blue-twilight/app/Providers/AppServiceProvider.php

<?php

namespace App\Providers;

use App\Album;
use App\Helpers\ConfigHelper;
use App\Helpers\ImageHelper;
use App\Helpers\ThemeHelper;
use App\Helpers\ValidationHelper;
use App\ModelObservers\AlbumObserver;
use Illuminate\Database\QueryException;
use Illuminate\Mail\Mailer;
use Illuminate\Pagination\LengthAwarePaginator;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Validator;
use Illuminate\Support\Facades\View;
use Illuminate\Support\ServiceProvider;

class AppServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot()
    {
        $themeHelper = new ThemeHelper();

        $this->app->singleton('image', function ($app)
        {
            return new ImageHelper();
        });
        $this->app->singleton('theme', function ($app) use ($themeHelper)
        {
            return $themeHelper;
        });
        $this->app->singleton('user_config', function ($app)
        {
            return new ConfigHelper();
        });

        Validator::extend('is_dir', (ValidationHelper::class . '@directoryExists'));
        Validator::extend('dir_empty', (ValidationHelper::class . '@isDirectoryEmpty'));
        Validator::extend('is_writeable', (ValidationHelper::class . '@isPathWriteable'));

        // Model observers
        Album::observe(AlbumObserver::class);

        // Configure our default pager
        LengthAwarePaginator::defaultView($themeHelper->viewName('partials.pager_links'));
    }

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