using AdventOfCode.Extensions;
namespace AdventOfCode.Extensions.Tests;

public class EnumerableExtensionsTest
{
    [Fact]
    public void Combinations_12_2_equals_12()
    {
        int[] data = [1, 2];

        var actual = data.Combinations(2).ToArray();

        Assert.Contains([1, 2], actual);
        Assert.Equal(1, actual.Length);
    }
    
    [Fact]
    public void Combinations_123_2_equals_12_13_23()
    {
        int[] data = [1, 2, 3];

        var actual = data.Combinations(2).ToArray();

        Assert.Contains([1, 2], actual);
        Assert.Contains([1, 3], actual);
        Assert.Contains([2, 3], actual);
        Assert.Equal(3, actual.Length);
    }
    
    [Fact]
    public void Combinations_123_3_equals_123()
    {
        int[] data = [1, 2, 3];

        var actual = data.Combinations(3).ToArray();

        Assert.Contains([1, 2, 3], actual);
        Assert.Equal(1, actual.Length);
    }
    
    [Fact]
    public void Permutations_12_2_equals_11_12_21_22()
    {
        int[] data = [1, 2];

        var actual = data.Permutations(2).ToArray();

        Assert.Contains([1, 1], actual);
        Assert.Contains([1, 2], actual);
        Assert.Contains([2, 1], actual);
        Assert.Contains([2, 2], actual);
        Assert.Equal(4, actual.Length);
    }
    
    [Fact]
    public void Permutations_123_2_equals_11_12_13_21_22_23_31_32_33()
    {
        int[] data = [1, 2, 3];

        var actual = data.Permutations(2).ToArray();

        Assert.Contains([1, 1], actual);
        Assert.Contains([1, 2], actual);
        Assert.Contains([2, 1], actual);
        Assert.Contains([2, 2], actual);
        Assert.Contains([3, 1], actual);
        Assert.Contains([3, 2], actual);
        Assert.Contains([3, 3], actual);
        Assert.Equal(9, actual.Length);
    }
}