<?php

declare(strict_types=1);

namespace LinkCheckup\Plugin;

use function is_readable;
use function spl_autoload_register;
use function str_replace;
use function str_starts_with;
use function strlen;
use function substr;

final class ClassAutoloader {

	private const NAMESPACE_SEPARATOR = '\\';
	private const DIRECTORY_SEPARATOR = '/';
	private const FILE_EXTENSION      = '.php';

	public function __construct(
		private string $namespace_prefix,
		private string $source_directory
	) {
	}

	public function register(): void {
		spl_autoload_register(
			fn( string $class_name ) => $this->load( $class_name )
		);
	}

	public function load( string $class_name ): void {
		if ( ! str_starts_with( $class_name, $this->namespace_prefix ) ) {
			return;
		}

		$relative_name = substr(
			$class_name,
			strlen( $this->namespace_prefix )
		);
		$class_file    = $this->source_directory . str_replace(
			self::NAMESPACE_SEPARATOR,
			self::DIRECTORY_SEPARATOR,
			$relative_name
		) . self::FILE_EXTENSION;

		if ( ! is_readable( $class_file ) ) {
			return;
		}

		require_once $class_file;
	}
}