felixarntz/wp-site-identity

<?php
/**
 * WP_Site_Identity_Service_Container class
 *
 * @package WPSiteIdentity
 * @since 1.0.0
 */

/**
 * Plugin service container.
 *
 * @since 1.0.0
 */
final class WP_Site_Identity_Service_Container {

    /**
     * All service definitions part of the container.
     *
     * @since 1.0.0
     * @var array
     */
    protected $definitions = array();

    /**
     * All service instances already created by the container.
     *
     * @since 1.0.0
     * @var array
     */
    protected $instances = array();

    /**
     * Gets a service.
     *
     * @since 1.0.0
     *
     * @param string $id Identifier of the service.
     * @return mixed Service instance.
     *
     * @throws WP_Site_Identity_Service_Not_Found_Exception Thrown when the service cannot be found.
     */
    public function get( $id ) {
        if ( ! isset( $this->instances[ $id ] ) ) {
            if ( ! isset( $this->definitions[ $id ] ) ) {
                /* translators: %s: service identifier */
                throw new WP_Site_Identity_Service_Not_Found_Exception( sprintf( __( 'The service with the identifier %s could not be found.', 'wp-site-identity' ), $id ) );
            }

            $reflected_class = new ReflectionClass( $this->definitions[ $id ]['class_name'] );

            $constructor = $reflected_class->getConstructor();
            if ( $constructor ) {
                $constructor_params = $this->definitions[ $id ]['constructor_params'];

                // Resolve service references.
                foreach ( $constructor_params as $index => $constructor_param ) {
                    if ( is_a( $constructor_param, 'WP_Site_Identity_Service_Reference' ) ) {
                        $constructor_params[ $index ] = $this->get( $constructor_param->get_id() );
                    }
                }

                $this->instances[ $id ] = $reflected_class->newInstanceArgs( $constructor_params );
            } else {
                $this->instances[ $id ] = $reflected_class->newInstance();
            }
        }

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

    /**
     * Checks whether a service can be retrieved.
     *
     * @since 1.0.0
     *
     * @param string $id Identifier of the service.
     * @return bool True if the service can be retrieved, false otherwise.
     */
    public function has( $id ) {
        return isset( $this->definitions[ $id ] );
    }

    /**
     * Registers a new service.
     *
     * @since 1.0.0
     *
     * @param string $id                 Identifier of the service.
     * @param string $class_name         Class name of the service.
     * @param array  $constructor_params Optional. Parameters to pass into the class constructor. Default empty array.
     *
     * @throws WP_Site_Identity_Service_Already_Registered_Exception Thrown when a service with the $id already exists.
     */
    public function register( $id, $class_name, $constructor_params = array() ) {
        if ( isset( $this->definitions[ $id ] ) ) {
            /* translators: %s: service identifier */
            throw new WP_Site_Identity_Service_Already_Registered_Exception( sprintf( __( 'The service with the identifier %s is already registered.', 'wp-site-identity' ), $id ) );
        }

        $this->definitions[ $id ] = array(
            'class_name'         => $class_name,
            'constructor_params' => $constructor_params,
        );
    }
}