using System.Security.Cryptography;
using System.Text;
using FluentAssertions;
using StellaOps.AirGap.Importer.Reconciliation;

namespace StellaOps.AirGap.Importer.Tests.Reconciliation;

public sealed class EvidenceDirectoryDiscoveryTests
{
    [Fact]
    public void Discover_ReturnsDeterministicRelativePathsAndHashes()
    {
        var root = Path.Combine(Path.GetTempPath(), "stellaops-evidence-" + Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(root);

        try
        {
            WriteUtf8(Path.Combine(root, "sboms", "a.cdx.json"), "{\"bom\":1}");
            WriteUtf8(Path.Combine(root, "attestations", "z.intoto.jsonl.dsig"), "dsse");
            WriteUtf8(Path.Combine(root, "vex", "v.openvex.json"), "{\"vex\":true}");

            var discovered = EvidenceDirectoryDiscovery.Discover(root);
            discovered.Should().HaveCount(3);

            discovered.Select(d => d.RelativePath).Should().Equal(
                "attestations/z.intoto.jsonl.dsig",
                "sboms/a.cdx.json",
                "vex/v.openvex.json");

            discovered[0].Kind.Should().Be(EvidenceFileKind.Attestation);
            discovered[1].Kind.Should().Be(EvidenceFileKind.Sbom);
            discovered[2].Kind.Should().Be(EvidenceFileKind.Vex);

            discovered[0].ContentSha256.Should().Be(HashUtf8("dsse"));
            discovered[1].ContentSha256.Should().Be(HashUtf8("{\"bom\":1}"));
            discovered[2].ContentSha256.Should().Be(HashUtf8("{\"vex\":true}"));
        }
        finally
        {
            Directory.Delete(root, recursive: true);
        }
    }

    [Fact]
    public void Discover_WhenDirectoryMissing_Throws()
    {
        var missing = Path.Combine(Path.GetTempPath(), "stellaops-missing-" + Guid.NewGuid().ToString("N"));
        Action act = () => EvidenceDirectoryDiscovery.Discover(missing);
        act.Should().Throw<DirectoryNotFoundException>();
    }

    private static void WriteUtf8(string path, string content)
    {
        Directory.CreateDirectory(Path.GetDirectoryName(path)!);
        File.WriteAllText(path, content, new UTF8Encoding(encoderShouldEmitUTF8Identifier: false));
    }

    private static string HashUtf8(string content)
    {
        using var sha256 = SHA256.Create();
        var bytes = Encoding.UTF8.GetBytes(content);
        var hash = sha256.ComputeHash(bytes);
        return "sha256:" + Convert.ToHexString(hash).ToLowerInvariant();
    }
}