import java.awt.*;
import java.util.Arrays;

import javax.swing.JTextArea;

class Calculate extends Thread
{
	public static final int RUNNING = 0;

	public static final int PAUSED = 1;

	public static final int STOPPED = 2;

	private int status = STOPPED;

	private JTextArea textArea;

	private static final int MAX_PRIMES = 10000;

	int primesSaved = 0;

	long[] referencePrimes = new long[MAX_PRIMES]; // primes to check against

	long[] squaredPrimes = new long[MAX_PRIMES];// reference primes squared

	public Calculate(JTextArea ta)
	{
		textArea = ta;
	}

	public void pause()
	{
		status = PAUSED;
	}

	public void stopRunning()
	{
		status = STOPPED;
	}

	public void continueRunning()
	{
		status = RUNNING;
	}

	public int getStatus()
	{
		return status;
	}

	private void init()
	{
		status = RUNNING;
		Arrays.fill(referencePrimes, 0l);
		Arrays.fill(squaredPrimes, 0l);
		referencePrimes[0] = 3; // store initial prime
		squaredPrimes[0] = 9;
		textArea.append("2\n"); // don't have to verify
		textArea.append("3\n");
	}

	public void run()
	{
		init();
		long testValue = 5; // first number to test
		while (testValue < squaredPrimes[primesSaved] && status == RUNNING)
		{
			if (isPrime(testValue))
			{
				textArea.append(testValue + "\n");
				textArea.setCaretPosition(textArea.getText().length()-1);
				if (primesSaved < MAX_PRIMES - 1)
				{
					referencePrimes[++primesSaved] = testValue; // save prime
					squaredPrimes[primesSaved] = testValue * testValue;
				}
			}
			testValue += 2;
			Thread.yield();//be nice
			while (status == PAUSED)
			{
				try
				{
					sleep(200);
				} catch (InterruptedException ie)
				{
				}
			}
			if ((testValue - 1) % 200000l == 0)
				textArea.setText("");
		}
		textArea.append("Stopped.\n\n");
		status = STOPPED;
	}

	private boolean isPrime(long x)
	{
		int index = 0;
		while (index <= primesSaved && x >= squaredPrimes[index])
		{
			if (x % referencePrimes[index] == 0)
				return false;
			else
				index++;
		}
		return true;
	}
}