Sitemap Middleware for Laravel

Sitemap.php

<?php

/**
 * This file is orginzed from @FDisk from StackOverflow
 * @see https://stackoverflow.com/a/28608156/8681141
 */

namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Request;
use Illuminate\Contracts\Auth\Guard;
use Illuminate\Support\Carbon;
use Illuminate\Support\Facades\Cache;

class Sitemap
{
    const TTL = 86400; // 1 day
    const KEY_NAME = 'app_sitemap';

    protected $guard;

    /**
     * @param Guard $guard
     */
    public function __construct(Guard $guard)
    {
        $this->guard = $guard;
    }

    /**
     * @param Request $request
     * @param Closure $next
     * @return mixed|void
     */
    public function handle(Request $request, Closure $next)
    {
        if (
            Cache::has(self::KEY_NAME)
            $request->is('sitemap') ||
            $request->fullUrl() === '/' ||
            !$this->guard->guest()
        ) {
            return $next($request);
        }

        // update sitemap
        $sitemap = Cache::get(self::KEY_NAME, []);
        $changeFreq = 'always';
        if (!empty($sitemap[$request->fullUrl()]['added'])) {
            $aDateDiff = Carbon::createFromTimestamp($sitemap[$request->fullUrl()]['added'])->diff(Carbon::now());
            if ($aDateDiff->y > 0) {
                $changeFreq = 'yearly';
            } elseif ($aDateDiff->m > 0) {
                $changeFreq = 'monthly';
            } elseif ($aDateDiff->d > 6) {
                $changeFreq = 'weekly';
            } elseif ($aDateDiff->d > 0 && $aDateDiff->d < 7) {
                $changeFreq = 'daily';
            } elseif ($aDateDiff->h > 0) {
                $changeFreq = 'hourly';
            } else {
                $changeFreq = 'always';
            }
        }

        $sitemap[$request->fullUrl()] = [
            'added' => time(),
            'lastmod' => Carbon::now()->toIso8601String(),
            'priority' => 1 - substr_count($request->getPathInfo(), '/') / 10,
            'changeFreq' => $changeFreq
        ];
        Cache::put(self::KEY_NAME, $sitemap, self::TTL);

        return $next($request);
    }
}