public async Task <CurrencyPair> GetAverageCurencyRateForDates(string firstCurrency, string secondCurrency,
DateTime startDate, DateTime endDate)
{
CheckCurrences(firstCurrency, secondCurrency);
var resultsCollection = await _apiProvider.GetCurrencyByDateRange(firstCurrency, secondCurrency, startDate, endDate);
float average = resultsCollection.Select(x => x.ExchangeRate).Average();
return(new CurrencyPair(firstCurrency, secondCurrency, average, startDate, endDate));
}
