namespace Guru.UI
{
    using System;
    using UnityEngine;
    using UnityEngine.UI;
    
    public class UIRoot : ViewBase
    {
        const string PrefabPath = "guru/ui/root_canvas";
        private static UIRoot _instance;
        public static UIRoot Instance
        {
            get
            {
                if (_instance == null) _instance = LoadInstance();
                return _instance;   
            }
        }

        
        
        /// <summary>
        /// CloneObject 对象
        /// </summary>
        /// <returns></returns>
        private static UIRoot LoadInstance()
        {
            var ui = CloneResources<UIRoot>(PrefabPath);
            ui.Init();
            return ui;
        }


        public static T Clone<T>(GameObject prefab, Transform container = null) where T :Component
        {
            var go = Instantiate(prefab, container);
            if (go != null)
            {
                go.name = nameof(T).ToLower();
                return go.GetComponent<T>();
            }
            return null;
        }

        public static T CloneResources<T>(string path, Transform container = null) where T : Component
        {
            var prefab = Resources.Load<GameObject>(path);
            if( null != prefab) return Clone<T>(prefab, container);
            return null;
        }
        
        
        
        private Canvas _canvas;
        private CanvasScaler _canvasScaler;
        private Transform _rootNode;
        
        

        private void Init()
        {
            DontDestroyOnLoad(gameObject);
            gameObject.name = "guru_ui";
            _rootNode = CreateEmptyNode("root");

            _canvas = gameObject.GetComponent<Canvas>();
            _canvasScaler = gameObject.GetComponent<CanvasScaler>();
        }



     

        
        /// <summary>
        /// 引用分辨率
        /// </summary>
        public Vector2 ReferenceResolution
        {
            get => _canvasScaler.referenceResolution;
            set => _canvasScaler.referenceResolution = value;
        }
        
        /// <summary>
        /// 宽高适配
        /// </summary>
        public float MatchWidthOrHeight
        {
            get => _canvasScaler.matchWidthOrHeight;
            set => _canvasScaler.matchWidthOrHeight = value;
        }

        /// <summary>
        /// 屏幕渲染 Order 
        /// </summary>
        public int SortingOrder
        {
            get => _canvas.sortingOrder;
            set => _canvas.sortingOrder = value;
        }



        #region 节点操作

        
        public RectTransform CreateEmptyNode(string nodeName = "node", Transform parent = null)
        {
            if (parent == null) parent = transform;
            var go = new GameObject(nodeName);
            go.transform.SetParent(parent, false);
            go.transform.localScale = Vector3.one;
            var c = go.AddComponent<RectTransform>();
            c.anchorMax = Vector2.one;
            c.anchorMin = Vector2.zero;
            c.sizeDelta = Vector2.zero;
            c.anchoredPosition = Vector2.zero;
            c.pivot = Vector2.one * 0.5f;
            
            return c;
        }


        public RectTransform CreateNodeFromPath(string path, Transform parent = null)
        {
            var names = path.Split('/');
            if (parent == null) parent = _rootNode;
            var node = parent as RectTransform;
            foreach (var n in names)
            {
                node = CreateEmptyNode(n, node);
            }
            return node;
        }


        #endregion
        

    }
}