pixelfed/app/Providers/AppServiceProvider.php

<?php

namespace App\Providers;

use App\User;
use Auth, Horizon;
use App\Observers\UserObserver;
use Illuminate\Support\Facades\Blade;
use Illuminate\Support\ServiceProvider;

class AppServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot()
    {
        User::observe(UserObserver::class);

        Horizon::auth(function ($request) {
            return Auth::check() && $request->user()->is_admin;
        });

        Blade::directive('prettyNumber', function($expression) {
            $num = $expression;
            $abbrevs = array(12 => "T", 9 => "B", 6 => "M", 3 => "K", 0 => "");
            foreach($abbrevs as $exponent => $abbrev) {
                if($expression >= pow(10, $exponent)) {
                  $display_num = $expression / pow(10, $exponent);
                  $num = number_format($display_num,0) . $abbrev;
                  return "<?php echo '$num'; ?>";
                }
            }
            return "<?php echo $num; ?>";
        });

        Blade::directive('prettySize', function($expression) {

            $size = intval($expression);
            $precision = 0;
            $short = true;
            $units = $short ?
                ['B','k','M','G','T','P','E','Z','Y'] :
                ['B','kB','MB','GB','TB','PB','EB','ZB','YB'];
            for($i = 0; ($size / 1024) > 0.9; $i++, $size /= 1024) {}
            $res = round($size, $precision).$units[$i];
            return "<?php echo '$res'; ?>";
        });
    }

    /**
     * Register any application services.
     *
     * @return void
     */
    public function register()
    {
        //
    }
}