abstract class Db_Abstract{
 
	// Force Db class to define these methods
	abstract protected function _prepare($query);
	abstract protected function _query($query);
	abstract protected function _result(); // resource will be stored inside the driver object
	abstract protected function _isConnected();
	abstract protected function _connect($params);
	abstract protected function _affectedRows(); // resource will be stored inside the driver object
	abstract protected function _driver($driver);
 
	/** =Public methods
	 * These functions will define the behavior of our Database class
	 **/
 
	/*
	* @function database
	* @description Select the database
	* @param String $db
	* @return Bool True|False
	*/
	public function database($db){
		return $this->driver->_selectDb($db);
	}
 
	/*
	* @function select
	* @description Select table rows
	* @param Array $fields
	* @param String $table
	* @param String $arguments (optional)
	* @return Array $rows
	*/
	public function select($fields,$table,$arguments=""){
		return $this->driver->select($fields,$table,$arguments);
	}
 
	/*
	* @function insert
	* @description Insert new row(s) into the table
	* @param Array $keys
	* @param Array mixed (String $values | Array $values)
	* @param String $table
	* @return Int $affectedRows
	*/
	public function insert($keys,$values,$table){
		return $this->driver->insert($keys,$values,$table);
	}
 
	/*
	* @function update
	* @description Update row(s) in the table
	* @param Array $keys
	* @param Array mixed (String $values | Array $values)
	* @param String $table
	* @param String $arguments (optional)
	* @return Int $affectedRows
	*/
	public function update($keys,$values,$table,$arguments=""){
		return $this->driver->update($keys,$values,$table,$arguments);
	}
 
	/*
	* @function delete
	* @description Delete a row from the table
	* @param String $key
	* @param String $value
	* @param String $table
	* @return Int $affectedRows
	*/
	public function delete($key,$value,$table){
		return $this->driver->delete($key,$value,$table);
	}
}

SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";
 
CREATE DATABASE `test` DEFAULT CHARACTER SET utf8 COLLATE utf8_unicode_ci;
USE `test`;
 
CREATE TABLE IF NOT EXISTS `test` (
  `key` VARCHAR(255) NOT NULL,
  `value` VARCHAR(255) NOT NULL,
  PRIMARY KEY  (`key`)
) ENGINE = MYISAM CHARACTER SET utf8 COLLATE utf8_unicode_ci;
 
INSERT INTO `test` (`key`, `value`) VALUES
('key1', 'value1'),
('key2', 'value2');

class Db extends Db_Abstract{
 
	var $driver;
 
	/*
	* @function __construct
	* @description Run on object creation
	* @param String $connection (input: 'driver://username:password@server:port/database')
	* @return void
	*/
	function __construct($connection=null){
		if(!defined('__DIR__')){
			define('__DIR__',dirname(__FILE__));
		}
		if(!empty($connection)){
			$connection = parse_url($connection);
			$this->_driver($connection['scheme']);
			$this->_connect($connection);
		}
	}
 
	/*
	* @function _escape
	* @description Emulate the behavior of mysql_real_escape_string() to prevent SQL Injection
	* @param String $query
	* @return String $query
	*/
	protected function _escape($query){
		$unsafe_tokens = array("\x00","\n","\r","\\","'",'"',"\x1a");
		$safe_tokens = array("\\\x00","\\\n","\\\r","\\\\","\\"."'","\\".'"',"\\\x1a");
		return str_replace($unsafe_tokens,$safe_tokens,$query);
	}
 
	/*
	* @function _prepare
	* @description Prepares the query before handing it over to the SQL client
	* @param String $query
	* @return String $query
	*/
	protected function _prepare($query){
		// In case the driver has it's own _prepare method
		if(method_exists($this->driver,'_prepare')){
			return $this->driver->_prepare($query);
		}
		return $this->_escape($query);
	}
 
	/*
	* @function _query
	* @description Runs an internal query request
	* @param String $query
	* @return Int $affectedRows
	*/
	protected function _query($query){
		$this->driver->query($query);
		return $this->_affectedRows();
	}
 
	/*
	* @function _result(void)
	* @description Fetch the result of a query
	* @return mixed $result
	*/
	protected function _result(){
		return $this->driver->_result();
	}
 
	/*
	* @function _isConnected(void)
	* @description Fetch the connection status
	* @return Bool True|False
	*/
	protected function _isConnected(){
		return (bool) is_object($this->driver)&&$this->driver->_isConnected();
	}
 
	/*
	* @function _connect
	* @description Connect to the database
	* @param Array $params (result of parse_url)
	* @return Bool True|False $isConnected
	*/
	protected function _connect($params){
		if(!empty($params['host'])&&!empty($params['user'])&&!empty($params['path'])){
			$host = $params['host'];
			$user = $params['user'];
			$pass = (!empty($params['pass'])) ? $params['pass'] : '';
			$port = (!empty($params['port'])) ? $params['port'] : 3306;
			$database = trim($params['path'],'/');
			$this->driver->_connect($host,$user,$pass,$port);
			$this->driver->_selectDb($database);
		}
		return $this->_isConnected();
	}
 
	/*
	* @function connect
	* @description Connect to the database
	* @param String $connection (input: 'driver://username:password@server:port/database')
	* @return Bool True|False $isConnected
	*/
	public function connect($connection){
		if(!$this->_isConnected()){
			$params = parse_url($connection);
			$this->_driver($params['scheme']);
			return $this->_connect($params);
		}
		return true;
	}
 
	/*
	* @function disconnect(void)
	* @description Disconnect from the database
	* @return void
	*/
	public function disconnect(){
		$this->driver->_disconnect();
	}
 
	/*
	* @function _affectedRows(void)
	* @description Fetch the number of rows affected by the last query
	* @return Int $affectedRows
	*/
	protected function _affectedRows(){
		return $this->driver->_affectedRows();
	}
 
	/*
	* @function _driver
	* @description Use the given driver
	* @param String $driver
	* @return void
	*/
	protected function _driver($driver){
		$driver_class = 'Db_Driver_'.ucfirst(strtolower($driver));
		$driver_file = __DIR__.'/drivers/'.strtolower($driver).'.php';
		if(!class_exists($driver_class)&&file_exists($driver_file)){
			require_once($driver_file);
		}
		if(!is_object($this->driver)||get_class($this->driver)!==$driver_class){
			$this->driver = new $driver_class;
		}
	}
 
}

interface Db_Driver_Interface {
 
	public function select($fields,$table,$arguments="");
	public function insert($keys,$values,$table);
	public function update($keys,$values,$table);
	public function delete($key,$value,$table);
 
	public function query($query);
	public function _result();
	public function _affectedRows();
 
	public function _isConnected();
	public function _connect($host,$user,$pass,$port);
	public function _selectDb($database);
	public function _disconnect();
 
}

class DB_Driver_Mysql implements Db_Driver_Interface {
 
	/*
	* @var $res
	* @description Used to store the connection and result resources
	*/
	var $res;
 
	/*
	* @function __construct(void)
	* @description Populate the resources array
	*/
	function __construct(){
		$this->res = array(
			'connection'	=> null,
			'result'		=> null
		);
	}
 
	/*
	* @function select
	* @description Select table rows
	* @param Array $fields
	* @param String $table
	* @param String $arguments (optional)
	* @return Array $rows
	*/
	public function select($fields,$table,$arguments=""){
		$query = 'SELECT `'.implode('`,`',$fields).'` FROM `'.$table.'`';
		$query .= (!empty($arguments)) ? ' '.$arguments : '';
		$this->query($query);
		return $this->_result();
	}
 
	/*
	* @function insert
	* @description Insert new row(s) into the table
	* @param Array $keys
	* @param Array mixed (String $values | Array $values)
	* @param String $table
	* @return Int $affectedRows
	*/
	public function insert($keys,$values,$table){
		$query = 'INSERT INTO `'.$table.'` (`'.implode('`, `',$keys).'`) VALUES ';
		if(isset($values[0])&&is_array($values[0])){ // There are multiple rows to be inserted
			$rows = array();
			foreach($values AS $row){
				$rows[] = '\''.implode('\', \'',$row).'\'';
			}
			$query .= '('.implode('), (',$rows).')';
		}
		else{
			$query .= '(\''.implode('\', \'',$values).'\')';
		}
		$query .= ';';
		$this->query($query);
		return $this->_affectedRows();
	}
 
	/*
	* @function update
	* @description Update row(s) in the table
	* @param Array $keys
	* @param Array mixed (String $values | Array $values)
	* @param String $table
	* @param String $arguments (optional)
	* @return Int $affectedRows
	*/
	public function update($keys,$values,$table,$arguments=""){
 
		$affectedRows = 0;
 
		if(!is_array($values[0])){ $values = array($values); } // Make it multi-dimensional
		for($i=0;$i<count($values);$i++){
			$vals = $values[$i];
			$query = 'UPDATE `'.$table.'` SET ';
			$updates = array();
			for($j=0;$j<count($keys);$j++){
				$val = (is_numeric($vals[$j])) ? $vals[$j] : "'".$this->_prepare($vals[$j])."'";
				$updates[] = '`'.$keys[$j].'` = '.$val;
			}
			$query .= implode(', ',$updates);
			$query .= (!empty($arguments)) ? ' '.$arguments : '';
			$this->query($query);
			$affectedRows += $this->_affectedRows();
		}
 
		return $affectedRows;
	}
 
	/*
	* @function delete
	* @description Delete a row from the table
	* @param String $key
	* @param String $value
	* @param String $table
	* @return Int $affectedRows
	*/
	public function delete($key,$value,$table){
		$value = (is_numeric($value)) ? $value : "'".$value."'";
		$query = 'DELETE FROM `'.$table.'` WHERE `'.$key.'` = '.$value;
		$this->query($query);
		return $this->_affectedRows();
	}
 
	/*
	* @function query
	* @description Perform a native query
	* @param String $query
	* @return void
	*/
	public function query($query){
		$this->res['result'] = mysql_query($query);
	}
 
	/*
	* @function _prepare
	* @description Prepares the query before handing it over to the SQL client
	* @param String $query
	* @return String $query
	*/
	public function _prepare($query){
		return mysql_real_escape_string($query,$this->res['connection']);
	}
 
	/*
	* @function _result(void)
	* @description Fetch the result of a query
	* @return mixed $result
	*/
	public function _result(){
		$result = array();
		while($row=mysql_fetch_assoc($this->res['result'])){
			$result[] = $row;
		}
		return $result;
	}
 
	/*
	* @function _affectedRows(void)
	* @description Fetch the number of rows affected by the last query
	* @return Int $affectedRows
	*/
	public function _affectedRows(){
		return mysql_affected_rows($this->res['connection']);
	}
 
	/*
	* @function _isConnected(void)
	* @description Fetch the connection status
	* @return Bool True|False
	*/
	public function _isConnected(){
		return (bool) is_resource($this->res['connection']);
	}
 
	/*
	* @function _connect
	* @description Connect to the database
	* @param String $host
	* @param String $user
	* @param String $pass
	* @param Int $port
	* @return void
	*/
	public function _connect($host,$user,$pass,$port){
		$this->_disconnect();
		$this->res['connection'] = mysql_connect($host.':'.$port,$user,$pass);
	}
 
	/*
	* @function _selectDb
	* @description Select the database
	* @param String $db
	* @return Bool True|False
	*/
	public function _selectDb($database){
		if($this->_isConnected()){
			return (bool) mysql_select_db($database,$this->res['connection']);
		}
		return false;
	}
 
	/*
	* @function _disconnect(void)
	* @description Disconnect from the database
	* @return void
	*/
	public function _disconnect(){
		if($this->_isConnected()){
			mysql_close($this->res['connection']);
			$this->res['connection'] = null;
		}
	}
 
	/*
	* @function __destruct(void)
	* @description Clean up any open connection
	*/
	function __destruct(){
		$this->_disconnect();
	}
 
}

require_once('db.php');
 
$db = new Db;
$db->connect('mysql://root:lamepass@localhost:3306/test');
/*
* Alternatively you could issue:
$db = new Db('mysql://root:lamepass@localhost:3306/test');
*/
 
echo ($db->driver->_isConnected()) ? 'Connection established' : 'Connection failed'; // returns 'Connection established'

$s = $db->select(array('key','value'),'test');
print_r($s);

echo $db->insert(
	array('key','value'),
	array(
		array('key3','value3'),
		array('key4','value4')
	),
	'test'
); // returns affected rows

$s = $db->select(array('key','value'),'test','WHERE `test`.`key` = \'key3\'');
print_r($s);

echo $db->update(
	array('value'),
	array('value3-2'),
	'test',
	'WHERE `test`.`key` = \'key3\''
); // returns affected rows

$s = $db->select(array('key','value'),'test','WHERE `test`.`key` = \'key3\'');
print_r($s);

echo $db->delete('key','key3','test');

$s = $db->select(array('key','value'),'test');
print_r($s);

class DB_Driver_Dummy implements Db_Driver_Interface {
 
	/*
	* @var $res
	* @description Used to store the connection and result resources
	*/
	var $res;
 
	/*
	* @function __construct(void)
	* @description Populate the resources array
	*/
	function __construct(){
		$this->res = array(
			'connection'	=> false,
			'credentials'	=> array(),
			'result'		=> null,
			'database'		=> array(),
			'rights'		=> array(),
			'affectedRows'	=> 0,
			'dbs'			=> array()
		);
	}
 
	/*
	* @function select
	* @description Select table rows
	* @param Array $fields
	* @param String $table
	* @param String $arguments (optional) ("key=key3,key=key4")
	* @return Array $rows
	*/
	public function select($fields,$table,$arguments=""){
		$t = $this->res['dbs'][$this->res['database']][$table];
		$result = array();
		$keys = $t['keys'];
		$records = $t['records'];
		$ks = $this->res['dbs'][$this->res['database']][$table]['keys'];
		$affectedRows = 0;
 
		if(empty($arguments)){
			foreach($records AS $row){
				$r = array();
				foreach($fields AS $field){
					if(in_array($field,$keys)){
						$r[$field] = $row[$field];
					}
				}
				$result[]=$r;
				$affectedRows++;
			}
		}
		else{
			if(strpos($arguments,',')!==false){
				$keywords = explode(',',$arguments);
			}
			else{
				$keywords = array(trim($arguments));
			}
			$kws = array();
			foreach($keywords AS $keyword){
				$keyword = explode('=',$keyword);
				$kws[$keyword[0]][]=$keyword[1];
			}
 
			for($i=0;$i<count($records);$i++){
				$rac = 0;
				for($j=0;$j<count($ks);$j++){
					$key = $ks[$j];
					$val = $records[$i][$key];
					if(isset($kws[$key])&&in_array($val,$kws[$key])){
						$rac++;
					}
				}				
 
				if($rac==count($kws)){
					$row = $records[$i];
					$r = array();
					foreach($fields AS $field){
						if(in_array($field,$keys)){
							$r[$field] = $row[$field];
						}
					}
					$result[]=$r;
					$affectedRows++;
				}	
			}			
		}
 
		$this->res['result'] = $result;
		$this->res['affectedRows'] = $affectedRows;
		return $this->_result();
	}
 
	/*
	* @function insert
	* @description Insert new row(s) into the table
	* @param Array $keys
	* @param Array mixed (String $values | Array $values)
	* @param String $table
	* @return Int $affectedRows
	*/
	public function insert($keys,$values,$table){
		if(!is_array($values[0])){
			$values = array($values);
		}
 
		foreach($values AS $record){
			$r = array();
			for($i=0;$i<count($record);$i++){
				$r[$keys[$i]]=$record[$i];
			}
			$this->res['dbs'][$this->res['database']][$table]['records'][] = $r;
		}
 
		$this->res['affectedRows'] = count($values);
		return $this->_affectedRows();
	}
 
	/*
	* @function update
	* @description Update row(s) in the table
	* @param Array $keys
	* @param Array mixed (String $values | Array $values)
	* @param String $table
	* @param String $arguments (optional) ("key=key3,key=key4")
	* @return Int $affectedRows
	*/
	public function update($keys,$values,$table,$arguments=""){
		$records = $this->res['dbs'][$this->res['database']][$table]['records'];
		$ks = $this->res['dbs'][$this->res['database']][$table]['keys'];
		$affectedRows = 0;
 
		if(empty($arguments)){
			for($i=0;$i<count($records);$i++){
				for($j=0;$j<count($keys);$j++){
					$records[$i][$keys[$j]] = $values[$j];
				}
				$affectedRows++;
			}
		}
		else{
			if(strpos($arguments,',')!==false){
				$keywords = explode(',',$arguments);
			}
			else{
				$keywords = array(trim($arguments));
			}
			$kws = array();
			foreach($keywords AS $keyword){
				$keyword = explode('=',$keyword);
				$kws[$keyword[0]][]=$keyword[1];
			}
 
			for($i=0;$i<count($records);$i++){
				$rac = 0;
				for($j=0;$j<count($ks);$j++){
					$key = $ks[$j];
					$val = $records[$i][$key];
					if(isset($kws[$key])&&in_array($val,$kws[$key])){
						$rac++;
					}
				}				
 
				if($rac==count($kws)){
					for($j=0;$j<count($keys);$j++){
						$records[$i][$keys[$j]] = $values[$j];
					}
					$affectedRows++;
				}				
			}
		}
 
		$this->res['dbs'][$this->res['database']][$table]['records'] = $records;
		$this->res['affectedRows'] = $affectedRows;
		return $this->_affectedRows();
	}
 
	/*
	* @function delete
	* @description Delete a row from the table
	* @param String $key
	* @param String $value
	* @param String $table
	* @return Int $affectedRows
	*/
	public function delete($key,$value,$table){
		$records = $this->res['dbs'][$this->res['database']][$table]['records'];
		$affectedRows=0;
		for($i=0;$i<count($records);$i++){
			if($records[$i][$key]==$value){
				unset($this->res['dbs'][$this->res['database']][$table]['records'][$i]);
				$affectedRows++;
			}
		}
		$this->res['affectedRows'] = $affectedRows;
		return $this->_affectedRows();
	}
 
	/*
	* @function query
	* @description Perform a native query
	* @param String $query
	* @return void
	*/
	public function query($query){
		// there is no native query support
	}
 
	/*
	* @function _result(void)
	* @description Fetch the result of a query
	* @return mixed $result
	*/
	public function _result(){
		return $this->res['result'];
	}
 
	/*
	* @function _affectedRows(void)
	* @description Fetch the number of rows affected by the last query
	* @return Int $affectedRows
	*/
	public function _affectedRows(){
		return (int) $this->res['affectedRows'];
	}
 
	/*
	* @function _isConnected(void)
	* @description Fetch the connection status
	* @return Bool True|False
	*/
	public function _isConnected(){
		return (bool) $this->res['connection'];
	}
 
	/*
	* @function _connect
	* @description Connect to the database
	* @param String $host
	* @param String $user
	* @param String $pass
	* @param Int $port
	* @return void
	*/
	public function _connect($host,$user,$pass,$port){
		$this->_disconnect();
 
		$this->res['credentials'] = array(
			'host'		=>	$host,
			'user'		=>	$user,
			'database'	=>	$port
		);
 
		$dummy_file = $host.'/.iamdummy';
		$auth_file = $host.'/auth';
		$dbs_file = $host.'/dbs';
 
		if(file_exists($dummy_file)&&file_exists($auth_file)&&file_exists($dbs_file)){
			$auth = trim(file_get_contents($auth_file));
			$auth = explode("\n\n",$auth);
 
			foreach($auth AS $usr){
				$usr = explode("\n",$usr);
				if($usr[0]==$user.':'.$pass){
					$rights = $usr;
					unset($rights[0]);
 
					$ra = array();
					$cur_db = '';
					foreach($rights AS $rs){
						$rs = explode(':',$rs);
						if(substr($rs[0],0,1)=='['){
							$cur_db = trim($rs[0],'[]');
							$cur_rights = explode(',',$rs[1]);
							$ra[$cur_db] = array(
								'rights'	=>	$cur_rights,
								'tables'	=>	array()
							);
						}
						else{
							$cur_table = substr($rs[0],3,-1);
							$cur_rights = explode(',',$rs[1]);
							$ra[$cur_db]['tables'][$cur_table]=$cur_rights;
						}
					}
					$this->res['rights'] = $ra;
					$this->res['connection'] = true;
				}
			}
 
			$dbs = trim(file_get_contents($dbs_file));
			$dbs = explode("\n\n",$dbs);
 
			$dba = array();
			$cur_db = '';
			foreach($dbs AS $db){
				$db = explode("\n",$db);
				$cur_db = trim(array_shift($db),'[]');
				$dba[$cur_db] = array(); // Database can be empty
				$cur_table = '';
				foreach($db AS $table){
					if(substr($table,0,2)=='=>'){
						$cur_table = substr(trim($table),3,-1);
						$cur_table = explode(']:[',$table);
						$keys = explode(',',rtrim($cur_table[1],']'));
						$cur_table = str_replace('=>[','',$cur_table[0]);
						$dba[$cur_db][$cur_table] = array(
							'keys' => $keys,
							'records' => array()
						);
					}
					else{
						$record = explode(',',substr($table,4,-1));
						$r = array();
						$ks = $dba[$cur_db][$cur_table]['keys'];
						for($i=0;$i<count($record);$i++){
							$r[$ks[$i]]=$record[$i];
						}
						$dba[$cur_db][$cur_table]['records'][]=$r;
					}
				}
			}
			$this->res['dbs']=$dba;
 
			$this->_selectDb($port);
		}
	}
 
	/*
	* @function _selectDb
	* @description Select the database
	* @param String $db
	* @return Bool True|False
	*/
	public function _selectDb($database){
		if(isset($this->res['rights'][$database])&&isset($this->res['dbs'][$database])){
			$this->res['database']=$database;
		}
	}
 
	/*
	* @function _disconnect(void)
	* @description Disconnect from the database
	* @return void
	*/
	public function _disconnect(){
		if($this->_isConnected()){
			$dbs_file = $this->res['credentials']['host'].'/dbs';
			$dbs_data = '';
			foreach($this->res['dbs'] AS $database=>$tables){
				$dbs_data .= '['.$database.']';
				foreach($tables AS $table=>$data){
					$keys = $data['keys'];
					$rows = $data['records'];
 
					$dbs_data .= "\n".'=>['.$table.']:['.implode(',',$keys).']';
					foreach($rows AS $row){
						$ro = array();
						foreach($keys AS $key){
							$ro[] = $row[$key];
						}
						$dbs_data .= "\n".'==>['.implode(',',$ro).']';
					}
				}
				$dbs_data .= "\n\n";
			}
			$dbs_data = rtrim($dbs_data);
			file_put_contents($dbs_file,$dbs_data);
		}
		$this->__construct(); // reset values
	}
 
	/*
	* @function __destruct(void)
	* @description Clean up any open connection
	*/
	function __destruct(){
		$this->_disconnect();
	}
 
}

require_once('db.php');
 
$db = new Db('dummy://johmanx:lamepass@dummy/test');
 
echo ($db->driver->_isConnected()) ? 'Connection established' : 'Connection failed'; // returns 'Connection established'

$s = $db->select(array('key','value'),'test');
print_r($s);

echo $db->insert(
	array('key','value'),
	array(
		array('key3','value3'),
		array('key4','value4')
	),
	'test'
); // returns affected rows

$s = $db->select(array('key','value'),'test','key=key3');
print_r($s);

echo $db->update(
	array('value'),
	array('value3-2'),
	'test',
	'key=key3'
); // returns affected rows

$s = $db->select(array('key','value'),'test','key=key3');
print_r($s);

echo $db->delete('key','key3','test');

$s = $db->select(array('key','value'),'test');
print_r($s);