import java.util.Random;

import org.junit.*;

public class TinyCipherTests {
	
	private static final String SECRET = "secret";
	
	@Test
	public void testSimpleRoundtrip() {
		exhaustivelyCheckRoundtrip(8);
	}
	
	/**
	* Thanks are due to Dmitry Kichinsky for pointing out this bug.
	*/
	@Test
	public void testOddBlockSizeRoundtrip() {
		exhaustivelyCheckRoundtrip(9);
	}
	
	private void exhaustivelyCheckRoundtrip(int bits) {
		TinyCipher c = newTinyCipher(bits);
		for (int plaintext = 0; plaintext < (1 << bits); ++plaintext) {
			checkRoundtrip(c, plaintext);
		}
	}
	
	@Test
	public void testFullWidthBlockSizeRoundtrip() {
		sparselyCheckRoundtrip(32);
	}
	
	private void sparselyCheckRoundtrip(int bits) {
		TinyCipher c = newTinyCipher(bits);
		Random rnd = new Random(SECRET.hashCode());
		int mask = (int)((1L << bits) - 1);
		for (int i = 0; i < 100000; ++i) {
			int plaintext = rnd.nextInt() & mask;
			checkRoundtrip(c, plaintext);
		}
	}
	
	private TinyCipher newTinyCipher(int bits) {
		return new TinyCipher(bits, SECRET.getBytes());
	}
	
	private void checkRoundtrip(TinyCipher c, int plaintext) {
		int ciphertext = c.encrypt(plaintext);
		int recoveredPlaintext = c.decrypt(ciphertext);
		Assert.assertEquals(plaintext, recoveredPlaintext);
	}
	
}