public function history(\Illuminate\Http\Request $request, $days = 30)
 {
     for ($i = 0; $i < $days; $i++) {
         $day = Carbon::now()->subDays($i);
         $service_provider = get_called_class();
         $data = $service_provider::getSourceDataByDate($day->format('j.n.Y'));
         foreach ($data as $code => $course) {
             $currency = Currency::where('code', $code)->first();
             if ($currency) {
                 CurrenciesHistory::create(['currency_id' => $currency->id, 'rate' => $course['rate'], 'created_at' => $day->format('Y-m-d H:i:s')]);
             }
         }
     }
     if ($request->ajax()) {
         return ['success' => true];
     }
     return redirect()->back()->withMessage();
 }
 /**
  * {@inheritDoc}
  */
 public function updated(Currency $currency)
 {
     // Currency rate changed
     CurrenciesHistory::create(['rate' => $currency->unit, 'currency_id' => $currency->id]);
     $this->flushCache($currency);
 }