namespace Yw.WpfUI.Hydro
{
    /// <summary>
    /// 绘制选择辅助类
    /// </summary>
    internal class DrawSelectionHelper : IDisposable
    {
        /// <summary>
        /// 
        /// </summary>
        public DrawSelectionHelper
            (
                HelixViewport3D viewport,
                DrawInitialHelper initialHelper
            )
        {
            _viewport = viewport;
            _initialHelper = initialHelper;
            Attach();
        }



        /// <summary>
        /// 选择改变事件
        /// </summary>
        public event Action<List<VisualDraw3D>> SelectionChangedEvent;


        private readonly HelixViewport3D _viewport = null;//三维组件
        private readonly DrawInitialHelper _initialHelper = null;//初始化辅助类
        private VisualStateObject _stateObject = null;//状态对象
        private List<VisualDraw3D> _selection = new();//选择集合

        /// <summary>
        /// 选择集合
        /// </summary>
        public List<VisualDraw3D> Selection
        {
            get { return _selection; }
            private set { _selection = value; }
        }

        /// <summary>
        /// 是否启用
        /// </summary>
        public bool Enabled
        {
            get { return _enabled; }
            set { _enabled = value; }
        }
        private bool _enabled = true;

        /// <summary>
        /// 是否初始化
        /// </summary>
        public bool Initialized
        {
            get { return _initialized; }
            private set { _initialized = value; }
        }
        private bool _initialized = false;

        //初始化
        private void Initialize()
        {
            if (!_initialHelper.Initialized)
            {
                return;
            }
            if (_stateObject == null)
            {
                _stateObject = new VisualStateObject();
                _stateObject.HtmlColor = Yw.Settings.HydroL3dParasHelper.HydroL3d.Selection.HtmlColor;
                _stateObject.Opacity = Yw.Settings.HydroL3dParasHelper.HydroL3d.Selection.Opacity;
                _stateObject.Scale = Yw.Settings.HydroL3dParasHelper.HydroL3d.Selection.Scale;
                _stateObject.Visible = Yw.Settings.HydroL3dParasHelper.HydroL3d.Selection.Visible;
            }
            _initialized = true;
        }

        //处理初始化完成
        private void OnInitialCompleted()
        {
            Initialize();
        }

        //处理鼠标弹起
        private void OnMouseUp(object sender, MouseButtonEventArgs e)
        {
            if (e.ChangedButton == MouseButton.Left)
            {
                var pt = e.GetPosition(_viewport);
                Handle(pt);
            }
        }


        #region 内部实现

        //添加选择
        private void AddToSelection(VisualDraw3D visual3d)
        {
            if (_selection.Contains(visual3d))
            {
                return;
            }
            _selection.Add(visual3d);
            visual3d.LoadState(eVisualState.Selection, _stateObject);
            visual3d.UpdateVisual3D();
        }

        //从选择中移除
        private void RemoveFromSelection(VisualDraw3D visual3d)
        {
            if (!_selection.Contains(visual3d))
            {
                return;
            }
            _selection.Remove(visual3d);
            visual3d.UnloadState(eVisualState.Selection);
            visual3d.UpdateVisual3D();
        }

        //清理选择
        private void ClearSelection()
        {
            if (_selection.Count < 1)
            {
                return;
            }
            _selection.ForEach(x =>
            {
                x.UnloadState(eVisualState.Selection);
                x.UpdateVisual3D();
            });
            _selection.Clear();
        }

        #endregion

        #region 选择处理

        //处理
        private void Handle(Point pt)
        {
            if (!Initialized)
            {
                return;
            }
            if (!Enabled)
            {
                return;
            }
            var visual3d = _viewport.FindNearestVisual(pt) as VisualDraw3D;
            if (visual3d == null)
            {
                if (_selection.Count > 0)
                {
                    ClearSelection();
                    this.SelectionChangedEvent?.Invoke(null);
                }
                return;
            }

            if (_selection.Count == 1 && _selection[0] == visual3d)
            {
                return;
            }
            ClearSelection();
            AddToSelection(visual3d);
            this.SelectionChangedEvent?.Invoke(_selection);
        }

        //附加
        private void Append(Point pt)
        {
            if (!Initialized)
            {
                return;
            }
            if (!Enabled)
            {
                return;
            }
            var visual3d = _viewport.FindNearestVisual(pt) as VisualDraw3D;
            if (visual3d == null)
            {
                return;
            }
            if (_selection.Contains(visual3d))
            {
                return;
            }
            AddToSelection(visual3d);
            this.SelectionChangedEvent?.Invoke(_selection);
        }

        #endregion

        #region 外部选择

        /// <summary>
        /// 选择Visual
        /// 不触发选择改变事件
        /// </summary>
        public void SelectVisual(VisualDraw3D visual)
        {
            ClearSelection();
            if (visual == null)
            {
                return;
            }
            AddToSelection(visual);
        }

        /// <summary>
        /// 选择Visuals
        /// </summary>
        public void SelectVisual(List<VisualDraw3D> visuals)
        {
            ClearSelection();
            if (visuals == null || visuals.Count < 1)
            {
                return;
            }
            visuals.ForEach(AddToSelection);
        }

        #endregion


        //附加
        private void Attach()
        {
            _viewport.MouseUp += OnMouseUp;
            _initialHelper.InitialCompletedEvent += OnInitialCompleted;
        }

        //分离
        private void Detach()
        {
            _viewport.MouseUp -= OnMouseUp;
            _initialHelper.InitialCompletedEvent -= OnInitialCompleted;
        }

        /// <summary>
        /// 释放
        /// </summary>
        public void Dispose()
        {
            Detach();
        }

    }
}