/*
The MIT License

Copyright (c) 2009-2010 Carlos Guzmán Álvarez

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;

namespace Chronos.Presentation.DragAndDrop
{
    public sealed class DragDropManager
    {
        #region · Singleton Instance ·

        public static readonly DragDropManager Instance = new DragDropManager();

        #endregion

        #region · Attached Properties ·

        /// <summary>
        /// Identifies the IsDesktopCanvas dependency property.
        /// </summary>
        public static readonly DependencyProperty IsDropTargetProperty =
            DependencyProperty.RegisterAttached("IsDropTarget", typeof(bool), typeof(DragDropManager),
                new FrameworkPropertyMetadata(false,
                    new PropertyChangedCallback(OnIsDropTarget)));

        /// <summary>
        /// Identifies the IsDragSource dependency property.
        /// </summary>
        public static readonly DependencyProperty IsDragSourceProperty =
            DependencyProperty.RegisterAttached("IsDragSource", typeof(bool), typeof(DragDropManager),
                new FrameworkPropertyMetadata(false,
                    new PropertyChangedCallback(OnIsDragSource)));

        #endregion

        #region · Dependency Property Get/Set Methods ·

        /// <summary>
        /// Gets the value of the IsDropTarget attached property
        /// </summary>
        /// <param name="d"></param>
        /// <returns></returns>
        public static bool GetIsDropTarget(DependencyObject d)
        {
            return (bool)d.GetValue(IsDropTargetProperty);
        }

        /// <summary>
        /// Sets the value of the IsDropTarget attached property
        /// </summary>
        /// <param name="d"></param>
        /// <param name="value"></param>
        public static void SetIsDropTarget(DependencyObject d, bool value)
        {
            d.SetValue(IsDropTargetProperty, value);
        }

        /// <summary>
        /// Gets the value of the IsDragSource attached property
        /// </summary>
        /// <param name="d"></param>
        /// <returns></returns>
        public static bool GetIsDragSource(DependencyObject d)
        {
            return (bool)d.GetValue(IsDragSourceProperty);
        }

        /// <summary>
        /// Sets the value of the IsDragSource attached property
        /// </summary>
        /// <param name="d"></param>
        /// <param name="value"></param>
        public static void SetIsDragSource(DependencyObject d, bool value)
        {
            d.SetValue(IsDragSourceProperty, value);
        }

        #endregion

        #region · Dependency Property Callbacks ·

        private static void OnIsDropTarget(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            FrameworkElement element = d as FrameworkElement;

            if (element != null)
            {
                DragDropManager.Instance.AttachDropTarget(element);
            }
        }

        private static void OnIsDragSource(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            FrameworkElement element = d as FrameworkElement;

            if (element != null)
            {
                DragDropManager.Instance.AttachDragSource(element);
            }
        }

        #endregion

        #region · Fields ·

        private Dictionary<FrameworkElement, DropHelper> dropTargets;
        private Dictionary<FrameworkElement, DragHelper> dragSources;

        #endregion

        #region · Constructors ·

        private DragDropManager()
        {
            this.dropTargets = new Dictionary<FrameworkElement, DropHelper>();
            this.dragSources = new Dictionary<FrameworkElement, DragHelper>();
        }

        #endregion

        #region · Private Methods ·

        private void AttachDropTarget(FrameworkElement element)
        {
            if (!this.dropTargets.ContainsKey(element))
            {
                element.Unloaded += new RoutedEventHandler(DragDropManager_Unloaded);
                this.dropTargets.Add(element, new DropHelper(element));
            }
        }

        private void AttachDragSource(FrameworkElement element)
        {
            if (!this.dragSources.ContainsKey(element))
            {
                element.Unloaded += new RoutedEventHandler(DragDropManager_Unloaded);

                if (element is ListBox)
                {
                    this.dragSources.Add(element, new DragHelper(element, new ListBoxDragDropDataProvider(element as ListBox), null));
                }
                else if (element is TreeView)
                {
                    this.dragSources.Add(element, new DragHelper(element, new TreeViewDragDropDataProvider(element as TreeView), null));
                }
            }
        }

        #endregion

        #region · Event Handlers ·

        private void DragDropManager_Unloaded(object sender, RoutedEventArgs e)
        {
            (sender as FrameworkElement).Unloaded -= new RoutedEventHandler(DragDropManager_Unloaded);
                            
            if (this.dragSources.ContainsKey(sender as FrameworkElement))
            {
                this.dragSources.Remove(sender as FrameworkElement);
            }
            else if (this.dropTargets.ContainsKey(sender as FrameworkElement))
            {
                this.dropTargets.Remove(sender as FrameworkElement);
            }
        }

        #endregion
    }
}