namespace HSchool.AppHost.Tests;

public class LaunchBuildStampTests
{
    private static readonly DateTime Inputs = new(2026, 1, 1, 12, 0, 0, DateTimeKind.Utc);
    private static readonly DateTime Outputs = new(2026, 1, 1, 12, 5, 0, DateTimeKind.Utc);
    private static readonly DateTime Newer = new(2026, 1, 1, 12, 10, 0, DateTimeKind.Utc);

    [Fact]
    public void MissingDll_NeedsBuild()
    {
        using var repo = FreshRepo();
        File.Delete(repo.Dll("HSchool.Server"));

        Assert.True(LaunchBuildStamp.NeedsBuild(repo.Root));
    }

    [Fact]
    public void FreshDlls_SkipBuild()
    {
        using var repo = FreshRepo();

        Assert.False(LaunchBuildStamp.NeedsBuild(repo.Root));
    }

    [Fact]
    public void NewerCs_NeedsBuild()
    {
        using var repo = FreshRepo();
        repo.Touch("src/HSchool.Server/Program.cs", Newer);

        Assert.True(LaunchBuildStamp.NeedsBuild(repo.Root));
    }

    [Fact]
    public void NewerTsOrJsonc_SkipBuild()
    {
        using var repo = FreshRepo();
        repo.Write("src/HSchool.Client/src/main.ts", "export {}");
        repo.Write("src/HSchool.Server/mods/core/defs/foo.jsonc", "{}");
        repo.Touch("src/HSchool.Client/src/main.ts", Newer);
        repo.Touch("src/HSchool.Server/mods/core/defs/foo.jsonc", Newer);

        Assert.False(LaunchBuildStamp.NeedsBuild(repo.Root));
    }

    [Fact]
    public void FilesInBinObjNodeModules_AreNotInputs()
    {
        using var repo = FreshRepo();
        repo.Write("src/HSchool.Server/bin/Debug/net10.0/Generated.cs", "class G {}");
        repo.Write("src/HSchool.Server/obj/Debug/net10.0/Generated.cs", "class G {}");
        repo.Write("src/HSchool.Client/node_modules/pkg/index.cs", "class N {}");
        repo.Touch("src/HSchool.Server/bin/Debug/net10.0/Generated.cs", Newer);
        repo.Touch("src/HSchool.Server/obj/Debug/net10.0/Generated.cs", Newer);
        repo.Touch("src/HSchool.Client/node_modules/pkg/index.cs", Newer);

        Assert.False(LaunchBuildStamp.NeedsBuild(repo.Root));
    }

    [Fact]
    public void NewerDirectoryPackagesProps_NeedsBuild()
    {
        using var repo = FreshRepo();
        repo.Touch("Directory.Packages.props", Newer);

        Assert.True(LaunchBuildStamp.NeedsBuild(repo.Root));
    }

    [Fact]
    public void ReleaseLooksAtReleaseBin()
    {
        using var repo = FreshRepo();

        Assert.False(LaunchBuildStamp.NeedsBuild(repo.Root, "Debug"));
        Assert.True(LaunchBuildStamp.NeedsBuild(repo.Root, "Release"));

        repo.WriteDll("HSchool.AppHost", "Release");
        repo.WriteDll("HSchool.Server", "Release");
        repo.TouchDlls("Release", Outputs);

        Assert.False(LaunchBuildStamp.NeedsBuild(repo.Root, "Release"));
    }

    private static TempRepo FreshRepo()
    {
        var repo = new TempRepo();
        repo.Write("global.json", "{}");
        repo.Write("Directory.Build.props", "<Project />");
        repo.Write("Directory.Packages.props", "<Project />");
        repo.Write("src/HSchool.AppHost/AppHost.cs", "class A {}");
        repo.Write("src/HSchool.AppHost/HSchool.AppHost.csproj", "<Project />");
        repo.Write("src/HSchool.Server/Program.cs", "class S {}");
        repo.Write("src/HSchool.Server/HSchool.Server.csproj", "<Project />");
        repo.WriteDll("HSchool.AppHost");
        repo.WriteDll("HSchool.Server");
        repo.Touch("global.json", Inputs);
        repo.Touch("Directory.Build.props", Inputs);
        repo.Touch("Directory.Packages.props", Inputs);
        repo.Touch("src/HSchool.AppHost/AppHost.cs", Inputs);
        repo.Touch("src/HSchool.AppHost/HSchool.AppHost.csproj", Inputs);
        repo.Touch("src/HSchool.Server/Program.cs", Inputs);
        repo.Touch("src/HSchool.Server/HSchool.Server.csproj", Inputs);
        repo.TouchDlls("Debug", Outputs);
        return repo;
    }

    private sealed class TempRepo : IDisposable
    {
        public string Root { get; } = Path.Combine(Path.GetTempPath(), "h-school-stamp-" + Guid.NewGuid().ToString("N"));

        public TempRepo() => Directory.CreateDirectory(Root);

        public string Write(string relative, string contents)
        {
            var path = PathUnder(relative);
            var dir = Path.GetDirectoryName(path);
            if (dir is not null)
            {
                Directory.CreateDirectory(dir);
            }

            File.WriteAllText(path, contents);
            return path;
        }

        public string WriteDll(string project, string configuration = "Debug") =>
            Write($"src/{project}/bin/{configuration}/{LaunchBuildStamp.TargetFramework}/{project}.dll", "dll");

        public string Dll(string project, string configuration = "Debug") =>
            PathUnder($"src/{project}/bin/{configuration}/{LaunchBuildStamp.TargetFramework}/{project}.dll");

        public void Touch(string relative, DateTime utc) => File.SetLastWriteTimeUtc(PathUnder(relative), utc);

        public void TouchDlls(string configuration, DateTime utc)
        {
            foreach (var project in LaunchBuildStamp.OutputProjects)
            {
                Touch($"src/{project}/bin/{configuration}/{LaunchBuildStamp.TargetFramework}/{project}.dll", utc);
            }
        }

        public void Dispose()
        {
            try
            {
                Directory.Delete(Root, recursive: true);
            }
            catch (IOException)
            {
            }
        }

        private string PathUnder(string relative) =>
            Path.Combine(Root, relative.Replace('/', Path.DirectorySeparatorChar));
    }
}