import org.junit.Assert;
import org.junit.Test;

import java.util.Arrays;
import java.util.Random;

public class TheClockwiseSpiralTest {

    TheClockwiseSpiral spiral = new TheClockwiseSpiral();

    private static int[][] check7894(int N) {
        int[][] a = new int[N][N];
        int oldN = N;
        int[] steps = {0, 1, 0, -1};
        int turn = 0;

        int c = 1;
        int i = 0;
        int j = 0;
        int passed = 0;

        while (N > 0) {
            a[i][j] = c;

            if ((c - passed) % N == 0) {
                passed += N;
                if (turn % 2 == 0)
                    N--;
                turn++;
            }

            i += steps[(turn + 4) % 4];
            j += steps[(turn + 5) % 4];
            c++;
        }
        N = oldN;
        for(i = 0; i < N/2; i+=2) {
            int[] tmp = Arrays.copyOf(a[i], N);
            a[i] = a[N -i];
            a[N - i] = tmp;
        }
        return a;
    }


    @Test
    public void randomized_30_tests() {
        Random random = new Random();
        for (int i = 0; i < 30; i++) {
            int n = random.nextInt(50);
            int[][] expected = check7894(n);
            Assert.assertArrayEquals(expected, spiral.createSpiral(n));
        }
    }
}