summaryrefslogtreecommitdiff
path: root/extensions/ConfirmEdit/MathCaptcha.class.php
blob: 220df31da583932c19ff47b9566c1f2709e25dda (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
<?php

class MathCaptcha extends SimpleCaptcha {

	/** Validate a captcha response */
	function keyMatch( $answer, $info ) {
		return (int)$answer == (int)$info['answer'];
	}

	function addCaptchaAPI( &$resultArr ) {
		list( $sum, $answer ) = $this->pickSum();
		$index = $this->storeCaptcha( array( 'answer' => $answer ) );
		$resultArr['captcha']['type'] = 'math';
		$resultArr['captcha']['mime'] = 'text/tex';
		$resultArr['captcha']['id'] = $index;
		$resultArr['captcha']['question'] = $sum;
	}

	/** Produce a nice little form */
	function getForm() {
		list( $sum, $answer ) = $this->pickSum();
		$index = $this->storeCaptcha( array( 'answer' => $answer ) );

		$form = '<table><tr><td>' . $this->fetchMath( $sum ) . '</td>';
		$form .= '<td>' . Xml::input( 'wpCaptchaWord', false, false, array( 'tabindex' => '1' ) ) . '</td></tr></table>';
		$form .= Html::hidden( 'wpCaptchaId', $index );
		return $form;
	}

	/** Pick a random sum */
	function pickSum() {
		$a = mt_rand( 0, 100 );
		$b = mt_rand( 0, 10 );
		$op = mt_rand( 0, 1 ) ? '+' : '-';
		$sum = "{$a} {$op} {$b} = ";
		$ans = $op == '+' ? ( $a + $b ) : ( $a - $b );
		return array( $sum, $ans );
	}

	/** Fetch the math */
	function fetchMath( $sum ) {
		// class_exists() unfortunately doesn't work with HipHop, and
		// its replacement, MWInit::classExists(), wasn't added until
		// MW 1.18, and is thus unusable here - so instead, we'll
		// just duplicate the code of MWInit::classExists().
		try {
			$r = new ReflectionClass( 'MathRenderer' );
		} catch( ReflectionException $r ) {
			throw new MWException( 'MathCaptcha requires the Math extension for MediaWiki versions 1.18 and above.' );
		}

		$math = new MathRenderer( $sum );
		$math->setOutputMode( MW_MATH_PNG );
		$html = $math->render();
		return preg_replace( '/alt=".*?"/', '', $html );
	}
}