<?php
/* is_valid_email_regexp is dual licensed under the GNU GPL v3 (or later) and
 * under the MIT license.
 *
 * is_valid_email_regexp is available from http://rumkin.com/software/email/
 *
 * is_valid_email_regexp uses PHP and regular expressions to determine if
 * an email appears to be valid.
 */
define('EMAIL_PATTERN_QTEXT', '[\\x01-\\x08\\x0B\\x0C\\x0E-\\x21\\x23-\\x5A\\x5E-\\x7F]');
define('EMAIL_PATTERN_QTEXTMORE', '[\\x01-\\x09\\x0B\\x0C\\x0E-\\x7F]');
define('EMAIL_PATTERN_TEXT', '[\\x21\\x23-\\x27\\x2A-\\x2B\\x2D\\x2F-\\x39\\x3D\\x3F\\x41-\\x5A\\x5E-\\x7E]');
define('EMAIL_PATTERN_QUOTE', '(' . EMAIL_PATTERN_QTEXT . '|\\\\' . EMAIL_PATTERN_QTEXTMORE . ')');
define('EMAIL_PATTERN_TEXT_OR_QUOTE', '(' . EMAIL_PATTERN_TEXT . '+|"' . EMAIL_PATTERN_QUOTE . '*")');
define('EMAIL_PATTERN_LOCALPART', EMAIL_PATTERN_TEXT_OR_QUOTE . '(\\.' . EMAIL_PATTERN_TEXT_OR_QUOTE . ')*');
define('EMAIL_PATTERN_DOMAIN_LABEL', '[0-9A-Za-z](-?[0-9A-Za-z])*');
define('EMAIL_PATTERN_DOMAIN_LABEL_TLD', '[A-Za-z]+');
define('EMAIL_PATTERN_DOMAIN_NORMAL', '(' . EMAIL_PATTERN_DOMAIN_LABEL . '\\.)*' . EMAIL_PATTERN_DOMAIN_LABEL_TLD);
define('EMAIL_PATTERN_DOMAIN_QTEXT', '[\\x01-\\x08\\x0B\\x0C\\x0E-\\x21\\x23-\\x2C\\x2E-\\x5A\\x5E-\\x7F]');
define('EMAIL_PATTERN_DOMAIN_QUOTE', '(' . EMAIL_PATTERN_DOMAIN_QTEXT . '(-?' . EMAIL_PATTERN_DOMAIN_QTEXT . ')*|\\\\' . EMAIL_PATTERN_QTEXTMORE . ')');
define('EMAIL_PATTERN_DOMAIN_BRACKET', '\\[' . EMAIL_PATTERN_DOMAIN_QUOTE . '*\\]');
define('EMAIL_PATTERN_DOMAIN_IPV6', '[0-9a-f]{4}:[0-9a-f]{4}::[0-9a-f]{4}:[0-9a-f]{4}');
define('EMAIL_PATTERN_DOMAIN_IPV4', '([012]?[0-9]{1,2}\\.){3}[012]?[0-9]?[0-9]');
define('EMAIL_PATTERN_DOMAIN_IP', '(' . EMAIL_PATTERN_DOMAIN_IPV4 . '|' . EMAIL_PATTERN_DOMAIN_IPV6 . ')');


function is_valid_email_regexp($email) {
    $email = trim($email);

    // Some quick checks
    if (strpos($email, "\t") !== false || strpos($email, "\r") !== false || strpos($email, "\n") !== false) {
        return false;
    }

    if ($email == '') {
        return true;
    }

    if (strlen($email) > 320) {
        return false;
    }

    if (! preg_match('/^' . EMAIL_PATTERN_LOCALPART . '@/', $email, $matches)) {
        return false;
    }

    if (strlen($matches[0]) > 65) {
        // 64 character max for the local part + 1 character for @
        return false;
    }

    $domain = substr($email, strlen($matches[0]));

    if (! preg_match('/^' . EMAIL_PATTERN_DOMAIN_NORMAL . '$/', $domain)) {
        if (preg_match('/^' . EMAIL_PATTERN_DOMAIN_IP . '$/', $domain)) {
            return true;
        }

        if (preg_match('/^' . EMAIL_PATTERN_DOMAIN_BRACKET . '$/', $domain)) {
            $domain = trim(substr($domain, 1, strlen($domain) - 2));
        } else {
            return false;
        }
    }

    if (strlen($domain) > 253) {
        return false;
    }

    $labels = array();
    $thisLabel = '';
    $domainSplit = str_split($domain);

    while (count($domainSplit)) {
        if ($domainSplit[0] == '.') {
            array_shift($domainSplit);

            if ($thisLabel == '') {
                return false;
            }

            $labels[] = $thisLabel;
            $thisLabel = '';
        } else {
            if ($domainSplit[0] == '\\') {
                $thisLabel .= array_shift($domainSplit);
            }

            $thisLabel .= array_shift($domainSplit);
        }
    }

    if ($thisLabel == '') {
        return false;
    }

    if (! preg_match('/^[a-zA-Z]{1,63}$/', $thisLabel)) {
        return false;
    }

    foreach ($labels as $label) {
        if (strlen($label) > 63) {
            return false;
        }

        if (substr($label, 1) == '-' || substr($label, - 1) == '-' || strpos($label, '--') !== false) {
            return false;
        }
    }

    return true;
}