<?php

declare( strict_types=1 );

namespace AcezSeo\Robots;

use AcezSeo\Data\RobotsTxtRepositoryInterface;

if ( ! defined( 'ABSPATH' ) )
{
	exit;
}

/**
 * Appends our robots.txt rules via WP core's `robots_txt` filter (used inside
 * do_robots() for the virtual /robots.txt endpoint). Never runs when a
 * physical robots.txt file exists at the site root — in that case the
 * webserver serves the file directly and no PHP code, including WordPress
 * itself, ever sees the request.
 */
final class RobotsTxtProvider
{
	private RobotsTxtRepositoryInterface $repository;

	public function __construct( RobotsTxtRepositoryInterface $repository )
	{
		$this->repository = $repository;
	}

	public function register(): void
	{
		if ( self::has_physical_file() )
		{
			return;
		}

		add_filter( 'robots_txt', array( $this, 'append_rules' ) );
	}

	public function append_rules( string $output ): string
	{
		$addition = RobotsTxtBuilder::build( $this->repository->get() );

		if ( '' === $addition )
		{
			return $output;
		}

		return rtrim( $output ) . "\n\n" . $addition . "\n";
	}

	public static function has_physical_file(): bool
	{
		return file_exists( ABSPATH . 'robots.txt' );
	}
}