using System.Collections.Generic;
using UnityEngine;

namespace InfinityCode.OnlineMapsSupport
{
    public class TilesetSmoothNormals : MonoBehaviour
    {
        public OnlineMapsTileSetControl control;

        private void Start()
        {
            if (control == null) control = OnlineMapsTileSetControl.instance;
            control.OnMeshUpdated += OnMeshUpdated;
        }

        private void OnMeshUpdated()
        {
            Mesh mesh = control.meshFilter.sharedMesh;
            mesh.RecalculateNormals();

            Vector3[] vertices = mesh.vertices;
            Vector3[] normals = mesh.normals;

            Dictionary<int, Item> items = new Dictionary<int, Item>();

            for (int i = 0; i < vertices.Length; i++)
            {
                Vector3 vertex = vertices[i];
                int hash = vertex.GetHashCode();
                Item item = null;
                if (!items.TryGetValue(hash, out item))
                {
                    item = new Item();
                    items[hash] = item;
                }

                item.Add(i, normals[i]);
            }

            foreach (KeyValuePair<int, Item> pair in items)
            {
                Item item = pair.Value;
                item.FixNormals(normals);
            }

            mesh.normals = normals;
            control.meshFilter.sharedMesh = mesh;
        }

        internal class Item
        {
            public List<int> indices;
            private Vector3 sumOfNormals;

            public Item()
            {
                indices = new List<int>();
            }

            public void Add(int index, Vector3 normal)
            {
                indices.Add(index);
                sumOfNormals += normal;
            }

            public void FixNormals(Vector3[] normals)
            {
                Vector3 normal = (sumOfNormals / indices.Count).normalized;
                for (int i = 0; i < indices.Count; i++)
                {
                    int index = indices[i];
                    normals[index] = normal;
                }
            }
        }
    }
}