using System.Security.Cryptography;
using System.Text;
using StellaOps.Cryptography;
using StellaOps.Cryptography.Digests;
using StellaOps.TestKit;
using Xunit;
namespace StellaOps.Cryptography.Tests;

public sealed class Sha256DigestTests
{
    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public void Normalize_AllowsBareHex_WhenPrefixNotRequired()
    {
        var hex = new string('a', Sha256Digest.HexLength);
        Assert.Equal($"sha256:{hex}", Sha256Digest.Normalize(hex));
    }

    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public void Normalize_NormalizesPrefixAndHexToLower()
    {
        var hexUpper = new string('A', Sha256Digest.HexLength);
        Assert.Equal(
            $"sha256:{new string('a', Sha256Digest.HexLength)}",
            Sha256Digest.Normalize($"SHA256:{hexUpper}"));
    }

    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public void Normalize_RequiresPrefix_WhenConfigured()
    {
        var hex = new string('a', Sha256Digest.HexLength);
        var ex = Assert.Throws<FormatException>(() => Sha256Digest.Normalize(hex, requirePrefix: true, parameterName: "sbomDigest"));
        Assert.Contains("sbomDigest", ex.Message, StringComparison.Ordinal);
        Assert.Contains("sha256:", ex.Message, StringComparison.Ordinal);
    }

    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public void ExtractHex_ReturnsLowercaseHex()
    {
        var hexUpper = new string('A', Sha256Digest.HexLength);
        Assert.Equal(new string('a', Sha256Digest.HexLength), Sha256Digest.ExtractHex($"sha256:{hexUpper}"));
    }

    [Trait("Category", TestCategories.Unit)]
    [Fact]
    public void Compute_UsesCryptoHashStack()
    {
        var hash = CryptoHashFactory.CreateDefault();
        var content = Encoding.UTF8.GetBytes("hello");

        var expectedHex = Convert.ToHexStringLower(SHA256.HashData(content));
        Assert.Equal($"sha256:{expectedHex}", Sha256Digest.Compute(hash, content));
    }
}