public void GetCurrencyExchangeRatesAsync_GetsExchangeRatesForWorkDays()
{
//Arrange
var dateFrom = DateTime.Parse("2020-05-11"); //Monday
var dateTo = DateTime.Parse("2020-05-15"); //Friday
var currencyFrom = "USD";
var currencyTo = "EUR";
//Act
var result = _currencyRatesRetriver.GetCurrencyExchangeRatesAsync(currencyFrom, currencyTo, dateFrom, dateTo).Result;
//Assert
Assert.AreEqual(5, result.Count);
Assert.IsTrue(result.TrueForAll(x => x.Value > 0));
for (int i = 0; i < 5; i++)
{
Assert.IsTrue(result.Any(x => x.Date == dateFrom.AddDays(i)));
}
}
public async Task <List <CurrencyExchangeRate> > GetCurrencyExchangeRatesAsync(Dictionary <string, string> currencyCodes, DateTime from, DateTime to)
{
var result = new List <CurrencyExchangeRate>();
foreach (var currencyCode in currencyCodes)
{
List <CurrencyExchangeRate> currencyRates;
//chceck if data is available in db otherwise ask external api
if (await _currencyRepository.IsDataAvailable(currencyCode.Key, currencyCode.Value, from, to))
{
currencyRates = await _currencyRepository.GetAsync(currencyCode.Key, currencyCode.Value, from, to);
}
else
{
currencyRates = await _currencyRatesRetriver.GetCurrencyExchangeRatesAsync(currencyCode.Key, currencyCode.Value, from, to);
//resolve missing days
var requiredDates = Enumerable.Range(0, 1 + to.Subtract(from).Days)
.Select(offset => from.AddDays(offset))
.ToArray();
var missingDates = requiredDates.Where(x => !currencyRates.Any(y => y.Date == x));
foreach (var missingDate in missingDates.OrderBy(x => x.Date))
{
var previousRate = currencyRates.FirstOrDefault(x => x.Date == missingDate.Date.AddDays(-1));
if (previousRate != null)
{
currencyRates.Add(new CurrencyExchangeRate()
{
CurrencyFrom = previousRate.CurrencyFrom,
CurrrencyTo = previousRate.CurrrencyTo,
Date = missingDate,
Value = previousRate.Value,
IsFromPreviousDay = true
});
}
else
{
var offset = 30;
var pastRates = await _currencyRatesRetriver.GetCurrencyExchangeRatesAsync(currencyCode.Key, currencyCode.Value, missingDate.Date.AddDays(-1 * offset), missingDate);
for (int i = 1; i < offset; i++)
{
var found = pastRates.FirstOrDefault(x => x.Date == missingDate.AddDays(-1 * i));
if (found != null)
{
found.IsFromPreviousDay = true;
found.Date = missingDate;
currencyRates.Add(found);
break;
}
}
}
}
await _currencyRepository.StoreAsync(currencyRates);
}
result.AddRange(currencyRates.OrderBy(x => x.Date));
}
return(result);
}