using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Reflection;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Controls.Primitives;

using System.Windows.Media;



namespace JelleDruyts.Windows.DragDrop

{

    internal static class ItemsControlExtensions

    {

        public static bool CanSelectMultipleItems(this ItemsControl itemsControl)

        {

            if (itemsControl is MultiSelector)

            {

                // The CanSelectMultipleItems property is protected. Use reflection to

                // get its value anyway.

                return (bool)itemsControl.GetType()

                    .GetProperty("CanSelectMultipleItems", BindingFlags.Instance | BindingFlags.NonPublic)

                    .GetValue(itemsControl, null);

            }

            else if (itemsControl is ListBox)

            {

                return ((ListBox)itemsControl).SelectionMode != SelectionMode.Single;

            }

            else

            {

                return false;

            }

        }



        public static UIElement GetItemContainer(this ItemsControl itemsControl, UIElement child)

        {

            Type itemType = GetItemContainerType(itemsControl);



            if (itemType != null)

            {

                return (UIElement)child.GetVisualAncestor(itemType);

            }



            return null;

        }



        public static UIElement GetItemContainerAt(this ItemsControl itemsControl, Point position)

        {

            IInputElement inputElement = itemsControl.InputHitTest(position);

            UIElement uiElement = inputElement as UIElement;



            if (uiElement != null)

            {

                return GetItemContainer(itemsControl, uiElement);

            }



            return null;

        }



        public static UIElement GetItemContainerAt(this ItemsControl itemsControl, Point position,

                                                   Orientation searchDirection)

        {

            Type itemContainerType = GetItemContainerType(itemsControl);



            if (itemContainerType != null)

            {

                LineGeometry line;



                switch (searchDirection)

                {

                    case Orientation.Horizontal:

                        line = new LineGeometry(new Point(0, position.Y), new Point(itemsControl.RenderSize.Width, position.Y));

                        break;

                    case Orientation.Vertical:

                        line = new LineGeometry(new Point(position.X, 0), new Point(position.X, itemsControl.RenderSize.Height));

                        break;

                    default:

                        throw new ArgumentException("Invalid value for searchDirection");

                }



                List<DependencyObject> hits = new List<DependencyObject>();



                VisualTreeHelper.HitTest(itemsControl, null,

                    result =>

                    {

                        DependencyObject itemContainer = result.VisualHit.GetVisualAncestor(itemContainerType);

                        if (itemContainer != null) hits.Add(itemContainer);

                        return HitTestResultBehavior.Continue;

                    },

                    new GeometryHitTestParameters(line));



                return GetClosest(itemsControl, hits, position, searchDirection);

            }



            return null;

        }



        public static Type GetItemContainerType(this ItemsControl itemsControl)

        {

            // There is no safe way to get the item container type for an ItemsControl. 

            // First hard-code the types for the common ItemsControls.

            if (itemsControl is ListView)

            {

                return typeof(ListViewItem);

            }

            else if (itemsControl is TreeView)

            {

                return typeof(TreeViewItem);

            }

            else if (itemsControl is ListBox)

            {

                return typeof(ListBoxItem);

            }



            // Otherwise look for the control's ItemsPresenter, get it's child panel and the first 

            // child of that *should* be an item container.

            //

            // If the control currently has no items, we're out of luck.

            if (itemsControl.Items.Count > 0)

            {

                IEnumerable<ItemsPresenter> itemsPresenters = itemsControl.GetVisualDescendents<ItemsPresenter>();



                foreach (ItemsPresenter itemsPresenter in itemsPresenters)

                {

                    DependencyObject panel = VisualTreeHelper.GetChild(itemsPresenter, 0);

                    DependencyObject itemContainer = VisualTreeHelper.GetChild(panel, 0);



                    // Ensure that this actually *is* an item container by checking it with

                    // ItemContainerGenerator.

                    if (itemContainer != null &&

                        itemsControl.ItemContainerGenerator.IndexFromContainer(itemContainer) != -1)

                    {

                        return itemContainer.GetType();

                    }

                }

            }



            return null;

        }



        // [jelled] Changed GetItemsPanelOrientation to look from the bottom element up instead of top-down (to support groups).

        public static Orientation GetItemsPanelOrientation(this UIElement item)

        {

            ItemsPresenter itemsPresenter = item.GetVisualAncestor<ItemsPresenter>();

            if (itemsPresenter != null)

            {

                DependencyObject itemsPanel = VisualTreeHelper.GetChild(itemsPresenter, 0);

                PropertyInfo orientationProperty = itemsPanel.GetType().GetProperty("Orientation", typeof(Orientation));



                if (orientationProperty != null)

                {

                    return (Orientation)orientationProperty.GetValue(itemsPanel, null);

                }

            }



            // Make a guess!

            return Orientation.Vertical;

        }



        //public static Orientation GetItemsPanelOrientation(this ItemsControl itemsControl)

        //{

        //    ItemsPresenter itemsPresenter = itemsControl.GetVisualDescendent<ItemsPresenter>();

        //    DependencyObject itemsPanel = VisualTreeHelper.GetChild(itemsPresenter, 0);

        //    PropertyInfo orientationProperty = itemsPanel.GetType().GetProperty("Orientation", typeof(Orientation));



        //    if (orientationProperty != null)

        //    {

        //        return (Orientation)orientationProperty.GetValue(itemsPanel, null);

        //    }

        //    else

        //    {

        //        // Make a guess!

        //        return Orientation.Vertical;

        //    }

        //}



        public static void SetSelectedItem(this ItemsControl itemsControl, object item)

        {

            if (itemsControl is MultiSelector)

            {

                ((MultiSelector)itemsControl).SelectedItem = null;

                ((MultiSelector)itemsControl).SelectedItem = item;

            }

            else if (itemsControl is ListBox)

            {

                ((ListBox)itemsControl).SelectedItem = null;

                ((ListBox)itemsControl).SelectedItem = item;

            }

            else if (itemsControl is TreeView)

            {

                // TO DO: Select the TreeViewItem

                //((TreeView)itemsControl)

            }

            else if (itemsControl is Selector)

            {

                ((Selector)itemsControl).SelectedItem = null;

                ((Selector)itemsControl).SelectedItem = item;

            }

        }



        public static IEnumerable GetSelectedItems(this ItemsControl itemsControl)

        {

            if (itemsControl is MultiSelector)

            {

                return ((MultiSelector)itemsControl).SelectedItems;

            }

            else if (itemsControl is ListBox)

            {

                ListBox listBox = (ListBox)itemsControl;



                if (listBox.SelectionMode == SelectionMode.Single)

                {

                    return Enumerable.Repeat(listBox.SelectedItem, 1);

                }

                else

                {

                    return listBox.SelectedItems;

                }

            }

            else if (itemsControl is TreeView)

            {

                return Enumerable.Repeat(((TreeView)itemsControl).SelectedItem, 1);

            }

            else if (itemsControl is Selector)

            {

                return Enumerable.Repeat(((Selector)itemsControl).SelectedItem, 1);

            }

            else

            {

                return Enumerable.Empty<object>();

            }

        }



        public static void SetItemSelected(this ItemsControl itemsControl, object item, bool value)

        {

            if (itemsControl is MultiSelector)

            {

                MultiSelector multiSelector = (MultiSelector)itemsControl;

                if (value)

                {

                    if (multiSelector.CanSelectMultipleItems())

                    {

                        multiSelector.SelectedItems.Add(item);

                    }

                    else

                    {

                        multiSelector.SelectedItem = item;

                    }

                }

                else

                {

                    multiSelector.SelectedItems.Remove(item);

                }

            }

            else if (itemsControl is ListBox)

            {

                ListBox listBox = (ListBox)itemsControl;

                if (value)

                {

                    if (listBox.SelectionMode != SelectionMode.Single)

                    {

                        listBox.SelectedItems.Add(item);

                    }

                    else

                    {

                        listBox.SelectedItem = item;

                    }

                }

                else

                {

                    listBox.SelectedItems.Remove(item);

                }

            }

        }



        static UIElement GetClosest(ItemsControl itemsControl, List<DependencyObject> items,

                                    Point position, Orientation searchDirection)

        {

            UIElement closest = null;

            double closestDistance = double.MaxValue;



            foreach (DependencyObject i in items)

            {

                UIElement uiElement = i as UIElement;



                if (uiElement != null)

                {

                    Point p = uiElement.TransformToAncestor(itemsControl).Transform(new Point(0, 0));

                    double distance = double.MaxValue;



                    switch (searchDirection)

                    {

                        case Orientation.Horizontal:

                            distance = Math.Abs(position.X - p.X);

                            break;

                        case Orientation.Vertical:

                            distance = Math.Abs(position.Y - p.Y);

                            break;

                    }



                    if (distance < closestDistance)

                    {

                        closest = uiElement;

                        closestDistance = distance;

                    }

                }

            }



            return closest;

        }

    }

}