/// <summary>
/// Close a position. If not all shares are used, return
/// a closed position. Modify position so that it can still be used
/// as an open position with the remaining shares.
/// If all shares are used, return null;
/// </summary>
/// <param name="position"></param>
/// <param name="stock"></param>
/// <param name="sharesToSell"></param>
/// <returns></returns>
public static Position ClosePosition(Position position, Stock stock, double sharesToSell)
{
position.CurrentPrice = stock.AdjustedClose;
if (Math.Abs(sharesToSell - position.Shares) < Portfolio.Epsilon)
{
// all shares used up, just close this position and returns null
// some bookkeeping
position.SoldDate = stock.Date;
position.Close = true;
return null;
}
double remainingShares = position.Shares - sharesToSell;
// change the position shares
position.Shares = remainingShares;
// now return a closed position with the shares sold
return new Position
{
// acquired date is the same
AcquiredDate = position.AcquiredDate,
Shares = sharesToSell,
// acquired price is also the same
AcquiredPrice = position.AcquiredPrice,
CurrentPrice = stock.AdjustedClose,
Close = true,
SoldDate = stock.Date,
Name = stock.Name,
Ticker = stock.Ticker
};
}
public void UpdatePortfolioAfterClosingPosition(Position position)
{
// pay TAXES
if (position.Gain > 0)
{
double gain = position.Gain;
// offset using capital loss
if (CapitalLoss > Epsilon)
{
// too much losses!
if (gain < CapitalLoss)
{
CapitalLoss -= gain;
gain = 0;
}
else
{
gain -= CapitalLoss;
CapitalLoss = 0;
}
}
// time to pay our taxes :(
Cash -= gain * TaxToPay(position);
}
else
{
CapitalLoss -= position.Gain;
}
}
public double TaxToPay(Position position)
{
if (NoTax)
{
return 0;
}
// let's find our income
int year = position.SoldDate.Year;
if (!IncomeAndTaxes.ContainsKey(year))
{
// not created yet so put in a yearly income
IncomeAndTaxes.Add(year, new IncomeAndTax(YearlyIncome, year));
}
// get the income
IncomeAndTax currentYear = IncomeAndTaxes[year];
// add the gain to the income if it's positive
if (position.Gain > 0)
{
currentYear.Income += position.Gain;
}
return IncomeAndTax.GetTaxRate(currentYear.Income, position.LongTerm);
}
/// <summary>
/// Opens a position
/// </summary>
/// <param name="stock"></param>
public static Position OpenPosition(Stock stock, double shares)
{
Position position = new Position
{
AcquiredDate = stock.Date,
Shares = shares,
AcquiredPrice = stock.AdjustedClose,
CurrentPrice = stock.AdjustedClose,
Name = stock.Name,
Ticker = stock.Ticker
};
return position;
}
