Solar e-mail helper that stops spammers

Tonight I created a helper for Solar that encodes mailto href addresses so SPAMers that scrape HTML pages will never get your addresses.

To use this helper, just do the following in your views/layouts:

echo $this->email('someuser@somehost.com', 'Ray');

Here is the helper code:

<?php
/**
 * Generates an encoded mailto href to stop spammers from scrapping email
 * addresses from your web pages.  This code is based on the PHP example
 * from http://rumkin.com/tools/mailto_encoder/
 *
 * @category Whitebox
 * @package Whitebox_View
 * @author Raymond J. Kolbe <rkolbe@gmail.com>
 */
class Whitebox_View_Helper_Email extends Solar_View_Helper {
    /**
     * The encoded email address.
     *
     * @var string
     */
    protected $_encoded_string = '';
    /**
     * The encoded index used to decode $_encoded_string/
     *
     * @var string
     */
    protected $_encoded_indexes = '';
    /**
     * Generates an encoded mailto href to stop spammers from
     * scrapping email addresses off your web pages.  Returns
     * an inline javascript code block that allows web browser
     * to read the mailto href.
     *
     * If javascript is disabled in the web browser, only the
     * link text is shown to the user.
     *
     * @param string $spec The email address (e.g. rkolbe@gmail.com)
     * @param string $text Href
     * @param array $attribs An array of href attributes
     * @return string An inline string of javascript to handle the
     * encoded mailto href
     */
    public function email($spec, $text = null, $attribs = null) {
        // escape the email address
        $spec = $this->_view->escape($spec);
        // build attribs, after dropping any 'href' attrib
        $attribs = (array) $attribs;
        unset($attribs['href']);
        $attribs = $this->_view->attribs($attribs);
        $this->_obfuscate("<a href=\"mailto:$spec\"$attribs>$text</a>");
        $script = $this->_getScript();
        $script .= '<noscript>'.$text.'</noscript>';
        return $script;
    }
    /**
     * Takes a given href and obfuscates it.
     *
     * @param string $link A full mailto href
     * @return void
     */
    protected function _obfuscate($link) {
        $scrambled_chars = str_shuffle($link);
        $this->_encoded_string = $this->_escapeString($scrambled_chars);
        $string_indexes = '';
        for ($i = 0; $i < strlen($link); $i++) {
            $index = strpos($scrambled_chars, substr($link, $i, 1)) + 48;
            $string_indexes .= chr($index);
        }
        $this->_encoded_indexes = $this->_escapeString($string_indexes);
    }
    /**
     * Returns a block of javascript used to decode the mailto href.
     * This only allows web browsers to see the mailto address.
     *
     * @param void
     * @return string An inline block of javascript
     */
    protected function _getScript() {
        return $this->_view->scriptInline('<!--
            chars = "'.$this->_encoded_string.'";
            indexes = "'.$this->_encoded_indexes.'";
            href = "";
            for(j = 0; j < indexes.length; j++){
                href += chars.charAt(indexes.charCodeAt(j) - 48);
            }
            document.write(href);
            // -->');
    }
    /**
     * Prepares (escapes) a string for javascript.
     *
     * @param string $string The string to escape
     * @return string The escaped string
     */
    protected function _escapeString($string) {
        $string = str_replace("\\", "\\\\", $string);
        $string = str_replace("\"", "\\\"", $string);
        return $string;
    }
}