import java.nio.file.Path;
import java.time.Duration;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.locks.LockSupport;

public class VirtualThreadsOnly {
    private static final AtomicLong computations = new AtomicLong(0);

    public static void main(String[] args) throws Exception {
        Duration duration = Duration.ofSeconds(10);
        int num_virt_threads = 10_000_000;

        if (args.length == 2) {
            try {
                duration = Duration.ofSeconds(Integer.parseInt(args[0]));
                num_virt_threads = Integer.parseInt(args[1]);
            } catch (NumberFormatException e) {
                System.err.println("Invalid duration argument: " + args[0]);
                System.exit(1);
            }
        }

        System.out.println(
                "Starting VirtualThreadsOnly for " + duration + " ms with " + num_virt_threads + " virtual threads");

        try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) {
            for (int i = 0; i < num_virt_threads; i++) {
                executor.submit(() -> {
                    double result = 0;
                    for (int j = 0; j < 5000; j++) {
                        result += Math.sin(j) * Math.cos(j);
                    }
                    computations.addAndGet((long) result);

                    LockSupport.parkNanos(100_00);
                });
            }
            executor.shutdown();
            if (!executor.awaitTermination(duration.toMillis() + 5000, TimeUnit.MILLISECONDS)) {
                System.err.println("Virtual threads did not complete in time.");
                System.exit(1);
            }
        }

        System.out.println("Test finished successfully.");
    }
}