using System.Collections;
using System.Collections.Generic;
using Unity.VisualScripting;
using UnityEngine;

public enum E_UILayer
{
    /// <summary>
    /// 最底层
    /// </summary>
    Bottom,
    /// <summary>
    /// 中层
    /// </summary>
    Middle,
    /// <summary>
    /// 高层
    /// </summary>
    Top,
    /// <summary>
    /// 系统层 最高层
    /// </summary>
    System,
}
public class UIManager
{
    private static UIManager instance = new UIManager();
    public static UIManager Instance => instance;

    //用于存储显示着的面板的 没显示一个面板 就会存入这个字典
    //隐藏面板时 直接获取字典中的对应面板 进行隐藏
    private Dictionary<string, BasePanel> panelDic = new Dictionary<string, BasePanel>();

    //场景中 Canvas对象 用于设置为面板的父对象
    private Transform canvasTrans;

    //层级父对象
    private Transform bottomLayer;
    private Transform middleLayer;
    private Transform topLayer;
    private Transform systemLayer;

    private UIManager()
    {
        //得到场景中的Canvas对象
        GameObject canvas = GameObject.Instantiate(Resources.Load<GameObject>("UI/Canvas"));
        canvasTrans = canvas.transform;
        //通过过场景不移除该对象 保证这个游戏过程中 只有一个 canvas对象
        GameObject.DontDestroyOnLoad(canvas);

        //找到层级父对象
        bottomLayer = canvas.transform.Find("Bottom");
        middleLayer = canvas.transform.Find("Middle");
        topLayer = canvas.transform.Find("Top");
        systemLayer = canvas.transform.Find("System");
    }

    /// <summary>
    /// 获取对应层级的父对象
    /// </summary>
    /// <param name="layer">层级枚举值</param>
    /// <returns></returns>
    public Transform GetLayerFather(E_UILayer layer)
    {
        switch (layer)
        {
            case E_UILayer.Bottom:
                return bottomLayer;
            case E_UILayer.Middle:
                return middleLayer;
            case E_UILayer.Top:
                return topLayer;
            case E_UILayer.System:
                return systemLayer;
            default:
                return null;
        }
    }

    //显示面板
    public T ShowPanel<T>(E_UILayer layer) where T:BasePanel
    {
        //我们只需要保证 泛型T的类型 和面板预设体名字 一样 定一个这样的规则 就可以非常方便的让我们使用了
        string panelName = typeof(T).Name;

        //判断 字典中 是否已经显示了这个面板
        if (panelDic.ContainsKey(panelName))
        {
            return panelDic[panelName] as T;
        }

        //显示面板 根据面板名字 动态的创建预设体 设置父对象
        GameObject panelObj = GameObject.Instantiate(Resources.Load<GameObject>("UI/" + panelName));

        //层级的处理
        Transform father = GetLayerFather(layer);
        //避免没有按指定规则传递层级参数 避免为空
        if (father == null)
            father = middleLayer;
        //把这个对象 放到场景中的Canvas下面
        panelObj.transform.SetParent(father, false);

        //执行面板上 显示逻辑 并且应该把它保存起来
        T panel = panelObj.GetComponent<T>();
        //把这个面板脚本 存储到字典中 方便之后的 获取 和 隐藏
        panelDic.Add(panelName, panel);

        return panel;
    }

    
    /// <summary>
    /// 隐藏面板
    /// </summary>
    /// <typeparam name="T">面板类名</typeparam>
    /// <param name="isFade">是否淡出完毕过后才删除面板 默认是true</param>
    public void HidePanel<T>() where T : BasePanel
    {
        //根据泛型的得到名字
        string panelName = typeof(T).Name;
        //判断当前显示的面板 有没有你想隐藏的
        if (panelDic.ContainsKey(panelName))
        {
            //删除对象
            GameObject.Destroy(panelDic[panelName].gameObject);
            //删除字典里面存储的面板脚本
            panelDic.Remove(panelName);
        }
    }

    //得到面板
    public T GetPanel<T>() where T : BasePanel
    {
        string panelName = typeof(T).Name;
        if (panelDic.ContainsKey(panelName))
        {
            return panelDic[panelName] as T;
        }
        //如果没有对应显示的 就为空
        return null;
    }
}