using OpenTK.Graphics.OpenGL4;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection.Metadata;
using System.Text;
using System.Threading.Tasks;

namespace Voxel
{
    public class Shader
    {
        int handle;
        private bool disposedValue = false;

        public Shader(string vertexPath, string fragmentPath)
        {
            string vertexShaderSource = File.ReadAllText(vertexPath);
            string fragmentShaderSource = File.ReadAllText(fragmentPath);

            int vertexShader = GL.CreateShader(ShaderType.VertexShader);
            int fragmentShader = GL.CreateShader(ShaderType.FragmentShader);

            GL.ShaderSource(vertexShader, vertexShaderSource);
            GL.ShaderSource(fragmentShader, fragmentShaderSource);

            GL.CompileShader(vertexShader);
            GL.GetShader(vertexShader, ShaderParameter.CompileStatus, out int success);
            if (success == 0)
            {
                string infoLog = GL.GetShaderInfoLog(vertexShader);
                Console.WriteLine(infoLog);
            }

            GL.CompileShader(fragmentShader);
            if (success == 0)
            {
                string infoLog = GL.GetShaderInfoLog(fragmentShader);
                Console.WriteLine(infoLog);
            }

            // attach

            handle = GL.CreateProgram();

            GL.AttachShader(handle, vertexShader);
            GL.AttachShader(handle, fragmentShader);

            GL.LinkProgram(handle);

            GL.GetProgram(handle, GetProgramParameterName.LinkStatus, out success);
            if (success == 0)
            {
                string infoLog = GL.GetProgramInfoLog(handle);
                Console.WriteLine(infoLog);
            }

            GL.DetachShader(handle, vertexShader);
            GL.DetachShader(handle, fragmentShader);
            GL.DeleteShader(fragmentShader);
            GL.DeleteShader(vertexShader);
        }

        public void Use()
        {
            GL.UseProgram(handle);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (!disposedValue)
            {
                GL.DeleteProgram(handle);

                disposedValue = true;
            }
        }

        ~Shader()
        {
            if (disposedValue == false)
            {
                Console.WriteLine("GPU Resource leak! Did you forget to call Dispose()?");
            }
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }
    }
}