using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using HeuristicLab.PluginInfrastructure;
using System.Windows.Controls;
using AvalonDock;
using System.Windows.Media.Imaging;
using System.Reflection;
using System.Windows.Media;
using HeuristicLab.BackgroundProcessing;
using System.Threading;
using System.Windows.Threading;
using System.ComponentModel;
using System.Windows.Input;
using System.Windows.Controls.Primitives;
using HeuristicLab.Core;
using System.Windows.Forms.Integration;
using HeuristicLab.Common;

namespace HeuristicLab.MainForm.WPF {  

  public abstract class WPFMainFormBase : Window, IMainForm, IControlManager {

    public static readonly Size ToolBarImageSize = new Size(20, 20);
    public abstract Type UserInterfaceItemType { get; }

    public WPFMainFormBase() {
      InitializeComponent();
      InstallExceptionHandlers();
      InitializeBackgroundWorkerMonitoring();
      BuildRootMenu();
      BuildViewsMenu();
      BuildToolBar();
      Messages.Items.Clear();
      DockingManager.PropertyChanged += (sender, args) => {
        if (args.PropertyName == "ActiveDocument")
          OnActiveDocumentChanged();
      };
      MainFormManager.RegisterMainForm(this);
      ControlManager.RegisterManager(this);
    }

    public void ShowControl(object control) {
      object content = null;
      string name = "Control";
      if (control is HeuristicLab.MainForm.IView) {
        content = control;
        name = ((HeuristicLab.MainForm.IView)control).Caption;
      }
      ShowObjectAsView(content, name);
    }

    public IContentView ShowContent(IContent content) {
      throw new NotImplementedException();
    }

    public IContentView ShowContent(IContent content, Type viewType) {
      throw new NotImplementedException();
    }

    #region GUI

    private DockPanel Panel = new DockPanel();
    private Menu Menu = new Menu();
    private ToolBar ToolBar = new ToolBar();
    private StatusBar StatusBar = new StatusBar();
    private StatusBar BackgroundWorkers = new OperationBarPanel();
    private StatusBar Messages = new StatusBar();
    private DocumentPane DocumentPane = new DocumentPane();
    private DockingManager DockingManager = new DockingManager() {
      MinHeight = 50,
    };

    protected void InitializeComponent() {
      StatusBar.Items.Add("OKB Cockpit");
      StatusBar.Items.Add(new Separator());
      StatusBar.Items.Add("Operations:");
      StatusBar.Items.Add(BackgroundWorkers);
      StatusBar.Items.Add(new Separator());
      StatusBar.Items.Add(Messages);
      StatusBar.AddHandler(Button.ClickEvent, new RoutedEventHandler(OperationAborted));
      Menu.SetValue(DockPanel.DockProperty, Dock.Top);
      ToolBar.SetValue(DockPanel.DockProperty, Dock.Top);
      StatusBar.SetValue(DockPanel.DockProperty, Dock.Bottom);
      DockingManager.Content = DocumentPane;
      Panel.Children.Add(Menu);
      Panel.Children.Add(ToolBar);
      Panel.Children.Add(StatusBar);
      Panel.Children.Add(DockingManager);
      Content = Panel;
      Title = "WPF Main Window";
    }

    #endregion

    #region fallback exception handling

    private void InstallExceptionHandlers() {
      AppDomain.CurrentDomain.UnhandledException += CurrentDomain_UnhandledException;
      Dispatcher.UnhandledException += Dispatcher_UnhandledException;
      WorkerMonitor.Default.BackgroundWorkerException += WorkerMonitor_BackgroundWorkerException;
    }

    private void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e) {
      Exception x = e.ExceptionObject as Exception;
      if (x != null)
        ShowException("Unhandled application domain exception", x);
    }

    private void Dispatcher_UnhandledException(object sender, DispatcherUnhandledExceptionEventArgs e) {
      ShowException("Unhandled dispatcher exception", e.Exception);
    }

    private void WorkerMonitor_BackgroundWorkerException(object sender, ThreadExceptionEventArgs e) {
      ShowException(String.Format("'{0}' raised async exception", e.Exception.Message), e.Exception.InnerException);
    }

    protected void ShowException(string message, Exception e) {
      Dispatcher.BeginInvoke(new Action(() => {
        MessageBox.Show(this,
          String.Format("{0}:\n{1}", message, e.ToString()),
          Title, MessageBoxButton.OK, MessageBoxImage.Error);
      }), DispatcherPriority.SystemIdle);
    }

    #endregion

    #region view discovery

    private void BuildViewsMenu() {
      MenuItem viewsMenu = new MenuItem() { Header = "Views" };
      Menu.Items.Add(viewsMenu);
      foreach (Type viewType in ApplicationManager.Manager
          .GetTypes(UserInterfaceItemType)
          .Where(t => t.GetInterface(typeof(IAutoView).FullName) != null)) {
        viewsMenu.Items.Add(CreateViewsMenuEntry(viewType));
      }
    }

    private MenuItem CreateViewsMenuEntry(Type viewType) {
      MenuItem item = new MenuItem() { Header = viewType.Name };
      item.Click += (sender, args) => {
        ShowView((IView)Activator.CreateInstance(viewType, true));
      };
      return item;
    }

    #endregion

    #region menu discovery

    private void BuildRootMenu() {
      foreach (Type menuItemType in
          ApplicationManager.Manager
          .GetTypes(UserInterfaceItemType)
          .Where(t => t.GetInterface(typeof(IMenuItem).FullName) != null)) {
        IMenuItem item = (IMenuItem)Activator.CreateInstance(menuItemType, true);
        AddMenuItem(Menu.Items, item, item.Structure.GetEnumerator());
      }
    }

    private void AddMenuItem(ItemCollection items, IMenuItem newItem, IEnumerator<string> structure) {
      if (structure.MoveNext()) {
        string name = structure.Current;
        MenuItem parent = items.Cast<MenuItem>().SingleOrDefault(i => i.Header as string == name);
        if (parent == null) {
          parent = new MenuItem() { Header = name, Tag = newItem };
          InsertSortedMenuItem(items, parent);
        }
        AddMenuItem(parent.Items, newItem, structure);
      } else {
        MenuItem item = new MenuItem() { Header = newItem.Name, Tag = newItem };
        item.Click += (s, a) => newItem.Execute();
        if (newItem.Image != null)
          item.Icon = newItem.Image;
        WPFMenuItem wpfItem = newItem as WPFMenuItem;
        if (wpfItem != null) {
          wpfItem.MenuItem = item;
          item.IsEnabled = wpfItem.IsEnabled;
          wpfItem.IsEnabledChanged += (s, a) => item.IsEnabled = wpfItem.IsEnabled;
        }
        InsertSortedMenuItem(items, item);
      }
    }

    private static void InsertSortedMenuItem(ItemCollection items, MenuItem menuItem) {
      IMenuItem newItem = menuItem.Tag as IMenuItem;
      if (newItem == null) {
        items.Add(menuItem);
      } else {
        int index = 0;
        while (index < items.Count) {
          MenuItem it = items[index] as MenuItem;
          if (it == null) break;
          IMenuItem item = it.Tag as IMenuItem;
          if (item == null) break;
          if (newItem.Position < item.Position) break;
          index++;
        }
        items.Insert(index, menuItem);
      }
    }

    #endregion

    #region tool bar discovery

    private void BuildToolBar() {
      foreach (Type itemType in
          ApplicationManager.Manager
          .GetTypes(UserInterfaceItemType)
          .Where(t => t.GetInterface(typeof(IToolBarItem).FullName) != null)) {
        IToolBarItem item = (IToolBarItem)Activator.CreateInstance(itemType, true);
        StackPanel visualItem = new StackPanel() { Orientation = Orientation.Vertical };
        Image image =
          ImageConverter.Win32Image2WPFImage(item.Image) ??
          new Image() {
            Source = new BitmapImage(new Uri(
              "pack://application:,,,/" +
              Assembly.GetExecutingAssembly().GetName().Name +
              ";component/Images/Lambda.png"))
          };
        image.Width = ToolBarImageSize.Width;
        image.Height = ToolBarImageSize.Height;
        image.Stretch = Stretch.UniformToFill;
        visualItem.Children.Add(image);
        visualItem.Children.Add(new TextBlock() { Text = item.Name });
        Button b = new Button() { Content = visualItem };
        b.Click += (s, a) => item.Execute();
        WPFToolBarItem wpfItem = item as WPFToolBarItem;
        if (wpfItem != null) {
          b.IsEnabled = wpfItem.IsEnabled;
          if (wpfItem.IsVisible)
            b.Visibility = Visibility.Visible;
          else
            b.Visibility = Visibility.Collapsed;
          wpfItem.IsEnabledChanged += (s, a) => b.IsEnabled = wpfItem.IsEnabled;
          wpfItem.IsVisibleChanged += (s, a) => {
            if (wpfItem.IsVisible)
              b.Visibility = Visibility.Visible;
            else
              b.Visibility = Visibility.Collapsed;
          };
        }
        ToolBar.Items.Add(b);
      }
    }

    #endregion

    #region Background Worker Monitoring

    private void InitializeBackgroundWorkerMonitoring() {
      var BackgroundWorkerView = new DispatchedView<ObservableBackgroundWorker>(
        WorkerMonitor.Default, Dispatcher, DispatcherPriority.SystemIdle);
      BackgroundWorkers.ItemsSource = BackgroundWorkerView;
      BackgroundWorkerView.CollectionChanged += (sender, args) => {
        if (args.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Add) {
          if (Cursor != Cursors.AppStarting)
            Cursor = Cursors.AppStarting;
        } else {
          bool active = BackgroundWorkerView.Count() > 0;
          if (active && Cursor == Cursors.Arrow) {
            Cursor = Cursors.AppStarting;
          } else if (!active && Cursor == Cursors.AppStarting) {
            Cursor = Cursors.Arrow;
          }
        }
      };
    }

    protected void OperationAborted(object sender, RoutedEventArgs args) {
      Button button = args.OriginalSource as Button;
      if (button == null) return;
      ObservableBackgroundWorker worker = button.Tag as ObservableBackgroundWorker;
      if (worker == null) return;
      if (worker.WorkerSupportsCancellation &&
        MessageBox.Show(this,
          String.Format("Do you want to cancel the background execution of '{0}'?", worker.Name), Title,
          MessageBoxButton.YesNo, MessageBoxImage.Question) ==
          MessageBoxResult.Yes)
        worker.CancelAsync();
      args.Handled = true;
    }

    protected override void OnClosing(CancelEventArgs e) {
      base.OnClosing(e);
      if (WorkerMonitor.Default.Count() > 0) {
        var result = MessageBox.Show(
          this,
          "You have tasks running in the background. Do you want to signal and wait for their termination?",
          Title,
          MessageBoxButton.YesNoCancel,
          MessageBoxImage.Warning);
        if (result == MessageBoxResult.Cancel || result == MessageBoxResult.None)
          e.Cancel = true;
        else if (result == MessageBoxResult.Yes)
          WorkerMonitor.Default.CancelAllAsync();
        Thread.Sleep(0);
      }
    }

    protected override void OnClosed(EventArgs e) {
      AppDomain.CurrentDomain.UnhandledException -= CurrentDomain_UnhandledException;
      Dispatcher.UnhandledException -= Dispatcher_UnhandledException;
      WorkerMonitor.Default.BackgroundWorkerException += WorkerMonitor_BackgroundWorkerException;
      base.OnClosed(e);
    }

    #endregion

    #region Status Messages

    class Message : IStatusMessage {

      public string Text { get; set; }
      public Action HideAction { get; set; }

      public override string ToString() {
        return Text;
      }

      public void Hide() {
        HideAction();
      }
    }

    public interface IStatusMessage {
      string Text { get; }
      void Hide();
    }

    public IStatusMessage ShowMessage(string message, TimeSpan duration) {
      Message m = new Message() { Text = message };
      DispatcherTimer timer = new DispatcherTimer() { Interval = duration };
      Action hideAction = () => {
        Messages.Items.Remove(m);
        timer.Stop();
      };
      m.HideAction = hideAction;
      Messages.Items.Add(m);
      if (duration != TimeSpan.Zero) {
        timer.Tick += (sender, args) => {
          hideAction();
        };
        timer.Start();
      }
      return m;
    }

    #endregion

    #region View management

    public event EventHandler<ViewEventArgs> ViewClosed;
    public event EventHandler<ViewShownEventArgs> ViewShown;
    public event EventHandler<ViewEventArgs> ViewHidden;

    protected void OnViewClosed(IView view) {
      EventHandler<ViewEventArgs> handler = ViewClosed;
      if (handler != null)
        handler(this, new ViewEventArgs(view));
    }

    protected void OnViewShown(IView view, bool firstTimeShown) {
      EventHandler<ViewShownEventArgs> handler = ViewShown;
      if (handler != null)
        handler(this, new ViewShownEventArgs(view, firstTimeShown));
    }

    protected void OnViewHidden(IView view) {
      EventHandler<ViewEventArgs> handler = ViewHidden;
      if (handler != null)
        handler(this, new ViewEventArgs(view));
    }

    public IEnumerable<IView> Views {
      get {
        return DockingManager.DockableContents
          .Select(c => c.Content)
          .Where(c => c is IView)
          .Cast<IView>().AsEnumerable();
      }
    }

    public IView ActiveView {
      get {
        return DockingManager.ActiveContent as IView;
      }
    }

    protected void OnActiveDocumentChanged() {
      EventHandler handler = ActiveViewChanged;
      if (handler != null)
        handler(null, EventArgs.Empty);
    }

    public event EventHandler ActiveViewChanged;

    private void ShowObjectAsView(object o, string name) {
      if (o as System.Windows.Forms.Control != null) {
        o = new WindowsFormsHost() { Child = (System.Windows.Forms.Control)o };
      }
      var content = new DockableContent() {
        Content = o,
        Title = name,
        HideOnClose = false,
      };
      DocumentPane.Items.Add(content);
      DocumentPane.SelectedItem = content;
    }

    public DockableContent AddView(IView view) {
      try {
        DockableContent content = new DockableContent() {
          Content = view,
          Title = view.Caption,
          HideOnClose = true, // to enable capturing of state change events
        };
        content.StateChanged += (s, a) => {
          if (a == DockableContentState.Hidden) {
            OnViewClosed(view);
            content.HideOnClose = false;
            // HideOnClose moves content to _hiddenContents private member.
            // To remove it from there, we have to show the content again
            // to move it back into an accessible container and remove
            // it from there.
            Dispatcher.BeginInvoke(new Action(() => {
              DockingManager.Show(content);
              content.ContainerPane.Items.Remove(content);
            }));
          } else {
            OnViewShown(view, false);
          }
        };
        DocumentPane.Items.Add(content);
        DocumentPane.SelectedItem = content;
        OnViewShown(view, true);
        return content;
      } catch (Exception x) {
        MessageBox.Show(this,
          String.Format("Could not add view '{0}':\n{1}", view.Caption, x.ToString()),
          Title,
          MessageBoxButton.OK, MessageBoxImage.Exclamation);
        return null;
      }
    }

    /// <summary>
    /// Show existing view or create new one. Return true if this is the first time shown.
    /// </summary>    
    public bool ShowView(IView view) {
      DockableContent content = GetContent(view);
      if (content == null) {
        content = AddView(view);
        return true;
      } else {
        DockingManager.Show(content);
        content.ContainerPane.SelectedItem = content;
        OnViewShown(view, false);
        return false;
      }
    }

    public void HideView(IView view) {
      DockableContent content = GetContent(view);
      if (content != null)
        DockingManager.Hide(content);
      OnViewHidden(view);
    }

    public void CloseView(IView view) {
      DockableContent content = GetContent(view);
      content.ContainerPane.Items.Remove(content);
      OnViewClosed(view);
    }

    public void CloseAllViews() {
      foreach (var viewContainer in DockingManager.DockableContents.Where(c => c.Content is IView)) {
        viewContainer.ContainerPane.Items.Remove(viewContainer);
        OnViewClosed(viewContainer.Content as IView);
      }
    }

    private DockableContent GetContent(IView view) {
      DockableContent content =
        DockingManager
        .DockableContents
        .SingleOrDefault(c => c.Content as IView == view);
      return content;
    }

    #endregion

    #region IMainForm

    public event EventHandler Changed;

    protected void OnChanged() {
      EventHandler handler = Changed;
      if (handler != null)
        handler(this, EventArgs.Empty);
    }

    #endregion
  }
}