public async Task <List <TransactionsDTO> > GetTransactionsBySKUinEuro(string SKU)
{
//I'm understanding that this method will be called after getting rates and transactions.
//That's the reason why I'm reading first from DB, to avoid make 2 requests to the URL that provides data.
try
{
//Get rates, first from DB, if there is not data, go to URL
var rates = _ratesRepository.FindAll().Select(x => DTOMapper.Rate_To_RateDTO(x)).ToList();
if (!rates.Any())
{
rates = await GetRates();
}
var euroRates = GetToEuroRates(rates.ToList());
//Get Transactions filtering by SKU, first from DB, if there is not data, go to URL
var transactions = _transactionsRepository.FindAll(x => x.SKU == SKU).Select(x => DTOMapper.Transaction_To_TransactionDTO(x)).ToList();
if (!transactions.Any())
{
transactions = await GetTransactions();
transactions = transactions.ToList().Where(x => x.SKU == SKU).ToList() ?? new List <TransactionsDTO>();
}
if (!transactions.Any())
{
//TODO: Add constants or resources file to avoid hardcoded strings
LoggerHelper.LogError("There are not transactions for the required SKU");
}
else
{
foreach (var trans in transactions.Where(x => x.Currency != "EUR"))
{
var rate = euroRates.FirstOrDefault(x => x.From == trans.Currency);
if (rate != null)
{
trans.Amount = RounderHelper.RoundToBankersRounding(trans.Amount * rate.Rate);
trans.Currency = "EUR";
}
}
}
return(transactions.ToList());
}
catch (Exception ex)
{
LoggerHelper.LogError(ex.ToString());
return(new List <TransactionsDTO>());
}
}
public async Task <JsonResult> Get(string SKU)
{
var transactionsInEuro = await TransactionsWorker.GetTransactionsBySKUinEuro(SKU);
List <object> result = new List <object>();
if (transactionsInEuro.Any())
{
result.Add(transactionsInEuro);
result.Add(new
{
SKU = SKU,
Total_Amount = RounderHelper.RoundToBankersRounding(transactionsInEuro.Sum(x => x.Amount))
});
}
else
{
result.Add(new { Message = "There are not transactions for the requested SKU!" });
}
return(new JsonResult(result));
}
private List <RatesDTO> GetToEuroRates(List <RatesDTO> lRates)
{
List <RatesDTO> conversedRates = new List <RatesDTO>();
try
{
List <string> currencies = new List <string>();
//Add to a list the different currencies
currencies.AddRange(lRates.Select(x => x.From).Distinct());
currencies.AddRange(lRates.Select(x => x.To).Distinct());
currencies = currencies.Where(x => x != "EUR").Distinct().ToList();
//Find direct conversions that we already have
foreach (var currency in currencies)
{
conversedRates.AddRange(lRates.Where(x => x.From == currency && x.To == "EUR"));
}
//Add to a new list the pending currencies which still doesn't have a conversion to EUR
var pendingCurrencies = currencies.Except(conversedRates.Select(x => x.From)).ToList();
//Simple (and dirty) control to avoid possible infinite loop if can't find conversions
var maxRetry = 10;
var counter = 0;
while (pendingCurrencies.Any() && counter < maxRetry)
{
counter++;
foreach (var currency in pendingCurrencies)
{
//find a indirect conversion
var currencyConversions = lRates.Where(x => x.From == currency).ToList();
var indirectConversion = new RatesDTO();
RatesDTO usedRate = null;
foreach (var item in currencyConversions)
{
if ((indirectConversion = conversedRates.FirstOrDefault(x => x.From == item.To)) != null)
{
usedRate = item;
break;
}
}
//Use the indirect conversion to calculate the EUR conversion
if (usedRate != null)
{
conversedRates.Add(new RatesDTO
{
From = currency,
To = "EUR",
Rate = RounderHelper.RoundToBankersRounding(usedRate.Rate * indirectConversion.Rate)
});
pendingCurrencies = pendingCurrencies.Except(conversedRates.Select(x => x.From)).ToList();
}
}
}
}
catch (Exception ex)
{
LoggerHelper.LogError(ex.ToString());
}
return(conversedRates);
}