<?php
require_once("tools.php");

/*! manager of data request
**/
class DataRequestConfig{
	private $filters;	//!< array of filtering rules
	private $relation=false;	//!< ID or other element used for linking hierarchy
	private $sort_by;	//!< sorting field 
	private $start;	//!< start of requested data
	private $count;	//!< length of requested data

    private $user;
    private $version;
	
	//for render_sql
	private $source;	//!< souce table or another source destination
	private $fieldset;	//!< set of data, which need to be retrieved from source
	
	/*! constructor

		@param proto 
			DataRequestConfig object, optional, if provided then new request object will copy all properties from provided one
	*/
	public function __construct($proto=false){
		if ($proto)
			$this->copy($proto);
		else{
			$start=0;
			$this->filters=array();
			$this->sort_by=array();
		}
	}
	
	/*! copy parameters of source object into self
		
		@param proto 
			source object
	*/
	public function copy($proto){
		$this->filters	=$proto->get_filters();
		$this->sort_by	=$proto->get_sort_by();
		$this->count	=$proto->get_count();
		$this->start	=$proto->get_start();
		$this->source	=$proto->get_source();
		$this->fieldset	=$proto->get_fieldset();
		$this->relation		=$proto->get_relation();
        $this->user = $proto->user;
        $this->version = $proto->version;
	}
	
	/*! convert self to string ( for logs )
		@return 
			self as plain string,
	*/
	public function __toString(){
		$str="Source:{$this->source}\nFieldset:{$this->fieldset}\nWhere:";
		for ($i=0; $i < sizeof($this->filters); $i++)
			$str.=$this->filters[$i]["name"]." ".$this->filters[$i]["operation"]." ".$this->filters[$i]["value"].";";
		$str.="\nStart:{$this->start}\nCount:{$this->count}\n";
		for ($i=0; $i < sizeof($this->sort_by); $i++)
			$str.=$this->sort_by[$i]["name"]."=".$this->sort_by[$i]["direction"].";";
		$str.="\nRelation:{$this->relation}";
		return $str;
	}

	/*! returns set of filtering rules
		@return 
			set of filtering rules
	*/
	public function get_filters(){
		return $this->filters;
	}
	public function &get_filters_ref(){
		return $this->filters;
	}
	public function set_filters($data){
		$this->filters=$data;
	}


    public function get_user(){
        return $this->user;
    }
    public function set_user($user){
        $this->user = $user;
    }
    public function get_version(){
        return $this->version;
    }
    public function set_version($version){
        $this->version = $version;
    }

	/*! returns list of used fields
		@return 
			list of used fields
	*/
	public function get_fieldset(){
		return $this->fieldset;
	}
	/*! returns name of source table 
		@return 
			name of source table 
	*/
	public function get_source(){
		return $this->source;
	}
	/*! returns set of sorting rules
		@return 
			set of sorting rules
	*/
	public function get_sort_by(){
		return $this->sort_by;
	}
	public function &get_sort_by_ref(){
		return $this->sort_by;
	}
	public function set_sort_by($data){
		$this->sort_by=$data;
	}
	
	/*! returns start index 
		@return 
			start index
	*/
	public function get_start(){
		return $this->start;
	}
	/*! returns count of requested records
		@return 
			count of requested records
	*/
	public function get_count(){
		return $this->count;
	}
	/*! returns name of relation id
		@return 
			relation id name
	*/
	public function get_relation(){
		return $this->relation;
	}
	
	/*! sets sorting rule
		
		@param field 
			name of column
		@param order
			direction of sorting
	*/
	public function set_sort($field,$order=false){
		if (!$field && !$order)
			$this->sort_by=array();
		else{
			$order=strtolower($order)=="asc"?"ASC":"DESC";
			$this->sort_by[]=array("name"=>$field,"direction" => $order);
		}
	}
	/*! sets filtering rule
		
		@param field 
			name of column
		@param value
			value for filtering
		@param operation
			operation for filtering, optional , LIKE by default
	*/
	public function set_filter($field,$value,$operation=false){
		array_push($this->filters,array("name"=>$field,"value"=>$value,"operation"=>$operation));
	}
	
	/*! sets list of used fields
		
		@param value
			list of used fields
	*/
	public function set_fieldset($value){
		$this->fieldset=$value;
	}
	/*! sets name of source table
		
		@param value 
			name of source table
	*/
	public function set_source($value){
		$this->source=trim($value);
		if (!$this->source) throw new Exception("Source of data can't be empty");
	}
	/*! sets data limits
		
		@param start
			start index
		@param count
			requested count of data
	*/
	public function set_limit($start,$count){
		$this->start=$start;
		$this->count=$count;
	}
	/*! sets name of relation id
		
		@param value 
			name of relation id field
	*/
	public function set_relation($value){
		$this->relation=$value;
	}
	/*! parse incoming sql, to fill other properties
		
		@param sql
			incoming sql string
	*/
	public function parse_sql($sql){
		$sql= preg_replace("/[ \n\t]+limit[\n ,0-9]/i","",$sql);
		
		$data = preg_split("/[ \n\t]+\\_from\\_/i",$sql,2);
		if (count($data)!=2)
			$data = preg_split("/[ \n\t]+from/i",$sql,2);
		$this->fieldset = preg_replace("/^[\s]*select/i","",$data[0],1);
		
	  	$table_data = preg_split("/[ \n\t]+where/i",$data[1],2);
	  	if (sizeof($table_data)>1){ //where construction exists
	  		$this->set_source($table_data[0]);
  			$where_data = preg_split("/[ \n\t]+order[ ]+by/i",$table_data[1],2);
  			$this->filters[]=$where_data[0];
  			if (sizeof($where_data)==1) return; //end of line detected
  			$data=$where_data[1];
  		} else {
  			$table_data = preg_split("/[ \n\t]+order[ ]+by/i",$table_data[0],2);	
  			$this->set_source($table_data[0]);
  			if (sizeof($table_data)==1) return; //end of line detected
  			$data=$table_data[1];
  		}
	  	
      	if (trim($data)){ //order by construction exists
			$s_data = preg_split("/\\,/",trim($data));
			for ($i=0; $i < count($s_data); $i++) { 
				$data=preg_split("/[ ]+/",trim($s_data[$i]),2);
				$this->set_sort($data[0],$data[1]);
			}
			
		}
	}
}
	
/*! manager of data configuration
**/
class DataConfig{
	public $id;////!< name of ID field
	public $relation_id;//!< name or relation ID field
	public $text;//!< array of text fields
	public $data;//!< array of all known fields , fields which exists only in this collection will not be included in dataprocessor's operations
	
	
	/*! converts self to the string, for logging purposes
	**/
	public function __toString(){
		$str="ID:{$this->id['db_name']}(ID:{$this->id['name']})\n";
		$str.="Relation ID:{$this->relation_id['db_name']}({$this->relation_id['name']})\n";
		$str.="Data:";
		for ($i=0; $i<sizeof($this->text); $i++)
			$str.="{$this->text[$i]['db_name']}({$this->text[$i]['name']}),";
			
		$str.="\nExtra:";
		for ($i=0; $i<sizeof($this->data); $i++)
			$str.="{$this->data[$i]['db_name']}({$this->data[$i]['name']}),";
			
		return $str;
	}
	
	/*! removes un-used fields from configuration
		@param name 
			name of field , which need to be preserved
	*/
	public function minimize($name){
		for ($i=0; $i < sizeof($this->text); $i++){
			if ($this->text[$i]["db_name"]==$name || $this->text[$i]["name"]==$name){
				$this->text[$i]["name"]="value";
				$this->data=array($this->text[$i]);
				$this->text=array($this->text[$i]);
				return;
			}
		}
		throw new Exception("Incorrect dataset minimization, master field not found.");
	}
	
	public function limit_fields($data){
		if (isset($this->full_field_list))
			$this->restore_fields();
		$this->full_field_list = $this->text;
		$this->text = array();
			
		for ($i=0; $i < sizeof($this->full_field_list); $i++) { 
			if (array_key_exists($this->full_field_list[$i]["name"],$data))
				$this->text[] = $this->full_field_list[$i];
		}
	}
	
	public function restore_fields(){
		if (isset($this->full_field_list))
			$this->text = $this->full_field_list;
	}
	
	/*! initialize inner state by parsing configuration parameters

		@param id 
			name of id field
		@param fields
			name of data field(s)
		@param extra
			name of extra field(s)
		@param relation
			name of relation field
			
	*/
	public function init($id,$fields,$extra,$relation){
		$this->id	= $this->parse($id,false);
		$this->text = $this->parse($fields,true);
		$this->data	= array_merge($this->text,$this->parse($extra,true));
		$this->relation_id = $this->parse($relation,false);
	}
	
	/*! parse configuration string
		
		@param key 
			key string from configuration
		@param mode
			multi names flag
		@return 
			parsed field name object
	*/
	private function parse($key,$mode){
		if ($mode){
			if (!$key) return array();
			$key=explode(",",$key);
			for ($i=0; $i < sizeof($key); $i++)
				$key[$i]=$this->parse($key[$i],false);
			return $key;
		}
		$key=explode("(",$key);
		$data=array("db_name"=>trim($key[0]), "name"=>trim($key[0]));
		if (sizeof($key)>1)
			$data["name"]=substr(trim($key[1]),0,-1);
		return $data;		
	}
	
	/*! constructor
		init public collectons
		@param proto
			DataConfig object used as prototype for new one, optional
	*/
	public function __construct($proto=false){
		if ($proto!==false)
			$this->copy($proto);
		else {
			$this->text=array();
			$this->data=array();
			$this->id=array("name"=>"dhx_auto_id", "db_name"=>"dhx_auto_id");
			$this->relation_id=array("name"=>"", "db_name"=>"");
		}
	}
	
	/*! copy properties from source object
		
		@param proto 
			source object
	*/
	public function copy($proto){
		$this->id = $proto->id;
		$this->relation_id = $proto->relation_id;
		$this->text = $proto->text;
		$this->data = $proto->data;			
	}

	/*! returns list of data fields (db_names)
		@return 
			list of data fields ( ready to be used in SQL query )
	*/
	public function db_names_list($db){
		$out=array();
		if ($this->id["db_name"])
			array_push($out,$db->escape_name($this->id["db_name"]));
		if ($this->relation_id["db_name"])
			array_push($out,$db->escape_name($this->relation_id["db_name"]));
		
		for ($i=0; $i < sizeof($this->data); $i++){
			if ($this->data[$i]["db_name"]!=$this->data[$i]["name"])
				$out[]=$db->escape_name($this->data[$i]["db_name"])." as ".$this->data[$i]["name"];
			else
				$out[]=$db->escape_name($this->data[$i]["db_name"]);
		}
		
		return $out;
	}
	
	/*! add field to dataset config ($text collection)
	
		added field will be used in all auto-generated queries
		@param name 
			name of field
		@param aliase
			aliase of field, optional
	*/	
	public function add_field($name,$aliase=false){
		if ($aliase===false) $aliase=$name;
		
		//adding to list of data-active fields
		if ($this->id["db_name"]==$name || $this->relation_id["db_name"] == $name){
			LogMaster::log("Field name already used as ID, be sure that it is really necessary.");
		}
		if ($this->is_field($name,$this->text)!=-1)
			throw new Exception('Data field already registered: '.$name);
		array_push($this->text,array("db_name"=>$name,"name"=>$aliase));
		
		//adding to list of all fields as well
		if ($this->is_field($name,$this->data)==-1)
			array_push($this->data,array("db_name"=>$name,"name"=>$aliase));
		
	}
	
	/*! remove field from dataset config ($text collection)

		removed field will be excluded from all auto-generated queries
		@param name 
			name of field, or aliase of field
	*/
	public function remove_field($name){
		$ind = $this->is_field($name);
		if ($ind==-1) throw new Exception('There was no such data field registered as: '.$name);
		array_splice($this->text,$ind,1);
		//we not deleting field from $data collection, so it will not be included in data operation, but its data still available
	}
	
	/*! check if field is a part of dataset

		@param name 
			name of field
		@param collection
			collection, against which check will be done, $text collection by default
		@return 
			returns true if field already a part of dataset, otherwise returns true
	*/
	private function is_field($name,$collection = false){
		if (!$collection)
			$collection=$this->text;
			
		for ($i=0; $i<sizeof($collection); $i++)
			if ($collection[$i]["name"] == $name || $collection[$i]["db_name"] == $name)	return $i;
		return -1;
	}
	
	
}

/*! Base abstraction class, used for data operations
	Class abstract access to data, it is a base class to all DB wrappers
**/
abstract class DataWrapper{
	protected $connection;
	protected $config;//!< DataConfig instance
	/*! constructor
		@param connection
			DB connection
		@param config 
			DataConfig instance
	*/
	public function __construct($connection,$config){
		$this->config=$config;
		$this->connection=$connection;
	}
	
	/*! insert record in storage
		
		@param data 
			DataAction object
		@param source
			DataRequestConfig object
	*/
	abstract function insert($data,$source);
	
	/*! delete record from storage
		
		@param data 
			DataAction object
		@param source
			DataRequestConfig object
	*/
	abstract function delete($data,$source);
	
	/*! update record in storage
		
		@param data 
			DataAction object
		@param source
			DataRequestConfig object
	*/
	abstract function update($data,$source);
	
	/*! select record from storage
		
		@param source
			DataRequestConfig object
	*/
	abstract function select($source);
	
	/*! get size of storage
		
		@param source
			DataRequestConfig object
	*/
	abstract function get_size($source);
	
	/*! get all variations of field in storage
		
		@param name
			name of field
		@param source
			DataRequestConfig object
	*/
	abstract function get_variants($name,$source);
	
	/*! checks if there is a custom sql string for specified db operation
		
		@param  name
			name of DB operation
		@param  data
			hash of data
		@return 
			sql string
	*/
	public function get_sql($name,$data){
		return ""; //custom sql not supported by default
	}
	
	/*! begins DB transaction
	*/
	public function begin_transaction(){
		throw new Exception("Data wrapper not supports transactions.");
	}
	/*! commits DB transaction
	*/
	public function commit_transaction(){
		throw new Exception("Data wrapper not supports transactions.");
	}
	/*! rollbacks DB transaction
	*/
	public function rollback_transaction(){
		throw new Exception("Data wrapper not supports transactions.");
	}	
}

/*! Common database abstraction class
	Class provides base set of methods to access and change data in DB, class used as a base for DB-specific wrappers
**/
abstract class DBDataWrapper extends DataWrapper{
	private $transaction = false; //!< type of transaction
	private $sequence=false;//!< sequence name
	private $sqls = array();//!< predefined sql actions
	
	
	/*! assign named sql query
		@param name 
			name of sql query
		@param data
			sql query text
	*/
	public function attach($name,$data){
		$name=strtolower($name);
		$this->sqls[$name]=$data;
	}
	/*! replace vars in sql string with actual values
		
		@param matches 
			array of field name matches
		@return 
			value for the var name
	*/
	public function get_sql_callback($matches){
		return $this->escape($this->temp->get_value($matches[1]));
	}
	public function get_sql($name,$data){
		$name=strtolower($name);
		if (!array_key_exists($name,$this->sqls)) return "";
		
		
		$str = $this->sqls[$name];
		$this->temp = $data; //dirty
		$str = preg_replace_callback('|\{([^}]+)\}|',array($this,"get_sql_callback"),$str);
		unset ($this->temp); //dirty
		return $str;
	}

	public function insert($data,$source){
		$sql=$this->insert_query($data,$source);
		$this->query($sql);
		$data->success($this->get_new_id());
	}
	public function delete($data,$source){
		$sql=$this->delete_query($data,$source);
		$this->query($sql);
		$data->success();
	}
	public function update($data,$source){
		$sql=$this->update_query($data,$source);
		$this->query($sql);
		$data->success();
	}
	public function select($source){
		$select=$source->get_fieldset();
		if (!$select){
			$select=$this->config->db_names_list($this);
			$select = implode(",",$select);
		}
		
		$where=$this->build_where($source->get_filters(),$source->get_relation());
		$sort=$this->build_order($source->get_sort_by());
			
		return $this->query($this->select_query($select,$source->get_source(),$where,$sort,$source->get_start(),$source->get_count()));
	}	
	public function get_size($source){
		$count = new DataRequestConfig($source);
		
		$count->set_fieldset("COUNT(*) as DHX_COUNT ");
		$count->set_sort(null);
		$count->set_limit(0,0);
		
		$res=$this->select($count);
		$data=$this->get_next($res);
		if (array_key_exists("DHX_COUNT",$data)) return $data["DHX_COUNT"];
		else return $data["dhx_count"]; //postgresql
	}
	public function get_variants($name,$source){
		$count = new DataRequestConfig($source);
		$count->set_fieldset("DISTINCT ".$this->escape_name($name)." as value");
		$count->set_sort(null);
		$count->set_limit(0,0);
		
		return $this->select($count);
	}
	
	public function sequence($sec){
		$this->sequence=$sec;
	}
		
	
	/*! create an sql string for filtering rules
		
		@param rules 
			set of filtering rules
		@param relation
			name of relation id field
		@return 
			sql string with filtering rules
	*/
	protected function build_where($rules,$relation=false){
		$sql=array();
		for ($i=0; $i < sizeof($rules); $i++)
			if (is_string($rules[$i]))
				array_push($sql,$rules[$i]);
			else
				if ($rules[$i]["value"]!=""){
					if (!$rules[$i]["operation"])
						array_push($sql,$this->escape_name($rules[$i]["name"])." LIKE '%".$this->escape($rules[$i]["value"])."%'");
					else
						array_push($sql,$this->escape_name($rules[$i]["name"])." ".$rules[$i]["operation"]." '".$this->escape($rules[$i]["value"])."'");
				}
		if ($relation!==false)
			array_push($sql,$this->escape_name($this->config->relation_id["db_name"])." = '".$this->escape($relation)."'");
		return implode(" AND ",$sql);
	}	
	/*! convert sorting rules to sql string
		
		@param by 
			set of sorting rules
		@return 
			sql string for set of sorting rules
	*/
	protected function build_order($by){
		if (!sizeof($by)) return "";
		$out = array();
		for ($i=0; $i < sizeof($by); $i++)
			if ($by[$i]["name"])
				$out[]=$this->escape_name($by[$i]["name"])." ".$by[$i]["direction"];
		return implode(",",$out);
	}	
	
	/*! generates sql code for select operation
		
		@param select 
			list of fields in select
		@param from 
			table name
		@param where
			list of filtering rules
		@param sort
			list of sorting rules
		@param start
			start index of fetching
		@param count 
			count of records to fetch
		@return 
			sql string for select operation
	*/
	protected function select_query($select,$from,$where,$sort,$start,$count){
		$sql="SELECT ".$select." FROM ".$from;
		if ($where) $sql.=" WHERE ".$where;
		if ($sort) $sql.=" ORDER BY ".$sort;
		if ($start || $count) $sql.=" LIMIT ".$start.",".$count;
		return $sql;
	}
	/*! generates update sql
		
		@param data
			DataAction object
		@param request
			DataRequestConfig object
		@return 
			sql string, which updates record with provided data
	*/
	protected function update_query($data,$request){
		$sql="UPDATE ".$request->get_source()." SET ";
		$temp=array();
		for ($i=0; $i < sizeof($this->config->text); $i++) { 
			$step=$this->config->text[$i];
			
			if ($data->get_value($step["name"])===Null)
				$step_value ="Null";
			else
				$step_value = "'".$this->escape($data->get_value($step["name"]))."'";
			$temp[$i]= $this->escape_name($step["db_name"])."=". $step_value;
		}
		if ($relation = $this->config->relation_id["db_name"]){
			$temp[]= $this->escape_name($relation)."='".$this->escape($data->get_value($relation))."'";
		}
		$sql.=implode(",",$temp)." WHERE ".$this->escape_name($this->config->id["db_name"])."='".$this->escape($data->get_id())."'";
		
		//if we have limited set - set constraints
		$where=$this->build_where($request->get_filters(),$request->get_relation());
		if ($where) $sql.=" AND (".$where.")";
		
		return $sql;
	}
	
	/*! generates delete sql
		
		@param data
			DataAction object
		@param request
			DataRequestConfig object
		@return 
			sql string, which delete record 
	*/
	protected function delete_query($data,$request){
		$sql="DELETE FROM ".$request->get_source();
		$sql.=" WHERE ".$this->escape_name($this->config->id["db_name"])."='".$this->escape($data->get_id())."'";
		
		//if we have limited set - set constraints
		$where=$this->build_where($request->get_filters(),$request->get_relation());
		if ($where) $sql.=" AND (".$where.")";
		
		return $sql;
	}
	
	/*! generates insert sql
		
		@param data
			DataAction object
		@param request
			DataRequestConfig object
		@return 
			sql string, which inserts new record with provided data
	*/
	protected function insert_query($data,$request){
		$temp_n=array(); 
		$temp_v=array(); 
		foreach($this->config->text as $k => $v){
			$temp_n[$k]=$this->escape_name($v["db_name"]);
			if ($data->get_value($v["name"])===Null)
				$temp_v[$k]="Null";
			else
			$temp_v[$k]="'".$this->escape($data->get_value($v["name"]))."'";
		}
		if ($relation = $this->config->relation_id["db_name"]){
			$temp_n[]=$this->escape_name($relation);
			$temp_v[]="'".$this->escape($data->get_value($relation))."'";
		}
		if ($this->sequence){
			$temp_n[]=$this->escape_name($this->config->id["db_name"]);
			$temp_v[]=$this->sequence;
		}
		
		$sql="INSERT INTO ".$request->get_source()."(".implode(",",$temp_n).") VALUES (".implode(",",$temp_v).")";
		
		return $sql;
	}	
	
	/*! sets the transaction mode, used by dataprocessor
		
		@param mode 
			mode name
	*/
	public function set_transaction_mode($mode){
		if ($mode!="none" && $mode!="global" && $mode!="record") 
			throw new Exception("Unknown transaction mode");
		$this->transaction=$mode;
	}
	/*! returns true if global transaction mode was specified
		@return 
			true if global transaction mode was specified
	*/
	public function is_global_transaction(){
		return $this->transaction == "global";
	}
	/*! returns true if record transaction mode was specified
		@return 
			true if record transaction mode was specified
	*/	
	public function is_record_transaction(){
		return $this->transaction == "record";
	}
	
		
	public function begin_transaction(){
		$this->query("BEGIN");
	}
	public function commit_transaction(){
		$this->query("COMMIT");
	}
	public function rollback_transaction(){
		$this->query("ROLLBACK");
	}	
	
	/*! exec sql string
		
		@param sql 
			sql string
		@return 
			sql result set
	*/
	abstract protected function query($sql);
	/*! returns next record from result set
		
		@param res 
			sql result set
		@return 
			hash of data
	*/
	abstract public function get_next($res);
	/*! returns new id value, for newly inserted row
		@return 
			new id value, for newly inserted row
	*/
	abstract protected function get_new_id();
	/*! escape data to prevent sql injections
		@param data 
			unescaped data
		@return 
			escaped data
	*/
	abstract public function escape($data);			
	
	/*! escape field name to prevent sql reserved words conflict
		@param data 
			unescaped data
		@return 
			escaped data
	*/
	public function escape_name($data){
		return $data;
	}
	
	/*! get list of tables in the database
		
		@return 
			array of table names
	*/
	public function tables_list() {
		throw new Exception("Not implemented");
	}

	/*! returns list of fields for the table in question
		
		@param table 
			name of table in question
		@return 
			array of field names
	*/
	public function fields_list($table) {
		throw new Exception("Not implemented");
	}
	
}
/*! Implementation of DataWrapper for MySQL
**/
class MySQLDBDataWrapper extends DBDataWrapper{
	protected $last_result;
	public function query($sql){
		LogMaster::log($sql);
		$res=mysql_query($sql,$this->connection);
		if ($res===false) throw new Exception("MySQL operation failed\n".mysql_error($this->connection));
		$this->last_result = $res;
		return $res;
	}
	
	public function get_next($res){
		if (!$res)
			$res = $this->last_result;
			
		return mysql_fetch_assoc($res);
	}
	
	protected function get_new_id(){
		return mysql_insert_id($this->connection);
	}
	
	public function escape($data){
		return mysql_real_escape_string($data);
	}

	public function tables_list() {
		$result = mysql_query("SHOW TABLES");
		if ($result===false) throw new Exception("MySQL operation failed\n".mysql_error($this->connection));

		$tables = array();
		while ($table = mysql_fetch_array($result)) {
			$tables[] = $table[0];
		}
		return $tables;
	}

	public function fields_list($table) {
		$result = mysql_query("SHOW COLUMNS FROM `".$table."`");
		if ($result===false) throw new Exception("MySQL operation failed\n".mysql_error($this->connection));

		$fields = array();
        $id = "";
		while ($field = mysql_fetch_assoc($result)) {
			if ($field['Key'] == "PRI")
				$id = $field["Field"];
            else
			    $fields[] = $field["Field"];
		}
		return array("fields" => $fields, "key" => $id );
	}
	
	/*! escape field name to prevent sql reserved words conflict
		@param data 
			unescaped data
		@return 
			escaped data
	*/
	public function escape_name($data){
		if ((strpos($data,"`")!==false || is_int($data)) || (strpos($data,".")!==false))
			return $data;
		return '`'.$data.'`';
	}	
}
?>