<?php

namespace WPForms\Vendor;

/**
 * Validates the HTML attribute lang, effectively a language code.
 * @note Built according to RFC 3066, which obsoleted RFC 1766
 */
class HTMLPurifier_AttrDef_Lang extends HTMLPurifier_AttrDef
{
    /**
     * @param string $string
     * @param HTMLPurifier_Config $config
     * @param HTMLPurifier_Context $context
     * @return bool|string
     */
    public function validate($string, $config, $context)
    {
        $string = \trim($string);
        if (!$string) {
            return \false;
        }
        $subtags = \explode('-', $string);
        $num_subtags = \count($subtags);
        if ($num_subtags == 0) {
            // sanity check
            return \false;
        }
        // process primary subtag : $subtags[0]
        $length = \strlen($subtags[0]);
        switch ($length) {
            case 0:
                return \false;
            case 1:
                if (!($subtags[0] == 'x' || $subtags[0] == 'i')) {
                    return \false;
                }
                break;
            case 2:
            case 3:
                if (!\ctype_alpha($subtags[0])) {
                    return \false;
                } elseif (!\ctype_lower($subtags[0])) {
                    $subtags[0] = \strtolower($subtags[0]);
                }
                break;
            default:
                return \false;
        }
        $new_string = $subtags[0];
        if ($num_subtags == 1) {
            return $new_string;
        }
        // process second subtag : $subtags[1]
        $length = \strlen($subtags[1]);
        if ($length == 0 || $length == 1 && $subtags[1] != 'x' || $length > 8 || !\ctype_alnum($subtags[1])) {
            return $new_string;
        }
        if (!\ctype_lower($subtags[1])) {
            $subtags[1] = \strtolower($subtags[1]);
        }
        $new_string .= '-' . $subtags[1];
        if ($num_subtags == 2) {
            return $new_string;
        }
        // process all other subtags, index 2 and up
        for ($i = 2; $i < $num_subtags; $i++) {
            $length = \strlen($subtags[$i]);
            if ($length == 0 || $length > 8 || !\ctype_alnum($subtags[$i])) {
                return $new_string;
            }
            if (!\ctype_lower($subtags[$i])) {
                $subtags[$i] = \strtolower($subtags[$i]);
            }
            $new_string .= '-' . $subtags[$i];
        }
        return $new_string;
    }
}
// vim: et sw=4 sts=4
