using System;
using OpenTK.Graphics.OpenGL;
using RecrownedGTK.Graphics.Render.Shader;
namespace RecrownedGTK.Graphics {
    public class VertexAttributesHandle : IDisposable {
        private bool disposed;
        private int handle;
        private bool begun;
        public VertexAttributesHandle() {
            handle = GL.GenVertexArray();
        }

        public void Begin() {
            if (begun) throw new InvalidOperationException("The VertexArrayHandle has already been started.");
            GL.BindVertexArray(handle);
            begun = true;
        }
        public void End() {
            if (!begun) throw new InvalidOperationException("The VertexArrayHandle has never been started.");
            GL.BindVertexArray(0);
            begun = false;
        }

        /// <summary>
        /// Creates a basic vertex attributes object handle that takes in vertices, texture coordinates, and a color.
        /// </summary>
        /// <param name="shader">The shader program used. Default is the one created from <see cref="RecrownedGTK.Graphics.Render.Shader.Shader.CreateBasicShader"/>.</param>
        /// <param name="positionAttribName">The name of the attribute for the vertex's position in the shader. Default is "aPosition".</param>
        /// <param name="textureAttribName">The name of the attribute for the texture's coordinate. Default is "aTexture".</param>
        /// <param name="colorAttribName">The name of the attribute for color mixture. Default is "aColor".</param>
        /// <returns>The built <see cref="RecrownedGTK.Graphics.VertexAttributesHandle"/>.</returns>
        public static VertexAttributesHandle CreateBasicVA(Shader shader = null, string positionAttribName = "aPosition", string textureAttribName = "aTexture", string colorAttribName = "aColor") {
            if (shader == null) shader = Shader.CreateBasicShader();
            VertexAttributesHandle vertexAttribs = new VertexAttributesHandle();
            GL.VertexAttribPointer(shader.GetAttribLocation(positionAttribName), 3, VertexAttribPointerType.Float, false, 9 * sizeof(float), 0);
            GL.VertexAttribPointer(shader.GetAttribLocation(textureAttribName), 2, VertexAttribPointerType.Float, false, 9 * sizeof(float), 3 * sizeof(float));
            GL.VertexAttribPointer(shader.GetAttribLocation(colorAttribName), 4, VertexAttribPointerType.Float, false, 9 * sizeof(float), 5 * sizeof(float));
            vertexAttribs.End();
            return vertexAttribs;
        }
        public void Dispose() {
            Dispose(true);
            GC.SuppressFinalize(this);
        }
        protected virtual void Dispose(bool disposing) {
            if (disposed) return;
            if (disposing) {

            }
            GL.BindVertexArray(0);
            GL.DeleteVertexArray(handle);
            disposed = true;
        }
        ~VertexAttributesHandle() {
            Dispose(false);
        }
    }
}