using System;
using System.Collections;
using System.Collections.Generic;
using OpenTK;
using OpenTK.Graphics;
using OpenTK.Graphics.OpenGL4;
using SM.Base.Objects;
using SM.OGL.Mesh;

namespace SM2D.Object
{
    public class Polygon : Mesh
    {
        public override VBO Vertex { get; } = new VBO();
        public override VBO UVs { get; } = new VBO(pointerSize:2);
        public override VBO Color { get; } = new VBO(pointerSize: 4);

        public override PrimitiveType PrimitiveType { get; } = PrimitiveType.TriangleFan;



        public Polygon(ICollection<Vector2> vertices)
        {
            foreach (Vector2 vertex in vertices)
            {
                Color.Add(Color4.White);
                AddVertex(vertex);
            }

            foreach (Vector2 vertex in vertices)
            {
                AddUV(vertex);
            }
        }

        public Polygon(ICollection<PolygonVertex> vertices)
        {
            foreach (PolygonVertex polygonVertex in vertices)
            {
                Color.Add(polygonVertex.Color);
                AddVertex(polygonVertex.Vertex);
            }

            foreach (PolygonVertex vertex in vertices)
            {
                AddUV(vertex.Vertex);
            }
        }

        private void AddVertex(Vector2 vertex)
        {
            BoundingBox.Update(vertex);
            Vertex.Add(vertex, 0);
        }

        private void AddUV(Vector2 vertex)
        {
            Vector2 uv = Vector2.Divide(vertex, BoundingBox.Max.Xy) + BoundingBox.Min.Xy;
            UVs.Add(uv);
        }

        public static Polygon GenerateCircle(int secments = 32)
        {
            List<Vector2> vertices = new List<Vector2>() {Vector2.Zero};

            float step = 360f / secments;
            for (int i = 0; i < secments + 1; i++)
            {
                Vector2 vertex = new Vector2( 0.5f * (float)Math.Cos(step * i * Math.PI / 180f), 0.5f * (float)Math.Sin(step * i * Math.PI / 180f));
                vertices.Add(vertex);
            }

            return new Polygon(vertices);
        }
    }
}