Fabric

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using UnityEngine;

namespace TankDemo.Model
{
    /// <summary>
    /// Main basic pattern class - 'Factory'
    /// Author: Boris Kotlyar
    /// </summary>
    public static class Factory
    {
        // cached types
        private static Dictionary<string, Type> _entitiesByName;
        private static bool IsInitialized => _entitiesByName != null;

        private static void Init()
        {
            // if already initialized, just skip
            if (IsInitialized)
                return;

            // get all entities
            var entitiesTypes = Assembly.GetAssembly(typeof(Entity)).GetTypes().Where(myType =>
                myType.IsClass && !myType.IsAbstract && myType.IsSubclassOf(typeof(Entity)));

            // dictionary for finding these by name later
            _entitiesByName = new Dictionary<string, Type>();

            // get the names and put them to dictionary
            foreach (var entitiesType in entitiesTypes)
            {
                _entitiesByName.Add(entitiesType.Name, entitiesType);
            }
        }

        /// <summary>
        /// Return component from MonoBehaviour
        /// </summary>
        /// <param name="obj">MonoBehaviour</param>
        /// <param name="entityName">entity combonent based class type</param>
        /// <returns></returns>
        public static Entity GetComponentEntity(GameObject obj, string entityName)
        {
            Init();

            if (_entitiesByName.ContainsKey(entityName))
            {
                var entity = obj.AddComponent(_entitiesByName[entityName]) as Entity;
                return entity;
            }

            return null;
        }

        /// <summary>
        /// Get model entity
        /// </summary>
        /// <param name="entityName">entity class type</param>
        /// <returns></returns>
        public static Entity GetEntity(string entityName)
        {
            Init();

            if (_entitiesByName.ContainsKey(entityName))
            {
                var type = _entitiesByName[entityName];
                var entity = Activator.CreateInstance(type) as Entity;
                return entity;
            }

            return null;
        }

        /// <summary>
        /// Get all stored entities
        /// </summary>
        /// <returns></returns>
        internal static IEnumerable<string> GetNames()
        {
            Init();
            return _entitiesByName.Keys;
        }
    }
}