorManager::isError( $result ) ) {
					return $result;
				}
			}
		}
		return $entries;
    }

   /**
	* helper function tranlates clause-array to where array
	*
	* @access private
	* @return boolean $result true on success
	*/
    function _clause2Where( $table, $clause, &$where ) {
		if( !is_array( $clause ) ) {
			return true;
		}
		
		// manage clause
		for( $i = 0; $i < count( $clause ); ++$i ) {
			// strange wrong argument!
			if( !isset( $clause[$i] ) ) {
				return patErrorManager::raiseError(
											'wbDatasource:2',
											'Clause to where converter failed',
											'Clause has wrong format! - numberd array expected!'
										);
			}
			
			if( !isset( $clause[$i]['table'] ) ) {
				$clause[$i]['table'] = $table;
			}
			
			$type	=	'simple';
		    if( isset( $clause[$i]['type'] ) ) {
				$type	=	$clause[$i]['type'];
			}
			
			switch( strtolower( $type ) ) {
				case	'simple';
					$whereClause 	=	$this->_getWhereClause( $clause[$i] );
					break;
					
				case	'complex':
					$myWhere	=	array();
					$this->_clause2Where( $table, $clause[$i]['clause'], $myWhere );
					$whereClause	=	'( ' . implode( ' ' . $clause[$i]['bond'] . ' ', $myWhere ) . ' )';
					break;
			}
			
			array_push( $where, $whereClause );
		}
		
		return true;
	}
		
   /**
	* helper function tranlates clause-array to where array
	*
	* @access private
	* @param array $clause clause to be translated
	* @return boolean $result true on success
	*/
    function _getWhereClause( $clause )
	{
		if( !isset( $clause['valuetype'] ) ) {
			$clause['valuetype']	=	'_default_';
		}
		
		switch( strtolower( $clause['valuetype'] ) ) {
			case 'function':
				$value	=	$clause['value'];
				break;
				
			case 'foreign':
				$foreign	=	$this->_tables[$clause['foreign']]['table'];
				$value	=	$foreign . '.' . $clause['value'];
				break;
			
			default:
				$value	=	$this->_dc->quote( $clause['value'] );
				break;
		}
	
		if( !isset( $clause['relation'] ) ) {
			$clause['relation']	=	'_default_';
		}

		// select relation
		switch( strtolower( $clause['relation'] ) )  {
			case	'like':
				$rel	=	"%s LIKE '%%%s%%'";
				$value	=	substr( $value, 1, -1 );
				break;
				
			case	'not_in_set':
				$rel	=	'NOT FIND_IN_SET( %2$s, %1$s )';
				break;
				
			case	'in_set':
				$rel	=	'FIND_IN_SET( %2$s, %1$s )';
				break;
				
			case	'<':
				$rel	=	'%s<%s';
				break;
				
			case	'<=':
				$rel	=	'%s<=%s';
				break;
				
			case	'>':
				$rel	=	'%s>%s';
				break;
				
			case	'>=':
				$rel	=	'%s>=%s';
				break;
				
			case	'<>':
			case	'not':
				$rel	=	'%s<>%s';
				break;
				
			default:
				$rel	=	'%s=%s';
				break;	
		}
		return sprintf( $rel, $this->_tables[$clause['table']]['table'] . '.' . $clause['field'], $value );
    }
	
   /**
	* interface to recieve field-list
	*
	* @access public
	* @param string $table name of table
	* @return array $fields list of fields
	* @see _recieveFieldList()
	*/
    function getFieldList( $table )
    {
		$this->_recieveFieldList( $table );
		return $this->_tables[$table]['fields'];
    }

   /**
	* calculate offset for pager
	*
	* @access public
	* @param string $table named table
	* @param string $goto named goto - like "next, prev, current" or a numeric value
    * @param int $foreign
	* @param array $clause 
	* @return int $offset the current offset
	*/
    function getPager( $table, $goto, $foreign = null, $clause = null )
    {
		// make sure that the offset will be only calculated once per request
		if( $this->_pager !== null ) {
			return $this->_pager;
		}
		
		// need some information about table and "page"
		$total	=	$this->count( $table, $foreign, $clause );
		
		$limit	=	-1;
		if( isset( $this->_tables[$table]['limit'] ) ) {
		    $limit	=	$this->_tables[$table]['limit'];
		}
		
		$pages	=	1;
		if( $limit > 0 ) {
            $pages	=	ceil( $total / $limit );
		}
		
		$pager				=	array();
		$pager['next']		=	0;
		$pager['prev']		=	0;
		$pager['offset']	=	0; // page offset
        // $pager['queryoffset'] =   0; // read to use in query offset
		$pager['current']	=	1;
		$pager['limit']		=	$limit;
		$pager['pages']		=	$pages;
		$pager['total']		=	$total;
		
		// no limit, no pager
		if( !isset( $this->_tables[$table]['limit'] ) || $this->_tables[$table]['limit'] == 0 ) {
			return $pager;
		}
		
		// keep offset in session!
		$offset	=	$this->_sess->get( 'wbDatasource_' . $table . '_offset' );
		if( $offset === null ) {
			$offset	=	0;
		}

		// select extimated next offset		
		switch( $goto ) {
            case 'last':
                $offset =   $pages;
                break;
                
            case 'first':
			case 'current':
				$offset	=	0;
				break;
				
			case 'prev':
				--$offset;
				break;
				
			case 'next':
				++$offset;
				break;
				
			default:
				if( is_numeric( $goto ) ) {
					$offset	=	$goto;
				}
				break;
		}
		
		// build pager
		if( $offset < 0 ) {
			$offset = 0;
		}
		
		if( ( $pages - 1 ) < $offset ) {
			$offset = $pages - 1;
		}
		
		if( ( $pages - 1 ) > $offset ) {
			$pager['next']	=	1;
		}
		
		if( $offset > 0 ) {
			$pager['prev']	=	1;
		}
		
		$this->_sess->set( 'wbDatasource_' . $table . '_offset', $offset );
		$pager['offset']	=	$offset;
		$pager['current']	=	$offset + 1;
		
		$this->_pager		=	$pager;
        return $pager;
    }
	
   /**
	* save list of table fiels into member-variable
	*
	* @access private
	* @param string $table name of table
	* @return boolean $result true on success
	* @todo	check whether 'DESC table' works in all cases
	*/
    function _recieveFieldList( $table )
    {
		// this has to be done only once per table
		if( isset( $this->_tables[$table]['fields'] ) && !empty( $this->_tables[$table]['fields'] ) ) {
			return true;
		}
	
		$query	=	'DESC ' . $this->_tables[$table]['table'];
		$entry	=	$this->_dc->getCol( $query );
		if( DB::isError( $entry ) ) {
				return patErrorManager::raiseError(
											'wbDatasource:3',
											'Could not get list of fields',
											'DB-Query failed: '. $query .'!'
										);
		}
	
		$this->_tables[$table]['fields']	=	$entry;
		
        return true;
    }

   /**
	* check whether callback should be used
	*
	* @access private
	* @param string $table name of table
	* @param string $name callback name
	* @return boolean $result true if callback exists
	*/
    function _useCallback( $table, $name )
    {
		if( !isset( $this->_tables[$table]['callback'] ) ) {
			return false;
		}
		
		$calldefs	=	explode( ',', $this->_tables[$table]['callback'] );
		if( in_array( $name, $calldefs ) ) {
			return true;
		}
		
		return false;
	}
	
   /**
    * add debug message to debugger 
	*
	*
	* @access private
	* @param string $text
	* @param string $itle
	* @return boolean $result true on success
	*/
    function _addDebugMessage( $text, $title = null ) {
	    if( !$this->_debug ) {
			return true;
		}
		
		return wbDebugger::addMsg( 'wbDatasource', $text, $title );
    }
}
?>