import java.util.ArrayList;

public class TransferManager {
    private ArrayList<Transfer> openTransfers;
    private int issuedTransfers;
    private int performedTransfers;

    public TransferManager() {
        openTransfers = new ArrayList<Transfer>();
        issuedTransfers = 0;
        performedTransfers = 0;
    }

    public void issueTransfer(Account from, Account to, int amount) {
        openTransfers.add(new Transfer(from, to, amount));
        issuedTransfers++;
    }

    public void performTransfers() {
        for(Transfer transaction : openTransfers) {
            transaction.performTransfer();
            performedTransfers++;
        }
        openTransfers.clear();
    }

    @Override
    public String toString() {
        return "TransferManager (openTransfers: " + openTransfers.size() + "; issuedTransfers: " + issuedTransfers + "; performedTransfers: " + performedTransfers + ")";
    }

    private static class Transfer {
        private Account from, to;
        private int amount;

        public Transfer(Account from, Account to, int amount) {
            this.from = from;
            this.to = to;
            this.amount = amount;
        }

        public void performTransfer() {
            from.transfer(-amount);
            to.transfer(amount);
        }
    }
}