BasicTemplateProvider loading fix

BasicTemplateProvider.cs

// Copyright (c) Improbable Worlds Ltd, All Rights Reserved

using System;
using System.Linq;
using Improbable.Assets;
using Improbable.Unity;
using Improbable.Unity.Assets;
using Improbable.Unity.Entity;
using UnityEngine;

namespace Improbable.MinimalBuildSystem.Prefabs
{
    public class BasicTemplateProvider : MonoBehaviour, IEntityTemplateProvider
    {
        [SerializeField]
        private WorkerPlatform platform;

        // The template provider can't be instantiated during construction as Application.isEditor doesn't work.
        private IEntityTemplateProvider templateProvider;

        private IEntityTemplateProvider TemplateProvider
        {
            get
            {
                if (templateProvider == null)
                {
                    var gameObjectLoader = InitializeAssetLoader();
                    templateProvider = InitializeTemplateProvider(gameObjectLoader);
                }

                return templateProvider;
            }
        }

        private IAssetLoader<GameObject> InitializeAssetLoader()
        {
            return new ResourceGameObjectLoader();
        }

        private IEntityTemplateProvider InitializeTemplateProvider(IAssetLoader<GameObject> gameObjectLoader)
        {
            return new AssetDatabaseTemplateProvider(new CachingAssetDatabase(gameObjectLoader));
        }

        public void PrepareTemplate(string prefabName, Action<string> onSuccess, Action<Exception> onError)
        {
            TemplateProvider.PrepareTemplate(prefabName, onSuccess, onError);
        }

        public GameObject GetEntityTemplate(string prefabName)
        {
            return TemplateProvider.GetEntityTemplate(prefabName);
        }

        public void CancelAllTemplatePreparations()
        {
            TemplateProvider.CancelAllTemplatePreparations();
        }

#if UNITY_EDITOR
        [UnityEditor.InitializeOnLoadMethod]
        static void SetupPlaymodeCallbacks()
        {
            UnityEditor.EditorApplication.playModeStateChanged += PrepareEntityPrefabs;

            // Safety check
            UnityEditor.SceneManagement.EditorSceneManager.sceneOpened += (scene, mode) =>
            {
                var provider = FindObjectOfType<BasicTemplateProvider>();
                if (provider != null) {
                    var workerPlatform = provider.platform;
                    if (workerPlatform == 0)
                    {
                        Debug.LogWarning("The BasicTemplateProvider instance has an invalid WorkerPlatform set.", provider);
                    }
                }
            };
        }

        private static void PrepareEntityPrefabs(UnityEditor.PlayModeStateChange state)
        {
            // Only do this when we go from edit mode to play mode
            if (state != UnityEditor.PlayModeStateChange.ExitingEditMode)
            {
                return;
            }

            // Get worker platform
            var workerPlatform = FindObjectOfType<BasicTemplateProvider>().platform;
            Debug.LogFormat("Preparing EntityPrefabs for {0}", workerPlatform.ToString());

            // Find editor method to start export
            const string entityPrefabsTypeName = "Improbable.Unity.MinimalBuildSystem.EntityPrefabs";
            var entityPrefabsType = (from assembly in AppDomain.CurrentDomain.GetAssemblies()
                                     from type in assembly.GetTypes()
                                     where type.FullName == entityPrefabsTypeName
                                     select type).First();

            // Start prefab export
            var method = entityPrefabsType.GetMethod("Export");
            method.Invoke(null, new object[] { workerPlatform });
        }
#endif
    }
}