using System.Drawing;
using System.Numerics;
using Dashboard.Drawing;
using Dashboard.Pal;
using Dashboard.Windowing;
using OpenTK.Graphics.OpenGL;
using OpenTK.Graphics.Wgl;
using OpenTK.Mathematics;
using ColorBuffer = OpenTK.Graphics.OpenGL.ColorBuffer;

namespace Dashboard.OpenGL.Drawing
{
    public class DeviceContextBase : IDeviceContextBase
    {
        private readonly Stack<Matrix4x4> _transforms = new Stack<Matrix4x4>();
        private readonly Stack<RectangleF> _clipRegions = new Stack<RectangleF>();
        private readonly Stack<RectangleF> _scissorRegions = new Stack<RectangleF>();

        public DeviceContext Context { get; private set; } = null!;
        IContextBase IContextExtensionBase.Context => Context;
        public string DriverName => "Dashboard OpenGL Device Context";
        public string DriverVendor => "Dashboard";
        public Version DriverVersion => new Version(0, 1);

        public RectangleF ClipRegion => _clipRegions.Peek();
        public RectangleF ScissorRegion => _scissorRegions.Peek();
        public Matrix4x4 Transforms => _transforms.Peek();
        public float Scale => ScaleOverride > 0 ? ScaleOverride : (Context.Window as IDpiAwareWindow)?.Scale ?? 1;
        public float ScaleOverride { get; set; } = -1f;


        public void Dispose()
        {
        }


        public void Require(DeviceContext context)
        {
            Context = context;

            ResetClip();
            ResetScissor();
            ResetTransforms();
        }


        void IContextExtensionBase.Require(IContextBase context) => Require((DeviceContext)context);

        public void ResetClip()
        {
            _clipRegions.Clear();

            SizeF size = ((GLDeviceContext)Context).GLContext.FramebufferSize;
            _clipRegions.Push(new RectangleF(0,0, size.Width, size.Height));

            SetClip(ClipRegion);
        }

        public void PushClip(RectangleF clipRegion)
        {
            clipRegion = new RectangleF(ClipRegion.X + clipRegion.X, ClipRegion.Y + clipRegion.Y,
                Math.Min(ClipRegion.Right - clipRegion.X, clipRegion.Width),
                Math.Min(ClipRegion.Bottom - clipRegion.Y, clipRegion.Height));
            _clipRegions.Push(clipRegion);

            SetClip(clipRegion);
        }

        public void PopClip()
        {
            _clipRegions.Pop();
            SetClip(ClipRegion);
        }

        public void ResetScissor()
        {
            GL.Disable(EnableCap.ScissorTest);
            _scissorRegions.Clear();
            SizeF size = ((GLDeviceContext)Context).GLContext.FramebufferSize;
            _scissorRegions.Push(new RectangleF(0,0, size.Width, size.Height));
        }

        public void PushScissor(RectangleF scissorRegion)
        {
            GL.Enable(EnableCap.ScissorTest);

            // scissorRegion = new RectangleF(scissorRegion.X + scissorRegion.X, scissorRegion.Y + scissorRegion.Y,
            //     Math.Min(ScissorRegion.Right - scissorRegion.X, scissorRegion.Width),
            //     Math.Min(ScissorRegion.Bottom - scissorRegion.Y, scissorRegion.Height));
            _scissorRegions.Push(scissorRegion);

            SetScissor(scissorRegion);
        }

        public void PopScissor()
        {
            if (_scissorRegions.Count == 1)
                GL.Disable(EnableCap.ScissorTest);

            _scissorRegions.Pop();
            SetScissor(ClipRegion);
        }

        private void SetClip(RectangleF rect)
        {
            SizeF size = ((GLDeviceContext)Context).GLContext.FramebufferSize;
            GL.Viewport(
                (int)Math.Round(rect.X),
                (int)Math.Round(size.Height - rect.Y - rect.Height),
                (int)Math.Round(rect.Width),
                (int)Math.Round(rect.Height));
        }

        void SetScissor(RectangleF rect)
        {
            SizeF size = ((GLDeviceContext)Context).GLContext.FramebufferSize;
            GL.Scissor(
                (int)Math.Round(rect.X),
                (int)Math.Round(size.Height - rect.Y - rect.Height),
                (int)Math.Round(rect.Width),
                (int)Math.Round(rect.Height));
        }

        public void ResetTransforms()
        {
            SizeF size = ((GLDeviceContext)Context).GLContext.FramebufferSize;
            Matrix4x4 m  = Matrix4x4.CreateOrthographicOffCenterLeftHanded(0, size.Width, size.Height, 0, 1, -1);

            _transforms.Clear();
            _transforms.Push(m);
        }

        public void PushTransforms(in Matrix4x4 matrix)
        {
            Matrix4x4 result = matrix * Transforms;
            _transforms.Push(result);
        }

        public void PopTransforms()
        {
            _transforms.Pop();
        }

        public void ClearColor(Color color)
        {
            GL.ClearColor(color.R / 255f, color.G / 255f, color.B / 255f, color.A / 255f);
            GL.Clear(ClearBufferMask.ColorBufferBit);
        }

        public void ClearDepth()
        {
            GL.Clear(ClearBufferMask.DepthBufferBit);
        }
    }
}