using AcDream.App.Rendering;
using Silk.NET.OpenGL;

namespace AcDream.App.Tests.Rendering;

public sealed class RenderFrameGlStateControllerTests
{
    [Fact]
    public void RestoreFrameDefaults_ReestablishesTheCompleteFrameGlobalContract()
    {
        var api = new RecordingApi();
        var state = new RenderFrameGlStateController(api);

        state.RestoreFrameDefaults();

        Assert.Equal(
            [
                "cap:ScissorTest:False",
                "cap:StencilTest:False",
                "cap:Blend:False",
                "cap:SampleAlphaToMaskSgis:False",
                "cap:ClipDistance0:False",
                "cap:ClipDistance1:False",
                "cap:ClipDistance2:False",
                "cap:ClipDistance3:False",
                "cap:ClipDistance4:False",
                "cap:ClipDistance5:False",
                "cap:ClipDistance6:False",
                "cap:ClipDistance7:False",
                "color-mask:True:True:True:True",
                "stencil-mask:255",
                "depth-mask:True",
                "depth-func:Less",
                "cap:DepthTest:True",
                "cap:CullFace:False",
                "cull:Back",
                "front:CW",
                "program:0",
                "vao:0",
                "buffer:ArrayBuffer:0",
            ],
            api.Calls);
    }

    [Fact]
    public void PortalDepthMask_SuccessExitRestoresTheSameCullOffConvention()
    {
        string source = File.ReadAllText(Path.Combine(
            FindRepoRoot(),
            "src",
            "AcDream.App",
            "Rendering",
            "PortalDepthMaskRenderer.cs"));
        int restore = source.IndexOf(
            "// ---- restore the frame-global convention ----",
            StringComparison.Ordinal);

        Assert.True(restore >= 0, "Missing portal-depth state restore block.");
        string restoreBlock = source[restore..];
        Assert.Contains("_gl.Disable(EnableCap.CullFace);", restoreBlock);
        Assert.DoesNotContain("_gl.Enable(EnableCap.CullFace);", restoreBlock);
    }

    private static string FindRepoRoot()
    {
        DirectoryInfo? directory = new(AppContext.BaseDirectory);
        while (directory is not null)
        {
            if (File.Exists(Path.Combine(directory.FullName, "AcDream.slnx")))
                return directory.FullName;
            directory = directory.Parent;
        }

        throw new DirectoryNotFoundException("Could not find AcDream.slnx.");
    }

    private sealed class RecordingApi : IRenderFrameGlStateApi
    {
        public List<string> Calls { get; } = [];

        public void SetCapability(EnableCap capability, bool enabled) =>
            Calls.Add($"cap:{capability}:{enabled}");

        public void ColorMask(bool red, bool green, bool blue, bool alpha) =>
            Calls.Add($"color-mask:{red}:{green}:{blue}:{alpha}");

        public void StencilMask(uint mask) => Calls.Add($"stencil-mask:{mask}");

        public void DepthMask(bool enabled) => Calls.Add($"depth-mask:{enabled}");

        public void DepthFunc(DepthFunction function) =>
            Calls.Add($"depth-func:{function}");

        public void CullFace(TriangleFace face) => Calls.Add($"cull:{face}");

        public void FrontFace(FrontFaceDirection direction) =>
            Calls.Add($"front:{direction}");

        public void UseProgram(uint program) => Calls.Add($"program:{program}");

        public void BindVertexArray(uint vertexArray) => Calls.Add($"vao:{vertexArray}");

        public void BindBuffer(BufferTargetARB target, uint buffer) =>
            Calls.Add($"buffer:{target}:{buffer}");
    }
}