<?php
/** DB.class.php
  * The point of this is to abstract the mechanical tasks
  * involved in connecting to a database.
  *
  * Configuration: expects an ini file
  *
  * Uses the typical getInstance() singleton method.
  *
**/
class DB {

	private $pathToConfigFile = "DB.config.ini";

	private $hostname;
	private $username;
	private $password;
	private $database;
	private $lastQuery;

	public static function getInstance() {
		static $DB;
		if (!isset($DB)) {
			$DB = new DB();
		}
		return $DB;
	}

	public function test() {
		return mysql_ping();
	}

	public function update($sql) {
		mysql_query($sql);
		return mysql_affected_rows();
	}

	public function insert($sql) {
		mysql_query($sql);
		return mysql_insert_id();
	}

	public function delete($sql) {
		mysql_query($sql);
		return mysql_affected_rows();
	}

	// Returns an array of arrays
	public function select($sql) {
		$result = array();
	    $this->setLastQuery($sql);
		$resource = mysql_query($sql);
		if (is_resource($resource)) {
			while ($row = mysql_fetch_assoc($resource)) {
				$result[] = $row;
			}
		}
		return $result;
	}
	
	// Returns an array of field names
	public function getFields($table) {
		$fields = array();
		$resource = mysql_query("SHOW COLUMNS FROM $table;");
		while ($row = mysql_fetch_array($resource)) {
			$fields[$row['Field']] = '';
		}
		return $fields;
	}

	private function __construct() {
		$this->loadSettings($this->pathToConfigFile);
		$conn = mysql_connect($this->hostname, $this->username, $this->password)
			or trigger_error('Error connecting to server: ' . 
				$this->hostname . " " . mysql_error(), E_USER_ERROR);
		mysql_select_db($this->database)
			or trigger_error('Error selecting database ' . 
			$this->database . " " .	mysql_error(), E_USER_ERROR);
	}
	
	public function __destroy() {
		$this->close();
	}

	public function close() {
		return mysql_close();
	}

	public function getLastQuery() {
		return $this->lastQuery;
	}
	
	// Sets the last query. A private utility method.
	private function setLastQuery($sql) {
		$this->lastQuery = $sql;
	}
	
	private function loadSettings($path) {
		foreach(parse_ini_file($path) as $key => $value) {
			$this->$key = $value;
		}
		if (!$this->hostname ||
			!$this->username ||
			!$this->password ||
			!$this->database) {
			trigger_error("DB class could not load settings from " . $path);
		}
	}
}
?>