using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UIElements;

#if ENABLE_INPUT_SYSTEM && UNITY_INPUT_SYSTEM_PACKAGE
using UnityEngine.InputSystem;
#endif

namespace MuHua
{
    /// <summary>
    /// 悬浮窗口
    /// </summary>
    public abstract class UIFloatingWindow
    {
        /// <summary> 绑定的元素 </summary>
        public readonly VisualElement element;
        /// <summary> 绑定的画布 </summary>
        public readonly VisualElement canvas;

        private bool isDownMove;
        private Vector3 pointerPosition;
        private Vector3 originalPosition;

        public VisualElement Window => element.Q<VisualElement>("Window");
        public VisualElement Top => element.Q<VisualElement>("Top");
        public VisualElement Container => element.Q<VisualElement>("Container");

        public Label Title => element.Q<Label>("Title");
        public Button Close => element.Q<Button>("Close");

        public UIFloatingWindow(VisualElement element, VisualElement canvas)
        {
            this.element = element;
            this.canvas = canvas;

            Top.RegisterCallback<PointerDownEvent>(TopDown);
            canvas.RegisterCallback<PointerUpEvent>((evt) => isDownMove = false);
            canvas.RegisterCallback<PointerLeaveEvent>((evt) => isDownMove = false);

            Close.clicked += () => { SetActive(false); };
        }

        /// <summary> 按下Top </summary>
        private void TopDown(PointerDownEvent evt)
        {
            isDownMove = true;
            pointerPosition = UITool.GetMousePosition();
            originalPosition = Window.transform.position;
        }

        /// <summary> 设置活动状态 </summary>
        public virtual void SetActive(bool active)
        {
            Window.EnableInClassList("window-hidden", !active);
        }

        /// <summary> 更新状态 </summary>
        public virtual void Update()
        {
            if (!isDownMove) { return; }
            Vector3 mousePosition = UITool.GetMousePosition();
            Vector3 offset = mousePosition - pointerPosition;
            Vector3 position = originalPosition + new Vector3(offset.x, -offset.y);

            float width = canvas.resolvedStyle.width - Window.resolvedStyle.width;
            float height = canvas.resolvedStyle.height - Window.resolvedStyle.height;
            position.x = Mathf.Clamp(position.x, 0, width);
            position.y = Mathf.Clamp(position.y, 0, height);

            Window.transform.position = position;
        }

    }
}