<?php

class MySQL
{
	private $result = NULL;
	private $link = NULL;
	private static $instance = NULL;

	// return Singleton instance of MySQL class
	public static function getInstance(array $config = array())
	{
		if (self::$instance === NULL)
		{
			self::$instance = new self($config);
		}
		return self::$instance;
	}
	
	// constructor
	public function __construct(array $config = array())
	{
        // grab connection parameters
		list($host, $user, $password, $database) = $config;
		if ((!$this->link = mysqli_connect($host, $user, $password, $database)))
		{
			throw new Exception('Error connecting to MySQL : ' . mysqli_connect_error());
		}
	}

    // perform query
    public function query($query)
    {
        if (is_string($query) and !empty($query))
        {
            if ((!$this->result = mysqli_query($this->link, $query)))
            {
                throw new Exception('Error performing query ' . $query . ' Message : ' . mysqli_error($this->link));
            }
        }
    }
    
	// fetch row from result set
	public function fetch()
	{
        if ((!$row = mysqli_fetch_object($this->result)))
        {
            mysqli_free_result($this->result);
            return FALSE;
        }
        return $row;
	}

    // get insertion ID
    public function getInsertID()
    {
        if ($this->result !== NULL)
        {
            return mysqli_insert_id($this->link); 
        }
        return FALSE;
    }
    
    // count rows in result set
    public function countRows()
    { 
        if ($this->result !== NULL)
        {
           return mysqli_num_rows($this->result); 
        }
        return 0;
    }
    
	// close the database connection
	function __destruct()
	{
		is_resource($this->link) and mysqli_close($this->link);
	}
}// End MySQL class