import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

public class PortImplementacja implements Port {

    private static ReentrantLock lock = new ReentrantLock();
    private static Condition cond = lock.newCondition();

    private static int merchants = 0;
    private static Integer pirateId = null;
    private static Set<Integer> merchantsId = new HashSet<Integer>();

    @Override
    public void kupiecIn(int id) {
        lock.lock();
        try {
            merchants++;
            while (merchants < 4 && pirateId != null) {
                cond.await();
            }
            merchantsId.add(id);
            merchants--;
            cond.signal();
        } catch (InterruptedException ignored) {
        } finally {
            lock.unlock();
        }
    }

    @Override
    public void kupiecOut(int id) {
        lock.lock();
        try {
            while (!merchantsId.contains(id)) {
                cond.await();
            }
            merchantsId.remove(id);
            cond.signal();
        } catch (InterruptedException ignored) {
        } finally {
            lock.unlock();
        }
    }

    @Override
    public void piratIn(int id) {
        lock.lock();
        try {
            while (!(merchantsId.isEmpty() && pirateId == null)) {
                cond.await();
            }
            pirateId = id;

            cond.signal();
        } catch (InterruptedException ignored) {
        } finally {
            lock.unlock();
        }
    }

    @Override
    public void piratOut(int id) {
        lock.lock();
        try {
            while (pirateId != id) {
                cond.await();
            }
            pirateId = null;

            cond.signal();
        } catch (InterruptedException ignored) {
        } finally {
            lock.unlock();
        }
    }
}