<?php
/**
 * Database Engine Class (db_engine.class.php)
 *
 * This class creates a dabase engine object to interface
 * with a MySQL Database
 * @author Ralfe Poisson <ralfepoisson@gmail.com>
 * @version 1.0
 * @package skyNomad
 */
  
/**
 * DB_Engine
 * @package skyNomad
 * @subpackage classes
 */ 
class db_engine {
	# --- Variables ---
	# Public
	/**
	* Contains the MySQL Host
	* @access public
	* @var string
	*/
	public $mysql_host;
	/**
	* Contains the MySQL Username
	* @access public
	* @var string
	*/
	public $mysql_user;
	/**
	* Contains the MySQL Password
	* @access public
	* @var string
	*/
	public $mysql_pass;
	/**
	* Contains the MySQL Database to acces
	* @access public
	* @var string
	*/
	public $mysql_db;
	
	# Private
	/**
	* Contains the Database Handler
	* @access private
	* @var mysql_connection
	*/
	private $link;
	/**
	* Contains the Logging Engine
	* @access private
	* @var global_log
	*/
	private $logger;
	/**
	* Contains the Database Connection Status
	* @access private
	* @var string
	*/
	private $status;
	/**
	* Sets whether or not to turn Debuggin on
	* @access private
	* @var string
	*/
	private $debug;
	
	# --- Functions ---
	/**
	* Constructor sets up {$mysql_host, $mysql_user, $mysql_pass, $mysql_db, $debug}
	*/
	function db_engine($mysql_host="", $mysql_user="", $mysql_pass="", $mysql_db="", $debug="0"){
		# Initialise Variables
		$this->mysql_host = $mysql_host;
		$this->mysql_user = $mysql_user;
		$this->mysql_pass = $mysql_pass;
		$this->mysql_db = $mysql_db;
		$this->debug = $debug;
		$this->logger = 0;
	}

	/**
	 * Connects to the MySQL database and sets up the database handler.
	*/
	function db_connect(){
		# Create Connection To Database
		if ($this->mysql_host && $this->mysql_user && $this->mysql_pass){
			$this->link = mysql_connect($this->mysql_host, $this->mysql_user, $this->mysql_pass);
		}
		else if ($this->mysql_host && $this->mysql_user && !($tyhis->mysql_pass)){
			$this->link = mysql_connect($this->mysql_host, $this->mysql_user);
		}
		else if ($this->mysql_host && !($this->mysql_user) && !($tyhis->mysql_pass)){
			$this->link = mysql_connect($this->mysql_host);
		}
		
		# Handle any errors
		$this->err_handler(mysql_error());
		
		# Set Database
		if ($this->mysql_db){
			mysql_select_db($this->mysql_db, $this->link);
		}
		
		# Handle any errors
		$this->err_handler(mysql_error());
	}
	
	/**
	 * Connects to the database, executes a query, returns the result
	 * if needed, and closes the connection.
	 * @param string $query The SQL query to execute. 
	 * @return mysql_result
	*/
	function query($query){
		# Connect To Database
		$this->db_connect();
		
		# Execute SQL Command
		$result = mysql_query($query);
		
		# Handle Errors
		$this->err_handler(mysql_error());
		
		# Return Result
		return $result;
	}
	
	/**
	 * Handles any errors that are generated by MySQL. If $debug is set
	 * to true, then the error will be displayed.
	 * @param mysql_error $err The MySQL Error object.
	*/
	function err_handler($err){
		if ($err) {
			if ($this->debug){
				# Output error
				print "<div class='error'><b>DB Error</b>: " . $err . "</div>\n";
				die();
			}
		}
	}
	
	/**
	 * Updates the data of a row in a table.
	 * @param string $table The table name to update.
	 * @param array $data An array with the new values.
	 * @param array $id The index of the row to update.
	*/
	function update_table($table, $data, $id) {
		# Construct Update Query
		$query = "UPDATE `$table`";
		$x = 0;
		foreach ($data as $d){
			if ($x == 0){
				$query .= "SET ";
				$query .= "`" . $d[0] . "` = '" . $d[1] . "' ";
			}
			else {
				$query .= ", `" . $d[0] . "` = '" . $d[1] . "'";
			}
			$x++;
		}
		$query .= " WHERE `" . $id[0] . "` = '" . $id[1] . "'";
		
		# Execute Query
		$this->query($query);
	}
	
	/**
	 * Sets the MySQL Host
	*/
	function set_mysql_host($data){
		$this->mysql_host = $data;
	}
	
	/**
	 * Sets the MySQL Host
	*/
	function set_logger($logger){
		$this->logger = $logger;
	}
	
	/**
	 * Sets the MySQL Username
	*/
	function set_mysql_user($data){
		$this->mysql_user = $data;
	}
	
	/**
	 * Sets the MySQL Password
	*/
	function set_mysql_pass($data){
		$this->mysql_pass = $data;
	}
	
	/**
	 * Sets the MySQL Database
	*/
	function set_mysql_db($data){
		$this->mysql_db = $data;
	}
	
	/**
	 * Turns debuggin mode on or off
	*/
	function set_debug($debug){
		$this->debug = $debug;
	}
}

?>