using System.Linq;
using StellaOps.Zastava.Observer.Runtime;
using StellaOps.Zastava.Observer.Tests.TestSupport;
using Xunit;

namespace StellaOps.Zastava.Observer.Tests.Runtime;

public sealed class ElfBuildIdReaderTests
{
    [Fact]
    public async Task TryReadBuildIdAsync_ReturnsExpectedHex()
    {
        using var temp = new TempDirectory();
        var elfPath = Path.Combine(temp.RootPath, "bin", "example");
        var buildIdBytes = Enumerable.Range(0, 20).Select(static index => (byte)(index + 1)).ToArray();
        ElfTestFileBuilder.CreateElfWithBuildId(elfPath, buildIdBytes);

        var buildId = await ElfBuildIdReader.TryReadBuildIdAsync(elfPath, CancellationToken.None);

        Assert.Equal(Convert.ToHexString(buildIdBytes).ToLowerInvariant(), buildId);
    }

    [Fact]
    public async Task TryReadBuildIdAsync_InvalidFileReturnsNull()
    {
        using var temp = new TempDirectory();
        var path = Path.Combine(temp.RootPath, "bin", "invalid");
        Directory.CreateDirectory(Path.GetDirectoryName(path)!);
        await File.WriteAllTextAsync(path, "not-an-elf");

        var buildId = await ElfBuildIdReader.TryReadBuildIdAsync(path, CancellationToken.None);

        Assert.Null(buildId);
    }

    private sealed class TempDirectory : IDisposable
    {
        public TempDirectory()
        {
            RootPath = Path.Combine(Path.GetTempPath(), "elf-buildid-tests", Guid.NewGuid().ToString("N"));
            Directory.CreateDirectory(RootPath);
        }

        public string RootPath { get; }

        public void Dispose()
        {
            try
            {
                if (Directory.Exists(RootPath))
                {
                    Directory.Delete(RootPath, recursive: true);
                }
            }
            catch
            {
            }
        }
    }
}