public VendingMachine(IDispenseProduct dispenser)
{
_dispenser = dispenser;
_productStock = _productCatalog.Keys.ToDictionary(k => k, s => 0);
_coinStock = new CoinBag(_weightToValueMap);
_currentMessage = GetDefaultMessage();
}
private void VerifyCoinBagsAcceptSameTypes(CoinBag otherBag)
{
if (!_coinQuantities.Keys.OrderBy(x => x).SequenceEqual(otherBag._coinQuantities.Keys.OrderBy(x => x)))
{
throw new InvalidOperationException("these bags map to different coin types");
}
}
public CoinBag Without(CoinBag otherBag)
{
VerifyCoinBagsAcceptSameTypes(otherBag);
var amounts = _coinQuantities.ToDictionary(x => x.Key, x => Math.Max(x.Value - otherBag._coinQuantities[x.Key], 0));
return(new CoinBag(_valueMap, amounts));
}
public CoinBag Merge(CoinBag otherBag)
{
VerifyCoinBagsAcceptSameTypes(otherBag);
var amounts = _coinQuantities.ToDictionary(x => x.Key, x => x.Value + otherBag._coinQuantities[x.Key]);
return(new CoinBag(_valueMap, amounts));
}
public void SelectProduct(string productCode)
{
productCode = SanitizeProductCode(productCode); //Postel's Law ;-)
if (!_productCatalog.ContainsKey(productCode))
{
return;
}
if (_productStock[productCode] <= 0)
{
_currentMessage = "SOLD OUT";
return;
}
var productPrice = _productCatalog[productCode];
_currentMessage = string.Format("PRICE {0:C}", productPrice);
var currentAmount = GetCurrentAmount();
if (currentAmount < productPrice)
{
return;
}
var changeDue = currentAmount - productPrice;
var coinStockAndInserted = _coinStock
.WithCoins(_coinsInserted);
if (!coinStockAndInserted.CanMakeChange(changeDue))
{
_currentMessage = "EXACT CHANGE ONLY";
return;
}
var coinsToReturn =
coinStockAndInserted
.MakeChange(changeDue);
_coinStock = coinStockAndInserted.Without(coinsToReturn);
_coinsInserted.Clear();
_currentMessage = "THANK YOU";
_dispenser.DispenseProduct(productCode);
_coinReturn.AddRange(coinsToReturn.ToCoins());
}
public void StockCoins(IDictionary <double, int> coinQuantities)
{
_coinStock = new CoinBag(_weightToValueMap, coinQuantities);
_currentMessage = GetDefaultMessage();
}