using AppUI.Manager.View;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

namespace AppUI.Manager
{
    /// <summary>
    /// AppUI UI 根节点：创建 Canvas、默认分组 "0"，以及按需克隆出的上层分组（如 "1"）。
    /// 预制体与页面逻辑见 <see cref="View.ViewManager"/>。
    /// </summary>
    public class ViewMgr : MonoBehaviour
    {
        const string DefaultGroupName = "0";

        static ViewMgr s_Instance;
        static bool s_SceneHookRegistered;

        public static ViewMgr Instance
        {
            get
            {
                if (s_Instance == null)
                {
                    var go = new GameObject(nameof(ViewMgr));
                    s_Instance = go.AddComponent<ViewMgr>();
                    DontDestroyOnLoad(go);
                    s_Instance.SetupRoot();
                }

                return s_Instance;
            }
        }

        public static bool HasInstance() => s_Instance != null;

        /// <summary>
        /// 初始化 UI 根节点，并确保红外等上层分组 "1" 已创建（仅需在 Home 场景入口调用一次）。
        /// </summary>
        public static void EnsureInitialized()
        {
            _ = Instance;
            EnsureGroup(1);
        }

        /// <summary>
        /// 获取或创建指定分组节点；groupIndex 为 0 时返回默认全屏分组。
        /// </summary>
        public static Transform EnsureGroup(int groupIndex)
        {
            _ = Instance;
            string groupName = groupIndex.ToString();
            Transform existing = Instance.transform.Find(groupName);
            if (existing)
                return existing;

            if (groupIndex == 0)
            {
                Instance.CreateDefaultGroup();
                return Instance.transform.Find(DefaultGroupName);
            }

            Transform template = Instance.transform.Find(DefaultGroupName);
            if (!template)
            {
                Instance.CreateDefaultGroup();
                template = Instance.transform.Find(DefaultGroupName);
            }

            return Instance.CreateGroupFromTemplate(template, groupIndex);
        }

        void OnDestroy()
        {
            if (s_SceneHookRegistered)
            {
                SceneManager.sceneUnloaded -= OnSceneUnloaded;
                s_SceneHookRegistered = false;
            }

            if (s_Instance == this)
                s_Instance = null;
        }

        static void EnsureSceneHook()
        {
            if (s_SceneHookRegistered)
                return;
            s_SceneHookRegistered = true;
            SceneManager.sceneUnloaded += OnSceneUnloaded;
        }

        static void OnSceneUnloaded(Scene scene)
        {
            ViewManager.HideAllView();

            if (scene.name == "InfraredGameDouble" || scene.name == "WildAttackDouble")
            {
                InfraredDemo._ins?.SetSinglePoint(true);
                Debug.Log("OnSceneUnloaded 取消设置单点模式");
            }
        }

        void SetupRoot()
        {
            gameObject.layer = LayerMask.NameToLayer("UI");
            Canvas viewCanvas = gameObject.AddComponent<Canvas>();
            viewCanvas.renderMode = RenderMode.ScreenSpaceOverlay;
            viewCanvas.sortingOrder = 1;

            CanvasScaler viewMgrCanvasScaler = gameObject.AddComponent<CanvasScaler>();
            viewMgrCanvasScaler.uiScaleMode = CanvasScaler.ScaleMode.ScaleWithScreenSize;
            viewMgrCanvasScaler.referenceResolution = new Vector2(2532, 1170);
            viewMgrCanvasScaler.screenMatchMode = CanvasScaler.ScreenMatchMode.MatchWidthOrHeight;
            viewMgrCanvasScaler.matchWidthOrHeight = 0f;

            gameObject.AddComponent<GraphicRaycaster>();

            CreateDefaultGroup();
            EnsureSceneHook();
        }

        void CreateDefaultGroup()
        {
            if (transform.Find(DefaultGroupName))
                return;

            var rectTransform = new GameObject(DefaultGroupName).AddComponent<RectTransform>();
            rectTransform.gameObject.layer = LayerMask.NameToLayer("UI");
            rectTransform.SetParent(transform);
            rectTransform.localPosition = Vector3.zero;
            rectTransform.localScale = Vector3.one;
            rectTransform.anchorMin = Vector2.zero;
            rectTransform.anchorMax = Vector2.one;
            rectTransform.offsetMin = Vector2.zero;
            rectTransform.offsetMax = Vector2.zero;
        }

        Transform CreateGroupFromTemplate(Transform template, int groupIndex)
        {
            string groupName = groupIndex.ToString();
            var newObj = new GameObject(groupName);
            newObj.layer = LayerMask.NameToLayer("UI");
            newObj.transform.SetParent(transform);
            newObj.transform.localPosition = template.localPosition;
            newObj.transform.localRotation = template.localRotation;
            newObj.transform.localScale = template.localScale;

            RectTransform rectTransform = newObj.AddComponent<RectTransform>();
            if (template is RectTransform templateRect)
            {
                rectTransform.anchorMin = templateRect.anchorMin;
                rectTransform.anchorMax = templateRect.anchorMax;
                rectTransform.offsetMin = templateRect.offsetMin;
                rectTransform.offsetMax = templateRect.offsetMax;
            }

            for (int i = 0; i < transform.childCount - 1; i++)
            {
                if (!int.TryParse(transform.GetChild(i).gameObject.name, out int siblingIndex))
                    continue;
                if (groupIndex < siblingIndex)
                {
                    rectTransform.SetSiblingIndex(i);
                    break;
                }
            }

            return rectTransform;
        }
    }
}