Slick\Http\Server\MiddlewareStack

Complexity

Total Complexity

10

Size/Duplication

Total Lines	88
Duplicated Lines	0 %

Coupling/Cohesion

Components	1
Dependencies	4

Importance

Changes

0

4 Methods

Rating	Name	Duplication	Size	Complexity
A	__construct()	0	6	2
A	push()	0	14	3
A	process()	0	5	1
B	resolve()	0	24	4

<?php

/**
 * This file is part of slick/http
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Slick\Http\Server;

use Interop\Http\Server\MiddlewareInterface;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Slick\Http\Server\Exception\InvalidArgumentException;
use Slick\Http\Server\Exception\UnexpectedValueException;
use Slick\Http\Server\Middleware\CallableMiddleware;

/**
 * MiddlewareStack
 *
 * @package Slick\Http\Server
 */
class MiddlewareStack
{
    /**
     * @var array|MiddlewareInterface[]
     */
    private $middlewareStack = [];

    /**
     * Creates a Middleware Stack
     *
     * @param MiddlewareInterface[]|callable[] $middlewareStack
     */
    public function __construct(array $middlewareStack)
    {
        foreach ($middlewareStack as $middleware) {
            $this->push($middleware);
        }
    }

    /**
     * Pushes a middleware to the stack
     *
     * @param MiddlewareInterface|callable $middleware
     *
     * @return MiddlewareStack
     */
    public function push($middleware)
    {
        if (
            ! $middleware instanceof MiddlewareInterface &&
            ! is_callable($middleware)
        ) {
            throw new InvalidArgumentException(
                "Middleware stack accepts only MiddlewareInterface object or callable"
            );
        }

        array_push($this->middlewareStack, $middleware);
        return $this;
    }

    /**
     * Processes all the middleware stack
     *
     * @param ServerRequestInterface $request
     *
     * @return \Psr\Http\Message\ResponseInterface
     */
    public function process(ServerRequestInterface $request)
    {
        $handler = $this->resolve(0);
        return $handler->handle($request);
    }

    /**
     * Creates a request handler for middleware at the position defined by $index
     *
     * @param int $index
     *
     * @return RequestHandler
     *
     * @throws UnexpectedValueException If the return form a middleware is not a ResponseInterface
     */
    private function resolve($index)
    {
        return new RequestHandler(function(ServerRequestInterface $request) use ($index) {

            $middleware = isset($this->middlewareStack[$index])
                ? $this->middlewareStack[$index]
                : new CallableMiddleware(function () {});

            if ($middleware instanceof \Closure) {
                $middleware = new CallableMiddleware($middleware);
            }

            $response = $middleware->process($request, $this->resolve($index + 1));

            if (!($response instanceof ResponseInterface)) {
                throw new UnexpectedValueException(
                    sprintf('The middleware must return an instance of %s', ResponseInterface::class)
                );
            }

            return $response;
        });

    }
}