using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using OpenTK;
using OpenTK.Graphics.OpenGL;
using Wicked.Engine;

namespace Wicked.Shaders
{
    public class Shader
    {
        private int _handle;

        public Shader CompileShader(ShaderObject[] shaders)
        {
            int status = -1;
            string info = "";

            List<int> compiled = new List<int>();

            foreach (var shader in shaders)
            {
                var index = GL.CreateShader(shader.ShaderInformation);
                GL.ShaderSource(index, shader.ShaderCode);
                GL.CompileShader(index);

                GL.GetShaderInfoLog(index, out info);
                GL.GetShader(index, ShaderParameter.CompileStatus, out status);

                if (status != 1)
                    throw new ApplicationException(info);

                compiled.Add(index);
            }

            _handle = GL.CreateProgram();

            foreach (var shader in compiled) { GL.AttachShader(_handle, shader); }

            GL.LinkProgram(_handle);

            foreach (var shader in compiled)
            {
                GL.DetachShader(_handle, shader);
                GL.DeleteShader(shader);
            }

            return this;
        }


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


        public void SetInt(string name, int value)
        {
            int location = GL.GetUniformLocation(_handle, name);

            if (location == -1)
            {
                throw new ArgumentException("uniform name not found");
            }

            GL.Uniform1(location, value);
        }


        public void SetMatrix4(string name, Matrix4 matrix)
        {
            int location = GL.GetUniformLocation(_handle, name);

            if (location == -1)
            {
                throw new ArgumentException("uniform name not found");
            }

            GL.UniformMatrix4(location, true, ref matrix);
        }


        public int GetAttribLocation(string attribName)
        {
            return GL.GetAttribLocation(_handle, attribName);
        }
    }
}