private bool IsLimitValueMonth(IncomeTaxThreshold currentValueIncomeTaxThreshold, TaxCalculationContext context)
{
var currentIncomesSum = context.TotalIncomes + context.CurrentIncome;
return(currentIncomesSum > currentValueIncomeTaxThreshold.ToAmount &&
context.TotalIncomes > currentValueIncomeTaxThreshold.FromAmount);
}
private decimal CalculateForBorderMonth(TaxCalculationContext context, IncomeTaxThreshold currentValueIncomeTaxThreshold, IncomeTaxThreshold nextThreshold)
{
decimal taxValue = (currentValueIncomeTaxThreshold.ToAmount - context.TotalIncomes) * currentValueIncomeTaxThreshold.Percentage;
var remainingValueForNextThreshold = ((context.TotalIncomes + context.CurrentIncome) - nextThreshold.FromAmount) * nextThreshold.Percentage;
return(taxValue + remainingValueForNextThreshold);
}
public decimal Calculate(TaxCalculationContext context)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
decimal taxValue = 0;
List <IncomeTaxThreshold> incomeTaxThresholds = GetIncomeTaxThreshold();
var currentValueIncomeTaxThreshold =
GetCurrentValueIncomeTaxThreshold(context, incomeTaxThresholds);
if (IsLimitValueMonth(currentValueIncomeTaxThreshold, context))
{
IncomeTaxThreshold nextThreshold = GetNextIncomeTaxThreshold(incomeTaxThresholds, currentValueIncomeTaxThreshold);
taxValue = CalculateForBorderMonth(context, currentValueIncomeTaxThreshold, nextThreshold);
}
else
{
taxValue = CalculateForFullMonth(currentValueIncomeTaxThreshold, context);
}
return(Decimal.Round(taxValue, 2));
}
private IncomeTaxThreshold GetNextIncomeTaxThreshold(List <IncomeTaxThreshold> incomeTaxThresholds,
IncomeTaxThreshold currentTaxThreshold)
{
return(incomeTaxThresholds.FirstOrDefault(x => x.ThresholdNumber == (currentTaxThreshold.ThresholdNumber + 1)));
}
private decimal CalculateForFullMonth(IncomeTaxThreshold currentValueIncomeTaxThreshold, TaxCalculationContext context)
{
return(context.CurrentIncome * currentValueIncomeTaxThreshold.Percentage);
}
private decimal GetTaxPercentage()
{
IncomeTaxThreshold incomeTaxThreshold = _taxPercentagesService.GetLinearRate() ?? throw new DomainException("Tax percentages not found");
return(incomeTaxThreshold.Percentage);
}
