/// <summary>
/// Given a set of cash and a desired price, get the amount of the cash
/// to meet the price (rounded up for safety)
/// </summary>
/// <param name="AvailableCash">The amount of cash avaliable.</param>
/// <param name="price">The price to meet (roughly)</param>
/// <returns>The appropriate cash for the price.</returns>
/// <exception cref="ArgumentNullException">If <paramref name="AvailableCash"/> is null.</exception>
/// <exception cref="ArgumentOutOfRangeException">If <paramref name="price"/> is less than or equal to 0.</exception>
public IProductAmountCollection ChangeForPrice(IProductAmountCollection AvailableCash, double price)
{
// ensure cash is not null.
if (AvailableCash is null)
{
throw new ArgumentNullException(nameof(AvailableCash));
}
// ensure that the price is greater than 0
if (price <= 0) // TODO, allow this to savely give change for 0. It's not that hard.
{
throw new ArgumentOutOfRangeException("Price must be greater than 0.");
}
// first, check that all available cash can meet the price.
var totalCash = AvailableCash.Sum(x => x.Item2 * ProductPrices.GetProductValue(x.Item1));
// If the total cash available is less than the price sought, return a copy of the available cash.
if (totalCash < price)
{
return(AvailableCash.Copy());
}
// since we have more than we need,
var result = new ProductAmountCollection();
// start from the best and start making change, highest to lowest value.
foreach (var coin in AvailableCash.OrderByDescending(x => ProductPrices.GetProductValue(x.Item1)))
{
// if none of that coin exist
if (coin.Item2 == 0)
{
// add it as zero
result.AddProducts(coin.Item1, 0);
// and skip to the next loop
continue;
}
// coin type
var curr = coin.Item1;
// coin value
var val = ProductPrices.GetProductValue(curr);
// if value is higher then remaining price.
if (val > price)
{
// add it as zero
result.AddProducts(curr, 0);
// and skip
continue;
}
// coin amount
var amt = coin.Item2;
// how many whole coins can fit into the price.
var count = Math.Floor(price / val);
// select cap coins at the available level.
count = Math.Min(count, amt);
// add to our change
result.AddProducts(curr, count);
// subtract the value we took out
price -= val * count;
// then go to the next coin.
}
// if there is a remainder
if (price > 0)
{
// find the smallest coin available
foreach (var coin in AvailableCash.OrderBy(x => ProductPrices.GetProductValue(x.Item1)))
{
// if we have any available
if (result.GetProductValue(coin.Item1) < AvailableCash.GetProductValue(coin.Item1))
{
// add one
result.AddProducts(coin.Item1, 1);
// and move on.
break;
// by logic, only one should be needed as we guaranteed have
// more value in coins then the requested price and the
// remainder should be smaller than the smallest coin.
}
}
}
// return the change.
return(result);
}
public IProductAmountCollection BuyGood(IProductAmountCollection cash,
IProduct good, double amount, IMarket market)
{
// Sanity check for nulls.
if (cash is null)
{
throw new ArgumentNullException(nameof(cash));
}
if (good is null)
{
throw new ArgumentNullException(nameof(good));
}
if (market is null)
{
throw new ArgumentNullException(nameof(market));
}
if (amount <= 0)
{
throw new ArgumentOutOfRangeException(nameof(amount));
}
// The collection we're returning.
var result = new ProductAmountCollection();
// get how much to buy, what's available, or what's desired.
var available = Math.Min(amount, ForSale.GetProductValue(good));
// get the price of that good
var totalPrice = GetPrice(good, market.GetPrice(good)) * available;
// get the cash needed for the goods
var money = market.ChangeForPrice(cash, totalPrice);
// get our available money total
var totalMoney = money.Sum(x => market.GetPrice(x.Item1, x.Item2));
// if the money is enough, just buy outright
if (totalMoney >= totalPrice)
{
// Add what they're buying.
result.AddProducts(good, available);
// remove what they spent
result.AddProducts(money.Multiply(-1));
}
else if (!good.Fractional && totalMoney < market.GetPrice(good))
{// If the total money is not enough for a single unit, and the good can't be divided
// we can't actually buy anything, so just return an empty transaction
return(new ProductAmountCollection());
}
else // if it's not enough
{
// get the buyable units of the good
double buyableUnits = 0;
// if we can buy fractionally
if (good.Fractional)
{
// just do the math straight.
buyableUnits = totalMoney / market.GetPrice(good);
}
else // if we can't
{
// take what we can and round down, seller should always make more than the buyer here.
buyableUnits = Math.Floor(totalMoney / market.GetPrice(good));
}
// if we can buy any units
if (buyableUnits > 0)
{
// buy them add the units to the results
result.AddProducts(good, buyableUnits);
// subtract the cash.
result.AddProducts(money.Multiply(-1));
}
}
// Get change, if any.
var change = totalMoney - market.GetPrice(good) * result.GetProductValue(good);
// get the change, if any
IProductAmountCollection buyersChange = new ProductAmountCollection();
// if change is greater than 0.
if (change > 0) // Make said change.
{
buyersChange = market.ChangeForPrice(GetCash(market.AcceptedCurrencies), change);
}
// add back the buyer's change
result.AddProducts(buyersChange);
// TODO, maybe add check to see if the seller shortchanged the buyer.
// complete the transaction for the seller, and subtract the result.
CompleteTransaction(result.Multiply(-1));
// we're done, return the change in the buyer's goods.
return(result);
}
/// <summary>
/// Buys good from the market.
/// </summary>
/// <param name="buyer">The one buying the good.</param>
/// <param name="good">The good they are trying to buy.</param>
/// <param name="amount">How much they are trying to buy.</param>
/// <returns>The Receipt of purchases</returns>
public IProductAmountCollection BuyGoodsFromMarket(IPopulationGroup buyer,
IProduct good, double amount)
{
if (buyer is null)
{
throw new ArgumentNullException(nameof(buyer));
}
if (good is null)
{
throw new ArgumentNullException(nameof(good));
}
if (amount <= 0)
{
throw new ArgumentOutOfRangeException(nameof(amount));
}
// The result of the purchases.
IProductAmountCollection result = new ProductAmountCollection();
// First buy from local merchants, they only accept cash.
result = Populous.Merchants
.BuyGood(buyer.GetCash(AcceptedCurrencies), good, amount, this);
// see how much was bought.
double remainder = 0;
// if any was bought, update what we are seeking.
if (result.Contains(good))
{
remainder = amount - result.GetProductValue(good);
// and complete the transaction
buyer.CompleteTransaction(result);
}
// if no remainder, return
if (remainder <= 0)
{
return(result);
}
// Then buy from everyone else via both cash and barter.
foreach (var seller in Populous.GetPopsSellingProduct(good))
{
// If someone is selling the good, buy or barter with them.
var reciept = BuyGoods(buyer, good, remainder, seller);
// if something was bought
if (reciept.Count() > 0)
{
// remove it from the remainder
remainder -= reciept.GetProductValue(good);
// add it to our result
result.AddProducts(reciept);
}
// if nothing remains, we're done.
if (remainder <= 0)
{
return(result);
}
}
// Finish buy going to the travelling merchants, if all else fails.
foreach (var travSeller in TravellingMerchantsSelling(good))
{
var reciept = travSeller.BuyGood(buyer.GetCash(AcceptedCurrencies), good, remainder, this);
// if something was bought
if (reciept.Count() > 0)
{
// remove it from remainder
remainder -= reciept.GetProductValue(good);
// Complete the transaction for the buyer
buyer.CompleteTransaction(reciept);
// add it to the result
result.AddProducts(reciept);
}
// if nothing remains, return
if (remainder <= 0)
{
return(result);
}
}
// return the ultimate receipt.
return(result);
}
