1 files changed, 50 insertions, 0 deletions
diff --git a/extensions/ConfirmEdit/MathCaptcha/MathCaptcha.class.php b/extensions/ConfirmEdit/MathCaptcha/MathCaptcha.class.php
new file mode 100644
index 00000000..d3e4af69
--- /dev/null
+++ b/extensions/ConfirmEdit/MathCaptcha/MathCaptcha.class.php
@@ -0,0 +1,50 @@
+<?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>' . Html::input( 'wpCaptchaWord', false, false, array( 'tabindex' => '1', 'autocomplete' => 'off', 'required' ) ) . '</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 ) {
+		if ( class_exists( 'MathRenderer' ) ) {
+			$math = MathRenderer::getRenderer( $sum, array(), MW_MATH_PNG );
+		} else {
+			throw new Exception( 'MathCaptcha requires the Math extension for MediaWiki versions 1.18 and above.' );
+		}
+		$html = $math->render();
+		return preg_replace( '/alt=".*?"/', '', $html );
+	}
+}