nordsoftware/lumen-core

<?php

namespace Nord\Lumen\Core\Middleware;

use Closure;
use Illuminate\Cache\RateLimiter;
use Illuminate\Http\Request;
use Nord\Lumen\Core\Traits\CreatesHttpResponses;
use Symfony\Component\HttpFoundation\Response;

class ThrottleRequests
{
    use CreatesHttpResponses;

    /**
     * The rate limiter instance.
     *
     * @var RateLimiter
     */
    private $rateLimiter;

    /**
     * Create a new request throttler.
     *
     * @param RateLimiter $rateLimiter
     */
    public function __construct(RateLimiter $rateLimiter)
    {
        $this->rateLimiter = $rateLimiter;
    }

    /**
     * Handle an incoming request.
     *
     * @param Request $request
     * @param Closure $next
     * @param int     $maxAttempts
     * @param int     $decayMinutes
     *
     * @return mixed
     */
    public function handle(Request $request, Closure $next, $maxAttempts = 60, $decayMinutes = 1)
    {
        $key = $this->resolveRequestSignature($request);

        if ($this->rateLimiter->tooManyAttempts($key, $maxAttempts, $decayMinutes)) {
            return $this->buildResponse($key, $maxAttempts);
        }

        $this->rateLimiter->hit($key, $decayMinutes);

        $response = $next($request);

        return $this->addHeaders(
            $response, $maxAttempts,
            $this->calculateRemainingAttempts($key, $maxAttempts)
        );
    }

    /**
     * Resolve request signature.
     *
     * @param Request $request
     *
     * @return string
     */
    protected function resolveRequestSignature($request)
    {
        return sha1(
            $request->method() .
            '|' . $request->server('SERVER_NAME') .
            '|' . $request->path() .
            '|' . $request->ip()
        );
    }

    /**
     * Create a 'too many attempts' response.
     *
     * @param string $key
     * @param int    $maxAttempts
     *
     * @return Response
     */
    protected function buildResponse($key, $maxAttempts)
    {
        $response = $this->errorResponse('Too Many Requests', [], 429);

        $retryAfter = $this->rateLimiter->availableIn($key);

        return $this->addHeaders(
            $response, $maxAttempts,
            $this->calculateRemainingAttempts($key, $maxAttempts, $retryAfter),
            $retryAfter
        );
    }

    /**
     * Add the limit header information to the given response.
     *
     * @param Response $response
     * @param int      $maxAttempts
     * @param int      $remainingAttempts
     * @param int|null $retryAfter
     *
     * @return Response
     */
    protected function addHeaders(Response $response, $maxAttempts, $remainingAttempts, $retryAfter = null)
    {
        $headers = [
            'X-RateLimit-Limit' => $maxAttempts,
            'X-RateLimit-Remaining' => $remainingAttempts,
        ];

        if (!is_null($retryAfter)) {
            $headers['Retry-After'] = $retryAfter;
        }

        $response->headers->add($headers);

        return $response;
    }

    /**
     * Calculate the number of remaining attempts.
     *
     * @param string   $key
     * @param int      $maxAttempts
     * @param int|null $retryAfter
     *
     * @return int
     */
    protected function calculateRemainingAttempts($key, $maxAttempts, $retryAfter = null)
    {
        if (!is_null($retryAfter)) {
            return 0;
        }

        return $this->rateLimiter->retriesLeft($key, $maxAttempts);
    }
}