using System.Windows;
using System.Windows.Input;
using System.Windows.Documents;

namespace SHJX.Service.WorkFlowEdit
{
    public class InputTool : IInputTool
    {
        protected DiagramView View { get; private set; }
        protected IDiagramController Controller { get { return View.Controller; } }
        protected Point? MouseDownPoint { get; set; }
        protected DiagramItem MouseDownItem { get; set; }

        public InputTool(DiagramView view)
        {
            View = view;
        }

        public virtual void OnMouseDown(MouseButtonEventArgs e)
        {
            MouseDownItem = (e.OriginalSource as DependencyObject).FindParent<DiagramItem>();
            MouseDownPoint = e.GetPosition(View);
            e.Handled = true;
        }

        public virtual void OnMouseMove(MouseEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Pressed && MouseDownPoint.HasValue)
            {
                if (MouseDownItem != null)
                {
                    View.DragTool.BeginDrag(MouseDownPoint.Value, MouseDownItem, DragThumbKinds.Center);
                }
                else
                {
                    View.Selection.Clear();
                    View.DragAdorner = CreateRubberbandAdorner();
                }
                MouseDownItem = null;
                MouseDownPoint = null;
            }
            e.Handled = true;
        }

        public virtual void OnMouseUp(MouseButtonEventArgs e)
        {
            if (MouseDownPoint == null)
                return;
            var item = (e.Source as DependencyObject).FindParent<DiagramItem>();
            SelectItem(item);
            e.Handled = true;
        }

        public virtual void OnPreviewKeyDown(KeyEventArgs e)
        {
            if (e.Key == Key.Escape)
            {
                e.Handled = true;
                if (View.DragAdorner != null && View.DragAdorner.IsMouseCaptured)
                    View.DragAdorner.ReleaseMouseCapture();
                else
                    View.Selection.Clear();
            }
        }

        protected virtual void SelectItem(DiagramItem item)
        {
            var sel = View.Selection;
            if (Keyboard.Modifiers == ModifierKeys.Control)
            {
                if (item != null && item.CanSelect)
                {
                    if (item.IsSelected)
                        sel.Remove(item);
                    else
                        sel.Add(item);
                }
            }
            else if (Keyboard.Modifiers == ModifierKeys.Shift)
            {
                if (item != null && item.CanSelect)
                    sel.Add(item);
            }
            else
            {
                if (item != null && item.CanSelect)
                    sel.Set(item);
                else
                    sel.Clear();
            }
        }

        protected virtual Adorner CreateRubberbandAdorner()
        {
            return new RubberbandAdorner(View, MouseDownPoint.Value);
        }
    }
}