using OpenTK.Graphics.OpenGL4;

namespace Voxel
{
    static class Renderer
    {
        private static int _ssbo;
        private static int _vao;
        private static List<FaceData> _faces = new List<FaceData>();
        private static Shader _shader;
        private static bool _needsUpdate = false;

        public static void OnLoad()
        {
            string vertexPath = "Shaders/shader.vert";
            string fragmentPath = "Shaders/shader.frag";
            _shader = new Shader(vertexPath, fragmentPath);

            _ssbo = GL.GenBuffer();
            _vao = GL.GenVertexArray();

            GL.BindVertexArray(_vao);
            GL.BindBuffer(BufferTarget.ShaderStorageBuffer, _ssbo);
            GL.BindBufferBase(BufferRangeTarget.ShaderStorageBuffer, 0, _ssbo);
        }

        public static void Render()
        {
            GL.BindVertexArray(_vao);
            GL.BindBuffer(BufferTarget.ShaderStorageBuffer, _ssbo);

            if (_needsUpdate)
            {
                _needsUpdate = false;
                Console.WriteLine("Update buffer");
                uint[] data = _faces.SelectMany(f => f.Pack()).ToArray();
                GL.BufferData(BufferTarget.ShaderStorageBuffer, data.Length * sizeof(uint), data, BufferUsageHint.StaticRead);
            }

            _shader.Use();
            _shader.SetMatrix4("view", Camera.view);
            _shader.SetMatrix4("projection", Camera.projection);

            GL.DrawArrays(PrimitiveType.Triangles, 0, _faces.Count * 6);

            //Console.WriteLine("Rendered " + _faces.Count.ToString() + " faces");
        }

        public static void AddFaces(List<FaceData> faces)
        {
            _faces.AddRange(faces);
            _needsUpdate = true;
        }
    }
}