class.ilHttpRequestsLanguageDetector.php

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<?php

declare(strict_types=1);

class ilHttpRequestsLanguageDetector implements ilLanguageDetector
{
    protected string $header_value;

    public function __construct(string $header_value)
    {
        $this->header_value = $header_value;
    }

    public function getIso2LanguageCode(): string
    {
        if (strlen($this->header_value)) {
            $matches = array();
            // Format: de,de-DE;q=0.8,en-US;q=0.6,en;q=0.4
            preg_match_all("/([a-z]{1,8}(-[a-z]{1,8})?)\s*(;\s*q\s*=\s*(1|0\.[0-9]+))?/i", $this->header_value, $matches);
            if (count($matches[1])) {
                $langs = array_combine($matches[1], $matches[4]);
                foreach ($langs as $lang => $val) {
                    if ($val === '') {
                        $langs[$lang] = 1;
                    }
                }
                arsort($langs, SORT_NUMERIC);

                $keys = array_keys($langs);
                if (isset($keys[0])) {
                    return substr($keys[0], 0, 2);
                }
            }
        }

        throw new ilLanguageException("Could not extract any language information from request.");
    }
}