<?php
/**
 * Dependency injection container.
 *
 * @package AgentFirewall
 */

declare(strict_types=1);

namespace AgentFirewall;

use Closure;
use RuntimeException;

defined( 'ABSPATH' ) || exit;

/**
 * Minimal service container: string ids mapped to lazy factories, resolved
 * instances shared for the lifetime of the request.
 */
final class Container {

	/**
	 * Registered service factories.
	 *
	 * @var array<string, Closure>
	 */
	private array $factories = array();

	/**
	 * Resolved shared instances.
	 *
	 * @var array<string, mixed>
	 */
	private array $instances = array();

	/**
	 * Register a service factory.
	 *
	 * @param string  $id      Service identifier.
	 * @param Closure $factory Factory receiving this container, returning the service.
	 */
	public function set( string $id, Closure $factory ): void {
		$this->factories[ $id ] = $factory;
		unset( $this->instances[ $id ] );
	}

	/**
	 * Resolve a service, instantiating it on first access.
	 *
	 * @param string $id Service identifier.
	 * @return mixed
	 * @throws RuntimeException When the id was never registered.
	 */
	public function get( string $id ): mixed {
		if ( array_key_exists( $id, $this->instances ) ) {
			return $this->instances[ $id ];
		}

		if ( ! isset( $this->factories[ $id ] ) ) {
			throw new RuntimeException(
				sprintf( 'Container: unknown service "%s".', esc_html( $id ) )
			);
		}

		$this->instances[ $id ] = ( $this->factories[ $id ] )( $this );

		return $this->instances[ $id ];
	}

	/**
	 * Whether a service id is registered.
	 *
	 * @param string $id Service identifier.
	 */
	public function has( string $id ): bool {
		return isset( $this->factories[ $id ] );
	}
}