Federation.php

<?php

namespace App\GraphQL\Queries;

use App\GraphQL\SchemaPrinter;
use GraphQL\Type\Definition\ResolveInfo;
use Nuwave\Lighthouse\GraphQL;
use Nuwave\Lighthouse\Support\Contracts\GraphQLContext;

/**
 * Class Federation
 *
 * @package App\GraphQL\Queries
 */
class Federation
{
    /**
     * @var GraphQL
     */
    protected $graphQL;

    /**
     * Federation constructor.
     *
     * @param \Nuwave\Lighthouse\GraphQL $graphQL
     */
    public function __construct(GraphQL $graphQL)
    {
        $this->graphQL = $graphQL;
    }

    /**
     * Return a value for the field.
     *
     * @param  null                                                $rootValue   Usually contains the result returned from the parent field. In this case, it is always `null`.
     * @param  mixed[]                                             $args        The arguments that were passed into the field.
     * @param  \Nuwave\Lighthouse\Support\Contracts\GraphQLContext $context     Arbitrary data that is shared between all fields of a single query.
     * @param  \GraphQL\Type\Definition\ResolveInfo                $resolveInfo Information about the query itself, such as the execution state, the field name, path to the field from the root, and more.
     *
     * @return mixed
     */
    public function __invoke($rootValue, array $args, GraphQLContext $context, ResolveInfo $resolveInfo)
    {
        switch ($resolveInfo->fieldName) {
            case '_service':
                return $this->service($rootValue, $args, $context, $resolveInfo);
            case '_entities':
                return $this->entities($rootValue, $args, $context, $resolveInfo);
            default:
                // no default for now
        }
    }

    /**
     * @param                $rootValue
     * @param array          $args
     * @param GraphQLContext $context
     * @param ResolveInfo    $resolveInfo
     *
     * @return array
     */
    protected function entities($rootValue, array $args, GraphQLContext $context, ResolveInfo $resolveInfo)
    {
        // TODO to be implemented (resolve reference)
        return [];
    }

    /**
     * @param                $rootValue
     * @param array          $args
     * @param GraphQLContext $context
     * @param ResolveInfo    $resolveInfo
     *
     * @return array
     */
    protected function service($rootValue, array $args, GraphQLContext $context, ResolveInfo $resolveInfo)
    {
        $schema = $this->graphQL->prepSchema();
        $newSchema = SchemaPrinter::printFederatedSchema(
            $schema,
            ['commentDescriptions' => false, 'federated' => true]
        );

        return ['sdl' => $newSchema];
    }
}