using System;
using System.Collections;
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; }
        public DrawCommand<LineCommandArgs> DrawLine { get; }
        public RectCommand DrawRectF { get; }
        public RectCommand DrawRectS { get; }
        public RectCommand DrawRectFS { get; }

        private DbBaseCommands() : base("DB_base",
            new[]
            {
                BrushExtension.Instance,
            })
        {
            AddCommand(DrawPoint = new DrawCommand<PointCommandArgs>("Point", this, PointCommandArgs.CommandSize));
            AddCommand(DrawLine = new DrawCommand<LineCommandArgs>("Line", this, LineCommandArgs.CommandSize));
            AddCommand(DrawRectF = new RectCommand(RectCommand.Mode.Fill));
            AddCommand(DrawRectS = new RectCommand(RectCommand.Mode.Strike));
            AddCommand(DrawRectFS = new RectCommand(RectCommand.Mode.FillStrike));
        }

        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>();
    }

    public struct LineCommandArgs : IParameterSerializer<LineCommandArgs>
    {
        public Vector3 Start { get; private set; }
        public Vector3 End { get; private set; }
        public float Size { get; private set; }
        public IBrush? Brush { get; private set; }

        public LineCommandArgs(Vector3 start, Vector3 end, float size, IBrush brush)
        {
            Start = start;
            End = end;
            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(Start, End, Size, queue.RequireResource(Brush!))
            };

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

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

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

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

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

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

    public enum StrikeKind
    {
        Inset = -1,
        Center = 0,
        Outset = 1,
    }

    public class RectCommand : IDrawCommand<RectCommandArgs>
    {
        private readonly Mode _mode;
        public string Name { get; }
        public IDrawExtension Extension { get; }
        public int Length { get; }

        public RectCommand(Mode mode)
        {
            Extension = DbBaseCommands.Instance;
            _mode = mode;

            switch (mode)
            {
            case Mode.Fill:
                Name = "RectF";
                Length = Unsafe.SizeOf<RectF>();
                break;
            case Mode.Strike:
                Name = "RectS";
                Length = Unsafe.SizeOf<RectS>();
                break;
            default:
                Name = "RectFS";
                Length = Unsafe.SizeOf<RectFS>();
                break;
            }
        }

        object? IDrawCommand.GetParams(DrawQueue queue, ReadOnlySpan<byte> param)
        {
            return GetParams(queue, param);
        }

        public RectCommandArgs GetParams(DrawQueue queue, ReadOnlySpan<byte> param)
        {
            if (param.Length < Length)
                throw new Exception("Not enough bytes");

            RectCommandArgs args;

            switch (_mode)
            {
            case Mode.Fill:
                ref readonly RectF f = ref MemoryMarshal.AsRef<RectF>(param);
                args = new RectCommandArgs(f.Start, f.End, (IBrush)queue.Resources[f.FillBrushIndex]);
                break;
            case Mode.Strike:
                ref readonly RectS s = ref MemoryMarshal.AsRef<RectS>(param);
                args = new RectCommandArgs(s.Start, s.End, (IBrush)queue.Resources[s.StrikeBrushIndex], s.StrikeSize, s.StrikeKind);
                break;
            default:
                ref readonly RectFS fs = ref MemoryMarshal.AsRef<RectFS>(param);
                args = new RectCommandArgs(fs.Start, fs.End, (IBrush)queue.Resources[fs.FillBrushIndex],
                    (IBrush)queue.Resources[fs.StrikeBrushIndex], fs.StrikeSize, fs.StrikeKind);
                break;
            }

            return args;
        }

        public int WriteParams(DrawQueue queue, object? obj, Span<byte> param)
        {
            return WriteParams(queue, (RectCommandArgs)obj, param);
        }

        public int WriteParams(DrawQueue queue, RectCommandArgs obj, Span<byte> param)
        {
            if (param.Length < Length)
                return Length;

            switch (_mode)
            {
                case Mode.Fill:
                    ref RectF f = ref MemoryMarshal.AsRef<RectF>(param);
                    f.Start = obj.Start;
                    f.End = obj.End;
                    f.FillBrushIndex = queue.RequireResource(obj.FillBrush!);
                    break;
                case Mode.Strike:
                    ref RectS s = ref MemoryMarshal.AsRef<RectS>(param);
                    s.Start = obj.Start;
                    s.End = obj.End;
                    s.StrikeBrushIndex = queue.RequireResource(obj.StrikeBrush!);
                    s.StrikeSize = obj.StrikeSize;
                    s.StrikeKind = obj.StrikeKind;
                    break;
                default:
                    ref RectFS fs = ref MemoryMarshal.AsRef<RectFS>(param);
                    fs.Start = obj.Start;
                    fs.End = obj.End;
                    fs.FillBrushIndex = queue.RequireResource(obj.FillBrush!);
                    fs.StrikeBrushIndex = queue.RequireResource(obj.StrikeBrush!);
                    fs.StrikeSize = obj.StrikeSize;
                    fs.StrikeKind = obj.StrikeKind;
                    break;
            }

            return Length;
        }

        [Flags]
        public enum Mode
        {
            Fill = 1,
            Strike = 2,
            FillStrike = Fill | Strike,
        }

        private record struct RectF(Vector3 Start, Vector3 End, int FillBrushIndex);
        private record struct RectS(Vector3 Start, Vector3 End, int StrikeBrushIndex, float StrikeSize, StrikeKind StrikeKind);
        private record struct RectFS(Vector3 Start, Vector3 End, int FillBrushIndex, int StrikeBrushIndex, float StrikeSize, StrikeKind StrikeKind);
    }

    public struct RectCommandArgs
    {
        public Vector3 Start { get; private set; }
        public Vector3 End { get; private set; }
        public StrikeKind StrikeKind { get; private set; } = StrikeKind.Center;
        public float StrikeSize { get; private set; } = 0f;
        public IBrush? FillBrush { get; private set; } = null;
        public IBrush? StrikeBrush { get; private set; } = null;
        public bool IsStruck => StrikeSize != 0;

        public RectCommandArgs(Vector3 start, Vector3 end, IBrush fillBrush)
        {
            Start = start;
            End = end;
            FillBrush = fillBrush;
        }

        public RectCommandArgs(Vector3 start, Vector3 end, IBrush strikeBrush, float strikeSize, StrikeKind strikeKind)
        {
            Start = start;
            End = end;
            StrikeBrush = strikeBrush;
            StrikeSize = strikeSize;
            StrikeKind = strikeKind;
        }

        public RectCommandArgs(Vector3 start, Vector3 end, IBrush fillBrush, IBrush strikeBrush, float strikeSize,
            StrikeKind strikeKind)
        {
            Start = start;
            End = end;
            FillBrush = fillBrush;
            StrikeBrush = strikeBrush;
            StrikeSize = strikeSize;
            StrikeKind = strikeKind;
        }
    }
}