Economy Interface Draft

gistfile1.java

/**
 * Rough draft of economy interface, and questions.
 * 
 * Use case:  Plugin (Consumer) wants to allow players to buy and sell items from a chest.  Plugin (Provider) offers economy/currency
 * to do so.  The Consumer will need to allow the player to setup the chest to sell the items.  This will require an account linked
 * to the chest.  This could be a new account the consumer sets up, or the player's wallet provided by the economy implementation, or 
 * another account that the player owns. 
 * 
 * When another player purchases an item from the store the consumer initiates a transfer from the purchaser's wallet, to the 
 * account that was setup for the chest shop, if successful they get the item.
 * 
 * To be able to offer dynamic account linkage does there need to be a way for a consumer to get a list of accounts that are valid 
 * for use in the player's current context (world, chunk, position. etc), or do we just provide API for grabbing all accounts owned
 * by the player.
 * 
 * Do we add inherent permissions on accounts? Ability to deposit but not withdraw? ability to check balance, 
 * but not withdraw/deposit, etc, or do we leave that up to the implementation and provide no API for checking these from Consumers.
 * 
 * Currencies: Multiple currency support is easily implemented by simply keeping track of balances per currency, but it also brings up
 * that some currencies will only support integer values.  Should we limit everything to integer operations for simplicity.
 * IE, everything happens in cents, and the Economies should format their numbers manually? or do we force handling currencies as
 * BigDecimals.
 * 
 */

public interface Economy {
    
    /**
     * Get's the player's wallet.  What they are currently holding.
     */
    public Account getWallet(Player player);
    
    // How else are would we do account lookups if we want to support something like banks?
    public Account getAccount(/* UUID? String? */  );

    public boolean transfer(Account from, Account to, Currency currency, Number amount);
    
    public boolean withdraw(Account from, Currency currency, Number amount);
    
    public boolean deposit(Account to, Currency currency, Number amount);
    
    public NumberFormat getFormatter(Currency currency);
    
    public String format(Currency currency, Number amount);
    
    public List<Currency> getCurrencies();
    
    public Double getExchangeRate(Currency from, Currency to);
}

public interface Account {
    
    public String getId();
    
    public boolean transfer(Account to, Currency currency, Number amount);
    
    public boolean withdraw(Currency currency, Number amount);
    
    public boolean deposit(Currency currency, Number amount);
    
    // Owners?
    public ? getOwner()
}

public interface Currency {
    public String getName();
    public String format(Number amount);
    public NumberFormat getFormatter();
}