//===================================================================================

// Microsoft patterns & practices

// Composite Application Guidance for Windows Presentation Foundation and Silverlight

//===================================================================================

// Copyright (c) Microsoft Corporation.  All rights reserved.

// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY

// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT

// LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

// FITNESS FOR A PARTICULAR PURPOSE.

//===================================================================================

// The example companies, organizations, products, domain names,

// e-mail addresses, logos, people, places, and events depicted

// herein are fictitious.  No association with any real company,

// organization, product, domain name, email address, logo, person,

// places, or events is intended or should be inferred.

//===================================================================================

using System;

using System.Collections.Generic;

using System.Collections.Specialized;

using System.Windows;

using System.Windows.Controls;

using Microsoft.Practices.Prism.Properties;



namespace Microsoft.Practices.Prism.Regions.Behaviors

{

    /// <summary>

    /// Behavior that generates <see cref="TabItem"/> containers for the added items

    /// and also keeps the <see cref="TabControl.SelectedItem"/> and the <see cref="IRegion.ActiveViews"/> in sync.

    /// </summary>

    public class TabControlRegionSyncBehavior : RegionBehavior, IHostAwareRegionBehavior

    {

        ///<summary>

        /// The behavior key for this region sync behavior.

        ///</summary>

        public const string BehaviorKey = "TabControlRegionSyncBehavior";



        private static readonly DependencyProperty IsGeneratedProperty =

            DependencyProperty.RegisterAttached("IsGenerated", typeof(bool), typeof(TabControlRegionSyncBehavior), null);



        private TabControl hostControl;



        /// <summary>

        /// Gets or sets the <see cref="DependencyObject"/> that the <see cref="IRegion"/> is attached to.

        /// </summary>

        /// <value>A <see cref="DependencyObject"/> that the <see cref="IRegion"/> is attached to.

        /// This is usually a <see cref="FrameworkElement"/> that is part of the tree.</value>

        public DependencyObject HostControl

        {

            get

            {

                return this.hostControl;

            }



            set

            {

                TabControl newValue = value as TabControl;

                if (newValue == null)

                {

                    throw new InvalidOperationException(Resources.HostControlMustBeATabControl);

                }



                if (IsAttached)

                {

                    throw new InvalidOperationException(Resources.HostControlCannotBeSetAfterAttach);

                }



                this.hostControl = newValue;

            }

        }



        /// <summary>

        /// Override this method to perform the logic after the behavior has been attached.

        /// </summary>

        protected override void OnAttach()

        {

            if (this.hostControl == null)

            {

                throw new InvalidOperationException(Resources.HostControlCannotBeNull);

            }



            this.SynchronizeItems();



            this.hostControl.SelectionChanged += this.OnSelectionChanged;

            this.Region.ActiveViews.CollectionChanged += this.OnActiveViewsChanged;

            this.Region.Views.CollectionChanged += this.OnViewsChanged;

        }



        /// <summary>

        /// Gets the item contained in the <see cref="TabItem"/>.

        /// </summary>

        /// <param name="tabItem">The container item.</param>

        /// <returns>The item contained in the <paramref name="tabItem"/> if it was generated automatically by the behavior; otherwise <paramref name="tabItem"/>.</returns>

        protected virtual object GetContainedItem(TabItem tabItem)

        {

            if (tabItem == null) throw new ArgumentNullException("tabItem");

            if ((bool)tabItem.GetValue(IsGeneratedProperty))

            {

                return tabItem.Content;

            }



            return tabItem;

        }



        /// <summary>

        /// Override to change how TabItem's are prepared for items.

        /// </summary>

        /// <param name="item">The item to wrap in a TabItem</param>

        /// <param name="parent">The parent <see cref="DependencyObject"/></param>

        /// <returns>A tab item that wraps the supplied <paramref name="item"/></returns>

        protected virtual TabItem PrepareContainerForItem(object item, DependencyObject parent)

        {

            TabItem container = item as TabItem;

            if (container == null)

            {

                object dataContext = GetDataContext(item);

                container = new TabItem();

                container.Content = item;

                container.Style = TabControlRegionAdapter.GetItemContainerStyle(parent);

                container.DataContext = dataContext; // To run with SL 2

                container.Header = dataContext; // To run with SL 3                  

                container.SetValue(IsGeneratedProperty, true);

            }



            return container;

        }



        /// <summary>

        /// Undoes the effects of the <see cref="PrepareContainerForItem"/> method.

        /// </summary>

        /// <param name="tabItem">The container element for the item.</param>

        protected virtual void ClearContainerForItem(TabItem tabItem)

        {

            if (tabItem == null) throw new ArgumentNullException("tabItem");

            if ((bool)tabItem.GetValue(IsGeneratedProperty))

            {

                tabItem.Content = null;

            }

        }



        /// <summary>

        /// Creates or identifies the element that is used to display the given item.

        /// </summary>

        /// <param name="item">The item to get the container for.</param>

        /// <param name="itemCollection">The parent's <see cref="ItemCollection"/>.</param>

        /// <returns>The element that is used to display the given item.</returns>

        protected virtual TabItem GetContainerForItem(object item, ItemCollection itemCollection)

        {

            if (itemCollection == null) throw new ArgumentNullException("itemCollection");

            TabItem container = item as TabItem;

            if (container != null && ((bool)container.GetValue(IsGeneratedProperty)) == false)

            {

                return container;

            }



            foreach (TabItem tabItem in itemCollection)

            {

                if ((bool)tabItem.GetValue(IsGeneratedProperty))

                {

                    if (tabItem.Content == item)

                    {

                        return tabItem;

                    }

                }

            }





            return null;

        }



        /// <summary>

        /// Return the appropriate data context.  If the item is a FrameworkElement it cannot be a data context in Silverlight, so we use its data context.

        /// Otherwise, we just us the item as the data context.

        /// </summary>

        private static object GetDataContext(object item)

        {

            FrameworkElement frameworkElement = item as FrameworkElement;

            return frameworkElement == null ? item : frameworkElement.DataContext;

        }



        private void SynchronizeItems()

        {

            List<object> existingItems = new List<object>();

            if (this.hostControl.Items.Count > 0)

            {

                // Control must be empty before "Binding" to a region

                foreach (object childItem in this.hostControl.Items)

                {

                    existingItems.Add(childItem);

                }

            }



            foreach (object view in this.Region.Views)

            {

                TabItem tabItem = this.PrepareContainerForItem(view, this.hostControl);

                this.hostControl.Items.Add(tabItem);

            }



            foreach (object existingItem in existingItems)

            {

                this.Region.Add(existingItem);

            }

        }



        private void OnSelectionChanged(object sender, SelectionChangedEventArgs e)

        {

            // e.OriginalSource == null, that's why we use sender.

            if (this.hostControl == sender)

            {

                foreach (TabItem tabItem in e.RemovedItems)

                {

                    object item = this.GetContainedItem(tabItem);



                    // check if the view is in both Views and ActiveViews collections (there may be out of sync)

                    if (this.Region.Views.Contains(item) && this.Region.ActiveViews.Contains(item))

                    {

                        this.Region.Deactivate(item);

                    }

                }



                foreach (TabItem tabItem in e.AddedItems)

                {

                    object item = this.GetContainedItem(tabItem);

                    if (!this.Region.ActiveViews.Contains(item))

                    {

                        this.Region.Activate(item);

                    }

                }

            }

        }



        private void OnActiveViewsChanged(object sender, NotifyCollectionChangedEventArgs e)

        {

            if (e.Action == NotifyCollectionChangedAction.Add)

            {

                this.hostControl.SelectedItem = this.GetContainerForItem(e.NewItems[0], this.hostControl.Items);

            }

            else if (e.Action == NotifyCollectionChangedAction.Remove

                && this.hostControl.SelectedItem != null

                && e.OldItems.Contains(this.GetContainedItem((TabItem)this.hostControl.SelectedItem)))

            {

                this.hostControl.SelectedItem = null;

            }

        }



        private void OnViewsChanged(object sender, NotifyCollectionChangedEventArgs e)

        {

            if (e.Action == NotifyCollectionChangedAction.Add)

            {

                int startingIndex = e.NewStartingIndex;

                foreach (object newItem in e.NewItems)

                {

                    TabItem tabItem = this.PrepareContainerForItem(newItem, this.hostControl);

                    this.hostControl.Items.Insert(startingIndex, tabItem);

                }

            }

            else if (e.Action == NotifyCollectionChangedAction.Remove)

            {

                foreach (object oldItem in e.OldItems)

                {

                    TabItem tabItem = this.GetContainerForItem(oldItem, this.hostControl.Items);

                    this.hostControl.Items.Remove(tabItem);

                    this.ClearContainerForItem(tabItem);

                }

            }

        }

    }

}