silverstripe-cms/code/sitefeatures/MathSpamProtection.php

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<?php
/**
* Tools for adding an optional protection question to a form.
* Remember to add MathSpamProtection::enabled(true); to _config.php for this question to be added to the comments form.
*/
class MathSpamProtection {
private static $mathProtection = false;
static function isEnabled() {
return (self::$mathProtection != null) ? true : false;
}
static function setEnabled($math = true) {
MathSpamProtection::$mathProtection = $math;
}
/**
* Creates the question from random variables, which are also saved to the session.
*/
static function getMathQuestion(){
if(!Session::get("mathQuestionV1")&&!Session::get("mathQuestionV2")){
$v1 = rand(1,9);
$v2 = rand(1,9);
Session::set("mathQuestionV1",$v1);
Session::set("mathQuestionV2",$v2);
}
else{
$v1 = Session::get("mathQuestionV1");
$v2 = Session::get("mathQuestionV2");
}
return "What is ".MathSpamProtection::digitToWord($v1)." plus ".MathSpamProtection::digitToWord($v2)."?";
}
/**
* Checks the given answer if it matches the addition of the saved session variables. Users can answer using words or digits.
*/
static function correctAnswer($answer){
$v1 = Session::get("mathQuestionV1");
$v2 = Session::get("mathQuestionV2");
return (MathSpamProtection::digitToWord($v1 + $v2) == $answer || ($v1 + $v2) == $answer) ? true : false;
}
/**
* Helper method for converting digits to their equivelant english words
*/
static function digitToWord($num){
$numbers = array("zero","one","two","three","four","five","six","seven","eight","nine",
"ten","eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen","eighteen");
if($num < 0){
return "minus ".($numbers[-1*$num]);
}
//TODO: add checking or return null for bad value??
return $numbers[$num];
}
}
?>