/*************************************************************************************

   Extended WPF Toolkit

   Copyright (C) 2007-2013 Xceed Software Inc.

   This program is provided to you under the terms of the Microsoft Public
   License (Ms-PL) as published at http://wpftoolkit.codeplex.com/license 

   For more features, controls, and fast professional support,
   pick up the Plus Edition at http://xceed.com/wpf_toolkit

   Stay informed: follow @datagrid on Twitter or Like http://facebook.com/datagrids

  ***********************************************************************************/

using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Media;
using System.Windows.Threading;
using Xceed.Wpf.Toolkit.Core.Utilities;

namespace Xceed.Wpf.Toolkit.Panels
{
  public class SwitchPresenter : FrameworkElement
  {
    #region Constructors

    public SwitchPresenter()
      : base()
    {
      this.AddVisualChild( _contentPresenter );

      this.Loaded += new RoutedEventHandler( this.SwitchPresenter_Loaded );
      this.Unloaded += new RoutedEventHandler( this.SwitchPresenter_Unloaded );
    }

    #endregion

    #region DelaySwitch Property

    // Using a DependencyProperty as the backing store for DelaySwitch.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty DelaySwitchProperty =
      DependencyProperty.Register( "DelaySwitch", typeof( bool ), typeof( SwitchPresenter ), 
        new UIPropertyMetadata( false ) );

    public bool DelaySwitch
    {
      get
      {
        return ( bool )this.GetValue( SwitchPresenter.DelaySwitchProperty );
      }
      set
      {
        this.SetValue( SwitchPresenter.DelaySwitchProperty, value );
      }
    }

    #endregion

    #region DelayPriority Property

    // Using a DependencyProperty as the backing store for DelayPriority.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty DelayPriorityProperty =
      DependencyProperty.Register( "DelayPriority", typeof( DispatcherPriority ), typeof( SwitchPresenter ),
        new UIPropertyMetadata( DispatcherPriority.Background ) );

    public DispatcherPriority DelayPriority
    {
      get
      {
        return ( DispatcherPriority )this.GetValue( SwitchPresenter.DelayPriorityProperty );
      }
      set
      {
        this.SetValue( SwitchPresenter.DelayPriorityProperty, value );
      }
    }

    #endregion

    #region SwitchParent Internal Property

    internal static readonly DependencyProperty SwitchParentProperty =
      DependencyProperty.Register( "SwitchParent", typeof( SwitchPanel ), typeof( SwitchPresenter ),
        new FrameworkPropertyMetadata( null, 
          new PropertyChangedCallback( SwitchPresenter.OnSwitchParentChanged ) ) );

    internal SwitchPanel SwitchParent
    {
      get
      {
        return ( SwitchPanel )this.GetValue( SwitchPresenter.SwitchParentProperty );
      }
      set
      {
        this.SetValue( SwitchPresenter.SwitchParentProperty, value );
      }
    }

    private static void OnSwitchParentChanged( DependencyObject d, DependencyPropertyChangedEventArgs e )
    {
      ( ( SwitchPresenter )d ).OnSwitchParentChanged( e );
    }

    protected virtual void OnSwitchParentChanged( DependencyPropertyChangedEventArgs e )
    {
      if( e.OldValue != null )
      {
        ( e.OldValue as SwitchPanel ).UnregisterPresenter( this, _switchRoot );
        _switchRoot = null;
        BindingOperations.ClearAllBindings( _contentPresenter );
      }

      if( e.NewValue != null )
      {
        _contentPresenter.SetBinding( ContentPresenter.ContentProperty, new Binding() );
        _switchRoot = ( e.NewValue as SwitchPanel ).RegisterPresenter( this );
      }
    }

    private static void OnLoaded( object sender, RoutedEventArgs e )
    {
      SwitchPresenter sp = sender as SwitchPresenter;
      if( sp._switchRoot == null )
      {
        sp.SwitchParent = VisualTreeHelperEx.FindAncestorByType( sp, typeof( SwitchPanel ), false ) as SwitchPanel;
      }
    }

    private static void OnUnloaded( object sender, RoutedEventArgs e )
    {
      ( sender as SwitchPresenter ).SwitchParent = null;
    }

    #endregion

    #region VisualChildrenCount Protected Property

    protected override int VisualChildrenCount
    {
      get
      {
        return 1;
      }
    }

    #endregion

    internal void RegisterID( string id, FrameworkElement element )
    {
      if( element == null )
        return;

      _knownIDs[ id ] = element;
    }

    internal void SwapTheTemplate( DataTemplate template, bool beginAnimation )
    {
      if( this.DelaySwitch )
      {
        _currentTemplate = template;

        this.Dispatcher.BeginInvoke( new Action<DelaySwitchParams>( this.OnSwapTemplate ),
          this.DelayPriority,
          new DelaySwitchParams()
          {
            Template = template,
            BeginAnimation = beginAnimation
          } );
      }
      else
      {
        this.DoSwapTemplate( template, beginAnimation );
      }
    }

    protected override Size MeasureOverride( Size constraint )
    {
      // if first pass, resolve SwitchParent
      if( !_isMeasured && _switchRoot == null )
      {
        SwitchPresenter.OnLoaded( this, null );
        _isMeasured = true;
      }

      _contentPresenter.Measure( constraint );
      return _contentPresenter.DesiredSize;
    }

    protected override Size ArrangeOverride( Size arrangeBounds )
    {
      _contentPresenter.Arrange( new Rect( arrangeBounds ) );
      return arrangeBounds;
    }

    protected override Visual GetVisualChild( int index )
    {
      if( index != 0 )
        throw new ArgumentOutOfRangeException( "index", index, "" );

      return _contentPresenter;
    }

    private void OnSwapTemplate( DelaySwitchParams data )
    {
      // If we are switching the templates fast the invokes will lag. So ignore old invokes.
      if( data.Template == _currentTemplate )
      {
        this.DoSwapTemplate( data.Template, data.BeginAnimation );
        _currentTemplate = null;
      }
    }

    private void DoSwapTemplate( DataTemplate template, bool beginAnimation )
    {
      // cache transforms for known ID'd elements in the current template
      Dictionary<string, Rect> knownLocations = null;
      if( beginAnimation && _knownIDs.Count > 0 )
      {
        knownLocations = new Dictionary<string, Rect>();
        foreach( KeyValuePair<string, FrameworkElement> entry in _knownIDs )
        {
          Size size = entry.Value.RenderSize;
          Matrix m = ( entry.Value.TransformToAncestor( SwitchParent ) as MatrixTransform ).Matrix;
          Point[] points = { new Point(), new Point( size.Width, size.Height ) };
          m.Transform( points );
          knownLocations[ entry.Key ] = new Rect( points[ 0 ], points[ 1 ] );
        }
      }

      // clear the known IDs because the new template will have all new IDs
      _knownIDs.Clear();

      // set and apply the new template
      _contentPresenter.ContentTemplate = template;
      if( template != null )
      {
        _contentPresenter.ApplyTemplate();
      }

      // determine locations of ID'd elements in new template
      // and begin animation to new location
      if( knownLocations != null && _knownIDs.Count > 0 )
      {
        Dictionary<string, Rect> newLocations = null;
        RoutedEventHandler onLoaded = null;
        onLoaded = delegate( object sender, RoutedEventArgs e )
        {
          FrameworkElement element = sender as FrameworkElement;
          element.Loaded -= onLoaded;
          string id = SwitchTemplate.GetID( element );
          if( knownLocations.ContainsKey( id ) )
          {
            // ensure that the new locations have been resolved
            if( newLocations == null )
            {
              newLocations = this.SwitchParent.ActiveLayout.GetNewLocationsBasedOnTargetPlacement( this, _switchRoot );
            }

            UIElement parent = VisualTreeHelper.GetParent( element ) as UIElement;
            if( parent != null )
            {
              Rect previousLocation = knownLocations[ id ];
              Point[] points = { previousLocation.TopLeft, previousLocation.BottomRight };
              Matrix m = ( SwitchParent.TransformToDescendant( parent ) as MatrixTransform ).Matrix;
              m.Transform( points );
              Rect oldLocation = new Rect( points[ 0 ], points[ 1 ] );
              Rect newLocation = newLocations[ id ];
              this.SwitchParent.ActiveLayout.BeginGrandchildAnimation( element, oldLocation, newLocation );
            }
          }
        };

        foreach( KeyValuePair<string, FrameworkElement> entry in _knownIDs )
        {
          entry.Value.Loaded += onLoaded;
        }
      }
    }

    private void SwitchPresenter_Unloaded( object sender, RoutedEventArgs e )
    {
      this.SwitchParent = null;
    }

    private void SwitchPresenter_Loaded( object sender, RoutedEventArgs e )
    {
      if( _switchRoot == null )
      {
        this.SwitchParent = VisualTreeHelperEx.FindAncestorByType( this, typeof( SwitchPanel ), false ) as SwitchPanel;
      }
    }

    #region Private Fields

    // track our topmost ancestor that is the direct child of the SwitchPanel
    internal UIElement _switchRoot = null;
    internal Dictionary<string, FrameworkElement> _knownIDs = new Dictionary<string, FrameworkElement>();

    private ContentPresenter _contentPresenter = new ContentPresenter();
    private bool _isMeasured = false;

    private DataTemplate _currentTemplate;

    #endregion

    #region DelaySwitchParams Nested Type

    private struct DelaySwitchParams
    {
      public DataTemplate Template;
      public bool BeginAnimation;
    }

    #endregion
  }
}