using System;
using System.Diagnostics.CodeAnalysis;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace Dashboard.Drawing
{
    public class DbBaseCommands : DrawExtension
    {
        public DrawCommand<PointCommandArgs> DrawPoint { get; }

        private DbBaseCommands() : base("DB_base",
            new[]
            {
                BrushExtension.Instance,
            })
        {
            AddCommand(DrawPoint = new DrawCommand<PointCommandArgs>("Point", this, PointCommandArgs.CommandSize));
        }

        public static readonly DbBaseCommands Instance = new DbBaseCommands();
    }

    public struct PointCommandArgs : IParameterSerializer<PointCommandArgs>
    {
        public Vector3 Position { get; private set; }
        public float Size { get; private set; }
        public IBrush? Brush { get; private set; }

        public PointCommandArgs(Vector3 position, float size, IBrush brush)
        {
            Position = position;
            Brush = brush;
            Size = size;
        }
         
        public int Serialize(DrawQueue queue, Span<byte> bytes)
        {
            if (bytes.Length < CommandSize)
                return CommandSize;

            Span<Value> value = stackalloc Value[]
            {
                new Value(Position, Size, queue.RequireResource(Brush!))
            };

            MemoryMarshal.AsBytes(value).CopyTo(bytes);
            return CommandSize;
        }

        [MemberNotNull(nameof(Brush))]
        public void Deserialize(DrawQueue queue, ReadOnlySpan<byte> bytes)
        {
            if (bytes.Length < CommandSize)
                throw new Exception("Not enough bytes");

            Value value = MemoryMarshal.AsRef<Value>(bytes);

            Position = value.Position;
            Size = value.Size;
            Brush = (IBrush)queue.Resources[value.BrushIndex];
        }

        private record struct Value(Vector3 Position, float Size, int BrushIndex);

        public static readonly int CommandSize = Unsafe.SizeOf<Value>();
    }
}