<?php
/**
 * Minimal service container (no third-party dependencies).
 *
 * @package Extrova
 */

declare( strict_types=1 );

namespace Extrova;

defined( 'ABSPATH' ) || exit;

/**
 * Lazy, shared-instance service container.
 *
 * @since 1.0.0
 */
final class Container {

	/**
	 * Service factories.
	 *
	 * @var array<string, callable>
	 */
	private array $factories = array();

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

	/**
	 * Registers (or replaces) a service factory. The factory receives the container.
	 *
	 * @param string   $id      Service id.
	 * @param callable $factory Factory: fn( Container $c ): mixed.
	 */
	public function set( string $id, callable $factory ): void {
		$this->factories[ $id ] = $factory;
		unset( $this->instances[ $id ] );
	}

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

	/**
	 * Resolves a shared service.
	 *
	 * @param string $id Service id.
	 * @return mixed
	 * @throws \OutOfBoundsException When the service is not 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 \OutOfBoundsException( sprintf( 'Service "%s" is not registered.', esc_html( $id ) ) );
		}
		$this->instances[ $id ] = ( $this->factories[ $id ] )( $this );
		return $this->instances[ $id ];
	}

	/**
	 * Decorates a registered service. The decorator receives the inner instance and the container.
	 *
	 * @param string   $id        Service id.
	 * @param callable $decorator Decorator: fn( mixed $inner, Container $c ): mixed.
	 * @throws \OutOfBoundsException When the service is not registered.
	 */
	public function extend( string $id, callable $decorator ): void {
		if ( ! isset( $this->factories[ $id ] ) ) {
			throw new \OutOfBoundsException( sprintf( 'Service "%s" is not registered.', esc_html( $id ) ) );
		}
		$inner                  = $this->factories[ $id ];
		$this->factories[ $id ] = static fn( Container $c ): mixed => $decorator( $inner( $c ), $c );
		unset( $this->instances[ $id ] );
	}
}