package adapter;

/**
 * The Target interface — what YOUR application's code expects.
 * Every payment gateway in your system must implement this.
 * Written to handle modern async-style payment flows.
 */
public interface PaymentGateway {
    boolean charge(String customerId, double amount, String currency);
    boolean refund(String transactionId, double amount);
    String getStatus(String transactionId);
}