// -----------------------------------------------------------------------
// <copyright file="TreeView.cs" company="Steven Kirk">
// Copyright 2014 MIT Licence. See licence.md for more information.
// </copyright>
// -----------------------------------------------------------------------

namespace Perspex.Controls
{
    using System;
    using System.Collections;
    using System.Collections.Generic;
    using System.Linq;
    using Perspex.Controls.Generators;
    using Perspex.Input;
    using Perspex.VisualTree;

    public class TreeView : ItemsControl
    {
        public static readonly PerspexProperty<object> SelectedItemProperty =
            PerspexProperty.Register<TreeView, object>("SelectedItem", validate: ValidateSelectedItem);

        static TreeView()
        {
            SelectedItemProperty.Changed.Subscribe(x =>
            {
                var control = x.Sender as TreeView;

                if (control != null)
                {
                    control.SelectedItemChanged(x.NewValue);
                }
            });
        }

        public object SelectedItem
        {
            get { return this.GetValue(SelectedItemProperty); }
            set { this.SetValue(SelectedItemProperty, value); }
        }

        protected override IItemContainerGenerator CreateItemContainerGenerator()
        {
            return new TreeItemContainerGenerator<TreeViewItem>(this);
        }

        protected virtual void MoveSelection(FocusNavigationDirection direction)
        {
            // TODO: Up and down movement is a *HACK* and probably pretty slow. Probably needs
            // rewriting at some point.
            ////if (this.SelectedItem != null)
            ////{
            ////    switch (direction)
            ////    {
            ////        case FocusNavigationDirection.Up:
            ////            {
            ////                var list = this.Flatten();
            ////                var index = list.IndexOf(this.SelectedItem);

            ////                if (index > 0)
            ////                {
            ////                    this.SelectedItem = list[index - 1];
            ////                }

            ////                break;
            ////            }

            ////        case FocusNavigationDirection.Down:
            ////            {
            ////                var list = this.Flatten();
            ////                var index = list.IndexOf(this.SelectedItem);

            ////                if (index + 1 < list.Count)
            ////                {
            ////                    this.SelectedItem = list[index + 1];
            ////                }

            ////                break;
            ////            }

            ////        case FocusNavigationDirection.Left:
            ////            {
            ////                var node = (TreeViewItem)this.ItemContainerGenerator.GetContainerForItem(this.SelectedItem);
            ////                node.IsExpanded = false;
            ////                break;
            ////            }

            ////        case FocusNavigationDirection.Right:
            ////            {
            ////                var node = (TreeViewItem)this.ItemContainerGenerator.GetContainerForItem(this.SelectedItem);
            ////                node.IsExpanded = true;
            ////                break;
            ////            }
            ////    }
            ////}
        }

        protected override void OnKeyDown(KeyEventArgs e)
        {
            ////base.OnKeyDown(e);

            ////if (!e.Handled)
            ////{
            ////    switch (e.Key)
            ////    {
            ////        case Key.Up:
            ////            this.MoveSelection(FocusNavigationDirection.Up);
            ////            break;
            ////        case Key.Down:
            ////            this.MoveSelection(FocusNavigationDirection.Down);
            ////            break;
            ////        case Key.Left:
            ////            this.MoveSelection(FocusNavigationDirection.Left);
            ////            break;
            ////        case Key.Right:
            ////            this.MoveSelection(FocusNavigationDirection.Right);
            ////            break;
            ////        default:
            ////            return;
            ////    }

            ////    var selected = this.SelectedItem;

            ////    if (selected != null)
            ////    {
            ////        var container = this.ItemContainerGenerator.GetContainerForItem(selected);

            ////        if (container != null)
            ////        {
            ////            container.BringIntoView();
            ////            FocusManager.Instance.Focus(container, true);
            ////        }
            ////    }

            ////    e.Handled = true;
            ////}
        }

        protected override void OnPointerPressed(PointerPressEventArgs e)
        {
            ////IVisual source = (IVisual)e.Source;
            ////var selectable = source.GetVisualAncestors()
            ////    .OfType<ISelectable>()
            ////    .OfType<Control>()
            ////    .FirstOrDefault();

            ////if (selectable != null)
            ////{
            ////    var item = this.ItemContainerGenerator.GetItemForContainer(selectable);

            ////    if (item != null)
            ////    {
            ////        this.SelectedItem = item;
            ////        selectable.BringIntoView();
            ////        FocusManager.Instance.Focus(selectable);
            ////    }
            ////}

            ////e.Handled = true;
        }

        private static object ValidateSelectedItem(PerspexObject o, object value)
        {
            //var control = o as SelectingItemsControl;

            //if (control != null)
            //{
            //    if (value != null && (control.Items == null || control.Items.IndexOf(value) == -1))
            //    {
            //        return null;
            //    }
            //}

            return value;
        }

        private List<object> Flatten()
        {
            var result = new List<object>();
            this.Flatten(this.Items, result);
            return result;
        }

        private void Flatten(IEnumerable items, List<object> result)
        {
            ////if (items != null)
            ////{
            ////    foreach (object item in items)
            ////    {
            ////        var container = (TreeViewItem)this.ItemContainerGenerator.GetContainerForItem(item);
            ////        result.Add(item);

            ////        if (container.IsExpanded)
            ////        {
            ////            this.Flatten(container.Items, result);
            ////        }
            ////    }
            ////}
        }

        private void SelectedItemChanged(object selected)
        {
            ////var containers = this.ItemContainerGenerator.GetAll()
            ////    .Select(x => x.Item2)
            ////    .OfType<ISelectable>();
            ////var selectedContainer = (selected != null) ?
            ////    this.ItemContainerGenerator.GetContainerForItem(selected) :
            ////    null;

            ////if (this.Presenter != null && this.Presenter.Panel != null)
            ////{
            ////    KeyboardNavigation.SetTabOnceActiveElement(this.Presenter.Panel, selectedContainer);
            ////}

            ////foreach (var item in containers)
            ////{
            ////    item.IsSelected = item == selectedContainer;
            ////}
        }
    }
}