using System;
using System.Linq;
using UnityEditor;
using UnityEngine;

namespace RoboticWeaselAssault.Gamutmamut.Editor
{
    public class EditorTools
    {
        /// <summary>
        /// Copies a splat map into a mesh's vertex colors. A mesh and a texture must be selected simultaneously.
        /// Read/write must be enabled in the texture's import settings.
        /// </summary>
        [MenuItem("Tools/Copy SplatMap to Vertex Colors")]
        public static void SplatMapToVertexColors()
        {
            var mesh = Selection.objects.OfType<Mesh>().FirstOrDefault();
            var texture = Selection.objects.OfType<Texture2D>().FirstOrDefault();

            if (mesh == null || texture == null)
            {
                throw new Exception("Please select a mesh and a texture.");
            }

            var newMesh = CopyMesh(mesh);
            var colors = new Color[newMesh.vertexCount];
            var uvs = newMesh.uv;
            
            for (var i = 0; i < colors.Length; i++)
            {
                // Get the texture coordinates
                var uv = uvs[i];
                
                // Sample the texture on the given UV position
                colors[i] = texture.GetPixelBilinear(uv.x, uv.y);
            }

            newMesh.colors = colors;

            // Show a UI to get the path where the new mesh should be saved
            string targetPath = EditorUtility.SaveFilePanel("Save mesh", "Assets/", mesh.name, "asset");
            if (targetPath != null)
            {
                AssetDatabase.CreateAsset(newMesh, FileUtil.GetProjectRelativePath(targetPath));
            }
        }

        private static Mesh CopyMesh(Mesh mesh)
        {
            return new Mesh
            {
                vertices = mesh.vertices,
                triangles = mesh.triangles,
                uv = mesh.uv,
                uv2 = mesh.uv2,
                normals = mesh.normals,
                colors = mesh.colors,
                tangents = mesh.tangents
            };
        }
    }
}