Verifying access to channel

Centrifuge.php

<?php

namespace App\Http\Controllers\Admin\API;

use App\Http\Controllers\Controller;
use App\Models\Channel;
use Illuminate\Http\Request;

class Centrifuge extends Controller
{
    /**
     * Check for access to the channel for authorized user
     *
     * @param \Illuminate\Http\Request $request
     * @return \Illuminate\Contracts\Routing\ResponseFactory|\Illuminate\Http\JsonResponse|\Symfony\Component\HttpFoundation\Response
     */
    public function postAuth(Request $request)
    {
        // On request is sent cookies
        // Checking authorization
        if (auth()->check()) {
            $client = $request->get('client');
            $channels = $request->get('channels');

            // If $channels isn't array make it
            $channels = is_array($channels) ? $channels : [$channels];

            // Getting the user ID
            $userId = auth()->user()->id;

            $response = [];

            // Receiving channels with users who can subscribe to the channel
            $channelModels = Channel::with('users')->whereIn('name', $channels)->get();

            foreach ($channels as $channel) {
                // Getting key array, which matches the channel name requested
                $key = $channelModels->search(function ($item, $key) use ($channel) {
                    return $item->name == $channel;
                });

                // If the key is false, so the requested channel does not exist
                if ($key !== false) {
                    $channelModel = $channelModels[$key];

                    // Info currently empty
                    $info = json_encode([]);

                    // Check for access to the channel from user
                    if ($channelModel->userHasAccess($userId)) {
                        // Result positive, generating signature
                        $response[$channel] = [
                            'sign' => $this->generateChannelSign($client, $channel, $info),
                            'info' => $info,
                        ];
                    } else {
                        // Access denied
                        $response[$channel] = [
                            'status' => 403,
                        ];
                    }
                } else {
                    // Channel not found
                    $response[$channel] = [
                        'status' => 404,
                    ];
                }

            }

            return response()->json($response);

        } else {
            return response('Unauthorized', 401);
        }
    }

    /**
     * @param string $client
     * @param string $channel
     * @param string $info
     * @return string
     */
    private function generateChannelSign($client, $channel, $info = '')
    {
        $ctx = hash_init('sha256', HASH_HMAC, config('broadcasting.connections.centrifuge.projectSecret'));
        hash_update($ctx, (string) $client);
        hash_update($ctx, (string) $channel);
        hash_update($ctx, (string) $info);

        return hash_final($ctx);
    }
}