<?php
/**
 * Captcha logic class
 */

include_once(dirname(__FILE__).'/./config.inc.php');

class Captcha {

	private $calcOps;

	function __construct() {
		$this->calcOps = array("+", "-", "*");
	}

	function generateAndUseCaptcha() {
		$rndType = rand(1, 100);
		if ($rndType > 0) {
			// build numeric question
			$useOp = $this->calcOps[rand(0, 2)];
			$firstNum = 0;
			$secondNum = 0;
			if ($useOp == "*") {
				$firstNum = rand(0, 9);
				$secondNum = rand(0, 15);
			} else {
				$firstNum = rand(0, 100);
				$secondNum = rand(0, 100);
			}
			$calc = 0;
			if ($useOp == "+") {
				$calc = $firstNum + $secondNum;
			} else if ($useOp == "-") {
				$calc = $firstNum - $secondNum;
			} else if ($useOp == "*") {
				$calc = $firstNum * $secondNum;
			}
			$mathStr = "" . $firstNum . " " . $useOp . " " . $secondNum;
			$_SESSION['CAPTCHA_QUESTION'] = $mathStr;
			$_SESSION['CAPTCHA_VALUE'] = $calc;
			// field name
			$fieldname = chr(rand(65, 90)) . dechex(rand());
			$_SESSION['CAPTCHA_FIELD'] = $fieldname;
			return $mathStr;
		} else {
			// use pooled question
			// TODO currently not supported due to missing logic which language to use
		}
	}

	function validateCaptcha($inputStr) {
		if (empty($inputStr) == true) {
			return false;
		}
		if (isset($_SESSION['CAPTCHA_VALUE']) == false) {
			return false;
		}
		
		$valueInSession = $_SESSION['CAPTCHA_VALUE'];
		return ($inputStr == $valueInSession . "");
	}

}