<?php
/**
 * CCNumberValidator.class.php
 *
 * This file contains the definition of the CCNumberValidator class.
 *
 * @package SolidWorks
 * @author John Diamond <hide@address.com>
 * @copyright John Diamond <hide@address.com>
 * @license http://www.opensource.org/licenses/gpl-license.php GNU Public License
 */

/**
 * CCNumberValidator
 *
 * @package SolidWorks
 * @author John Diamond <hide@address.com>
 */
class CCNumberValidator extends TextValidator {
	/**
	 * Validate a Credit Card Number
	 *
	 * Strips out unwanted characters, then applies a simple length test (13-16
	 * digits) and the MOD 10 algorithm.
	 *
	 * @param string $data Field data
	 * @return string Credit card number (digits only)
	 * @throws FieldException
	 */
	public function validate( $data ) {
		$data = parent::validate( $data );

		// Strip out unwanted characters
		$data = preg_replace( "|[^0-9]|", "", $data );

		// Test the number's length
		if ( strlen( $data ) < 13 || strlen( $data ) > 16 ) {
			throw new FieldException();
		}

		// Apply the MOD 10 algorithm
		$revNumber = strrev( $data );
		$numSum = 0;
		for ( $i = 0; $i < strlen( $revNumber ); $i++ ) {
			$currentNum = substr( $revNumber, $i, 1 );

			// Double every second digit
			$currentNum = ($i % 2 == 1) ? $currentNum * 2 : $currentNum;

			// Add digits of 2-digit numbers together
			if ( $currentNum > 9 ) {
				$firstNum = $currentNum % 10;
				$secondNum = ($currentNum - $firstNum) / 10;
				$currentNum = $firstNum + $secondNum;
			}

			$numSum += $currentNum;
		}
		if ( $numSum % 10 != 0 ) {
			// The CC number failed the MOD 10 test
			throw new FieldException();
		}

		return $data;
	}
}
?>