wikimedia/mediawiki-extensions-Wikibase

<?php

declare( strict_types=1 );

namespace Wikibase\Lib;

use LogicException;
use Wikimedia\Assert\Assert;

/**
 * @license GPL-2.0-or-later
 */
class ServiceBySourceAndTypeDispatcher {

    /** @var array[] */
    private $callbacks;

    /**
     * Map of entity source names and types to services that were created by the respective callback
     * @var array[]
     */
    private $services;

    /** @var string */
    private $serviceType;

    /**
     * @param string $type type of the dispatched services, i.e. type of the return value of the callbacks
     * @param array[][] $callbacks map of entity source names and types to callbacks creating the service to be used
     */
    public function __construct( string $type, array $callbacks ) {
        Assert::parameterElementType( 'array', $callbacks, '$callbacks' );
        //TODO: we don't check that the array is a 2D array of callables only keyed by string.
        Assert::parameterKeyType( 'string', $callbacks, '$callbacks' );
        if ( count( $callbacks ) === 0 ) {
            throw new LogicException( 'Callback array cannot be empty' );
        }

        $this->callbacks = $callbacks;
        $this->serviceType = $type;
    }

    private function createService( string $sourceName, string $entityType, array $args = [] ) {
        if ( isset( $this->callbacks[$sourceName][$entityType] ) ) {
            $this->services[$sourceName][$entityType] = $this->callbacks[$sourceName][$entityType]( ...$args );

            Assert::postcondition(
                $this->services[$sourceName][$entityType] instanceof $this->serviceType,
                "callback must return an instance of $this->serviceType"
            );

            return $this->services[$sourceName][$entityType];
        }
        throw new LogicException(
            'Unable to find ' . $this->serviceType . ' Service callback for Entity Type ' . $entityType . ' for Source ' . $sourceName
        );
    }

    public function getServiceForSourceAndType( string $sourceName, string $entityType, array $callbackArgs = [] ) {
        return $this->services[$sourceName][$entityType] ?? $this->createService( $sourceName, $entityType, $callbackArgs );
    }

}