<?php

class DB {

	protected $db_name = 'dbName';
	protected $db_user = 'webApp';
	private $db_pass = 'dbPass';
	protected $db_host = 'localhost';
	private $PDO = 0;

	//connect to db
	public function __construct()
	{
		try
		{
			$PDO = new PDO( 'mysql:host='.$this->db_host.';dbname='.$this->db_name, $this->db_user, $this->db_pass);
			$this->PDO = $PDO;
		}
		catch (PDOException $e)
		{
			return "Error!: " . $e->getMessage() . "<br/>";
			$this->PDO = 0;
    	die();
		}
	}

	//simple query - query is a query string, params is 1-dimension an array of parameters
  //used as prepared statements, so amount and order of members in params must match the placeholders in the query
	public function querySimple ($query, $params)
	{
		try
		{
			if ($this->PDO !== 0 && is_array($params))
			{
				$this->PDO->beginTransaction();
				$stmt = $this->PDO->prepare($query);

				$stmt->execute($params);
				$result = $stmt->fetchAll();
				$this->PDO->commit();
				return $result;
			}
			else
			{
				$this->PDO->rollBack();
				return "Error: <br /> Query =".$query.", $params is array = ".is_array($params);
				die();
			}

		}
		catch (Throwable $e)
		{
			$this->PDO->rollBack();
			return "Error!: " . $e->getMessage() . "<br/>";
			die();
		}
	}

	//batch query - when you need to update multiple valueswith different criterias, use this one
	//don't use for selects - it won't return any records
	//here $params will be two-dimensional - array that contains arrays of values
	public function queryBatch ($query, $params)
	{
		try
		{
			if ($this->PDO !== 0 && is_array($params))
			{
				$this->PDO->beginTransaction();
				$stmt = $this->PDO->prepare($query);
				foreach ($params as $paramArray)
				{
					if (is_array($paramArray))
					{
						foreach ($paramArray as $key=>$param)
							$stmt->bindValue(($key+1),$param);

						$stmt->execute();
					}
					else
					{
						$this->PDO->rollBack();
						print "<pre>Error in one of the subarrays:<br />$params is array = ".is_array($params).'<br>';
						var_dump($param);
						print '</pre>';
						die();
					}
				}
				$this->PDO->commit();
				return 'ok';
			}
			else
			{
				$this->PDO->rollBack();
				return "Error: <br /> Query =".$query.", $params is array = ".is_array($params);
				die();
			}
		}

		catch (Throwable $e)
		{
			$this->PDO->rollBack();
			return "Error!: " . $e->getMessage() . "<br/>";
			die();
		}
	}




}

?>