using StgSharp.Graphics;

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.Text;
using System.Threading.Tasks;

namespace StgSharp.Graphics.GL.ShaderEdit
{
    public class ShaderGenerator
    {
        private List<string> codeList;
        private List<ShaderFunction> usedShaderFunctions;

        public Uniform<T> DefineUniform<T>() where T : struct
        {
            throw new NotImplementedException();
        }
    }

    public class ShaderFunction
    {
        private string name;
        private List<string> codeList;
        private List<ShaderParameter> inputList;
        private ShaderParameter outPut;

        public int ParameterCount
        {
            get { return inputList.Count; }
        }

        public void EmitCall(ShaderFunction function, ShaderParameter outPut, params ShaderParameter[] inputParams)
        {
            if (inputParams.Length != function.ParameterCount)
            {
                throw new ArgumentException("Provided parameters does not match function's parameter list.");
            }
            if (!ShaderParameter.IsSameType(outPut, function.outPut))
            {
                throw new Exception("Provided parameters does not match function's parameter list.");
            }
            for (int i = 0; i < inputParams.Length; i++)
            {
                if (!ShaderParameter.IsSameType(function.inputList[i], inputParams[i]))
                {
                    throw new Exception("Provided parameters does not match function's parameter list.");
                }
            }
            string codeLine = "";
            if (outPut != ShaderParameter.Void)
            {
                codeLine += $"{outPut.name} = ";
            }
            codeLine += $"{function.name}(";
            foreach (ShaderParameter inputParam in inputParams)
            {
                codeLine += inputParam.name;
            }
            codeLine += ");\n";
            codeList.Add(codeLine);
        }
    }

    public class ShaderParameter
    {
        internal readonly InternalShaderType type;
        internal readonly string name;
        internal readonly bool isReadOnly;

        public ShaderParameter(string name, InternalShaderType type)
        {
            this.name = name;
            this.type = type;
            isReadOnly = false;
        }

        public static readonly ShaderParameter Void = new ShaderParameter("", InternalShaderType.Void);

        public static bool IsSameType(ShaderParameter param1, ShaderParameter param2)
        {
            if (param1.type != InternalShaderType.Struct)
            {
                return param1.type == param2.type;
            }
            else
            {
                throw new Exception("Struct is currently not supported.");
            }
        }
    }

    public enum InternalShaderType
    {
#pragma warning disable CS1591
        Struct, Void,
        Int, UInt,
        Float, Double,
        Vector2, Vector3, Vector4,
        VectorD2, VectorD3, VectorD4,
        Matrix2x2, Matrix2x3, Matrix2x4,
        Matrix3x2, Matrix3x3, Matrix3x4,
        Matrix4x2, Matrix4x3, Matrix4x4,
#pragma warning restore CS1591
    }
}