<?php
/**
 * Minimal lazy service container.
 *
 * @package ProfitEngine
 */

declare( strict_types=1 );

namespace ProfitEngine\Infrastructure;

defined( 'ABSPATH' ) || exit;

use RuntimeException;

/**
 * A tiny PSR-11-flavoured container.
 *
 * Services are registered as factory closures and instantiated lazily the first
 * time they are requested. Resolved instances are cached (singleton semantics),
 * which is what we want for services and repositories in a request lifecycle.
 */
class Container {

	/**
	 * Registered factory closures, keyed by identifier.
	 *
	 * @var array<string, callable>
	 */
	private array $factories = array();

	/**
	 * Resolved singleton instances, keyed by identifier.
	 *
	 * @var array<string, mixed>
	 */
	private array $instances = array();

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

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

	/**
	 * Resolve a service, instantiating (and caching) it on first access.
	 *
	 * @param string $id Service identifier.
	 * @return mixed
	 *
	 * @throws RuntimeException When no factory is registered for the id.
	 */
	public function get( string $id ) {
		if ( array_key_exists( $id, $this->instances ) ) {
			return $this->instances[ $id ];
		}

		if ( ! isset( $this->factories[ $id ] ) ) {
			throw new RuntimeException(
				sprintf( 'ProfitEngine container: no service registered for "%s".', esc_html( $id ) )
			);
		}

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

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