package proxy;

import java.time.Instant;

/**
 * Logging Proxy — adds timing and audit logging around every query
 * without touching RealDatabaseConnection or any of its callers.
 *
 * This is the "cross-cutting concern" use case of Proxy,
 * the same mechanism behind Spring AOP's @Around advice.
 */
public class LoggingProxy implements DatabaseConnection {

    private final DatabaseConnection target;

    public LoggingProxy(DatabaseConnection target) {
        this.target = target;
    }

    @Override
    public void connect() {
        System.out.println("[Log] connect() at " + Instant.now());
        target.connect();
    }

    @Override
    public String executeQuery(String sql) {
        long start = System.currentTimeMillis();
        System.out.println("[Log] QUERY START: " + sql);
        String result = target.executeQuery(sql);
        long elapsed = System.currentTimeMillis() - start;
        System.out.println("[Log] QUERY END: " + elapsed + "ms | result: " + result);
        return result;
    }

    @Override
    public void disconnect() {
        System.out.println("[Log] disconnect() at " + Instant.now());
        target.disconnect();
    }
}