t1gor/Robots.txt-Parser-Class

<?php declare(strict_types=1);

namespace t1gor\RobotsTxtParser;

abstract class Directive {

    /**
     * @link https://yandex.com/support/webmaster/robot-workings/allow-disallow.html#allow-disallow
     */
    const ALLOW = 'allow';
    const DISALLOW = 'disallow';

    const HOST = 'host';

    /**
     * @link https://yandex.com/support/webmaster/robot-workings/sitemap.html#sitemap
     */
    const SITEMAP = 'sitemap';

    /**
     * @link https://yandex.com/support/webmaster/robot-workings/user-agent.html#user-agent
     */
    const USERAGENT = 'user-agent';
    const CACHE = 'cache';
    const CACHE_DELAY = 'cache-delay';

    /**
     * @link https://yandex.com/support/webmaster/robot-workings/clean-param.html#clean-param
     */
    const CLEAN_PARAM = 'clean-param';

    /**
     * @link https://yandex.com/support/webmaster/robot-workings/crawl-delay.html#crawl-delay
     */
    const CRAWL_DELAY = 'crawl-delay';

    /**
     * Extended standard directives
     *
     * @link http://www.conman.org/people/spc/robots2.html
     */
    const REQUEST_RATE = 'request-rate';
    const VISIT_TIME = 'visit-time';

    public static function getAll(): array {
        return [
            self::ALLOW,
            self::DISALLOW,
            self::HOST,
            self::SITEMAP,
            self::USERAGENT,
            self::CRAWL_DELAY,
            self::CACHE_DELAY,
            self::CLEAN_PARAM,
            self::REQUEST_RATE,
            self::VISIT_TIME,
        ];
    }

    public static function getRegex(): string {
        return "/^(?!(" . implode('|', Directive::getAll()) . ")\s*:+).+/mui";
    }

    public static function getRequestRateRegex(): string {
        return "/^" . self::REQUEST_RATE . ":+\s*(?![0-9]+\/[0-9]+).*/mui";
    }

    public static function getCrawlDelayRegex(): string {
        return "/^" . self::CRAWL_DELAY . ":+\s*(\D+)$/mui";
    }

    /**
     * @TODO finish me
     * @return string
     */
    public static function getAllowDisallowRegex(): string {
        return "/^(" . self::ALLOW . "|" . self::DISALLOW . "):+\s*\\{1}.*$/mui";
    }

    public static function attemptGetInline(string $rule) {
        foreach (static::getAll() as $directive) {
            if (0 === strpos(mb_strtolower($rule), $directive . ':')) {
                return $directive;
            }
        }
        return false;
    }

    public static function stripInline(string $rule): string {
        $directive = static::attemptGetInline($rule);

        if ($directive !== false) {
            $rule = trim(str_ireplace($directive . ':', '', $rule));
        }

        return $rule;
    }
}