<?php
/**
 * Minimal service container.
 *
 * @package Consentfold
 */

declare(strict_types=1);

namespace Consentfold;

use LogicException;
use OutOfBoundsException;

/**
 * Lazy, shared-instance container. Each service is a factory invoked once, on first get().
 */
final class Container {

	/**
	 * Service factories keyed by id.
	 *
	 * @var array<string, callable(self): mixed>
	 */
	private array $factories = array();

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

	/**
	 * Ids currently being resolved, to detect circular dependencies.
	 *
	 * @var array<string, true>
	 */
	private array $resolving = array();

	/**
	 * Register a service factory.
	 *
	 * @param string               $id      Service id.
	 * @param callable(self):mixed $factory Receives the container, returns the service.
	 * @throws LogicException When the id is already registered.
	 */
	public function set( string $id, callable $factory ): void {
		if ( $this->has( $id ) ) {
			throw new LogicException( sprintf( 'Service "%s" is already registered.', $id ) ); // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped
		}

		$this->factories[ $id ] = $factory;
	}

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

	/**
	 * Resolve a service, building it on first use.
	 *
	 * @param string $id Service id.
	 * @return mixed
	 * @throws OutOfBoundsException When the id is not registered.
	 * @throws LogicException       When services depend on each other in a cycle.
	 */
	public function get( string $id ) {
		if ( array_key_exists( $id, $this->instances ) ) {
			return $this->instances[ $id ];
		}

		if ( ! $this->has( $id ) ) {
			throw new OutOfBoundsException( sprintf( 'Service "%s" is not registered.', $id ) ); // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped
		}

		if ( isset( $this->resolving[ $id ] ) ) {
			throw new LogicException( sprintf( 'Circular dependency while resolving "%s".', $id ) ); // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped
		}

		$this->resolving[ $id ] = true;
		try {
			$this->instances[ $id ] = ( $this->factories[ $id ] )( $this );
		} finally {
			unset( $this->resolving[ $id ] );
		}

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