<?php

declare(strict_types=1);

namespace LinkCheckup\Features\LinkLists;

use LinkCheckup\Shared\Http\PluginUserAgent;

final class SiteHomeProbe {

	private const HEAD_METHOD          = 'HEAD';
	private const TIMEOUT_SECONDS      = 5;
	private const FOLLOWED_REDIRECTS   = 0;
	private const FIRST_ANSWERING_CODE = 200;
	private const FIRST_FAILING_CODE   = 400;
	private const SCHEME_SEPARATOR     = '://';
	private const HOME_PATH            = '/';

	public function answering_home_of( string $url ): string|null {
		$home     = $this->home_of( $url );
		$response = wp_safe_remote_request(
			$home,
			array(
				'method'      => self::HEAD_METHOD,
				'timeout'     => self::TIMEOUT_SECONDS,
				'redirection' => self::FOLLOWED_REDIRECTS,
				'user-agent'  => PluginUserAgent::NAME,
			)
		);
		$code     = (int) wp_remote_retrieve_response_code( $response );

		return $this->is_answering( $code ) ? $home : null;
	}

	private function home_of( string $url ): string {
		$scheme = (string) wp_parse_url( $url, PHP_URL_SCHEME );
		$host   = (string) wp_parse_url( $url, PHP_URL_HOST );

		return strtolower( $scheme . self::SCHEME_SEPARATOR . $host )
			. self::HOME_PATH;
	}

	private function is_answering( int $code ): bool {
		return self::FIRST_ANSWERING_CODE <= $code
			&& self::FIRST_FAILING_CODE > $code;
	}
}