Higher-Order application building

application.php

<?php declare(strict_types=1);

namespace proj\http;

interface ApplicationInterface {
    public function run();
    
    public function use(callable $aMiddleware);
    
    public function respondTo(string $anHttpMethod, string $aUriPath, callable $aResponder);
}

middleware.php

<?php declare(strict_types=1);

namespace proj\api\middleware;

use proj\html\TemplateManagerInterface as TemplateManager;
use const proj\http\STATUS_401;

use Psr\Http\Message\ServerRequestInterface as Request;
use Psr\Http\Message\ResponseInterface as Response;

// $app->use(authenticate($config->get("api-key")));
function authenticate(string $anApiKey) : callable
{
    return function (Request $aRequest, Response $aResponse, callable $aNextAction)
        use ($anApiKey) : Response
    {
        if ($aRequest->getHeader("x-api-key") !== $anApiKey) {
            return $aResponse->withStatusCode(STATUS_401);
        }
        return $aNextAction($aRequest, $aResponse);
    };
}

// $app->use(format_as_json());
function format_as_json() : callable
{
    return function (Request $aRequest, Response $aResponse, callable $aNextAction) : Response
    {
        if ($aRequest->getHeader("Content-Type") === "application/json") {
            $body = $aResponse->getBody();
            $aResponse->getBody()->write(json_encode($body));
        }
        return $aNextAction($aRequest, $aResponse);
    };
}

// $app->use(format_as_html($services->get("template-manager")));
function format_as_html(TemplateManager $aTemplateManager) : callable
{
    return function (Request $aRequest, Response $aResponse, callable $aNextAction)
        use ($aTemplateManager) : Response
    {
        if ($aRequest->getHeader("Content-Type") === "text/html") {
            $path      = $aRequest->getUri()->getPath();
            $renderer  = $aTemplateManager->findForUriPath($path);
            $aResponse = $renderer->render($aResponse));
        }
        return $aNextAction($aRequest, $aResponse);
    };
}

route.php

<?php declare(strict_types=1);

namespace proj\api\route;

use proj\domain\user\ServiceInterface as UserService;
use const proj\domain\user\STATUS_ENABLED;
use const proj\domain\user\ORDER_BY_LASTNAME_ASC;
use proj\helper\PaginatorInterface as Paginator;

use Psr\Http\Message\ServerRequestInterface as Request;
use Psr\Http\Message\ResponseInterface as Response;

// $app->respondTo("GET", "/users", list_users(
//     $services->get("user-service"),
//     $services->get("result-paginator"),
//     $config->get("result-limit")
// ));
function list_users(UserService $aUserService, Paginator $aPaginator, int $aResultLimit) : callable
{
    return function (Request $aRequest, Response $aResponse, callable $aNextAction)
        use ($aUserService, $aPaginator, $aResultLimit) : Response
    {
        $status  = $aRequest->getAttribute("status", STATUS_ENABLED);
        $orderBy = $aRequest->getAttribute("order_by", ORDER_BY_LASTNAME_ASC);
        $users   = $aUserService->listAllWithStatus($status, $orderBy);
        
        $page    = $aRequest->getAttribute("page", 1);
        $limit   = $aRequest->getAttribute("limit", $aResultLimit);
        $results = $aPaginator->paginate($users, $page, $limit);
        
        $aResponse->getBody()->write($results);
        return $aNextAction(null, $aResponse);
    };
}

// $app->respondTo("GET", "/users/{id}", get_user($services->get("user-service")));
function get_user(UserService $aUserService) : callable
{
    return function (Request $aRequest, Response $aResponse, callable $aNextAction)
        use ($aUserService) : Response
    {
        $id   = $aRequest->getAttribute("id");
        $user = $aUserService->find($id);
        $aResponse->getBody()->write($user);
        return $aNextAction(null, $aResponse);
    };
}