<?php

/**
 * Validates a number as defined by the CSS spec.
 */
class HTMLPurifier_AttrDef_CSS_Number extends HTMLPurifier_AttrDef {
	
	/**
	 * Indicates whether or not only positive values are allowed.
	 * @type bool
	 */
	protected $non_negative = false;
	
	/**
	 *
	 * @param bool $non_negative
	 *        	indicates whether negatives are forbidden
	 */
	public function __construct($non_negative = false) {
		$this->non_negative = $non_negative;
	}
	
	/**
	 *
	 * @param string $number        	
	 * @param HTMLPurifier_Config $config        	
	 * @param HTMLPurifier_Context $context        	
	 * @return string|bool @warning Some contexts do not pass $config, $context. These
	 *         variables should not be used without checking HTMLPurifier_Length
	 */
	public function validate($number, $config, $context) {
		$number = $this->parseCDATA ( $number );
		
		if ($number === '') {
			return false;
		}
		if ($number === '0') {
			return '0';
		}
		
		$sign = '';
		switch ($number [0]) {
			case '-' :
				if ($this->non_negative) {
					return false;
				}
				$sign = '-';
			case '+' :
				$number = substr ( $number, 1 );
		}
		
		if (ctype_digit ( $number )) {
			$number = ltrim ( $number, '0' );
			return $number ? $sign . $number : '0';
		}
		
		// Period is the only non-numeric character allowed
		if (strpos ( $number, '.' ) === false) {
			return false;
		}
		
		list ( $left, $right ) = explode ( '.', $number, 2 );
		
		if ($left === '' && $right === '') {
			return false;
		}
		if ($left !== '' && ! ctype_digit ( $left )) {
			return false;
		}
		
		$left = ltrim ( $left, '0' );
		$right = rtrim ( $right, '0' );
		
		if ($right === '') {
			return $left ? $sign . $left : '0';
		} elseif (! ctype_digit ( $right )) {
			return false;
		}
		return $sign . $left . '.' . $right;
	}
}

// vim: et sw=4 sts=4