#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2016 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Windows.Forms;
using HeuristicLab.Common;

namespace HeuristicLab.MainForm.WindowsForms {
  [Content(typeof(IContent))]
  public partial class ViewHost : AsynchronousContentView {
    public ViewHost() {
      InitializeComponent();
      startDragAndDrop = false;
      viewContextMenuStrip.IgnoredViewTypes = new List<Type>() { typeof(ViewHost) };

      viewType = null;
      activeView = null;
      Content = null;
      messageLabel.Visible = false;
      viewsLabel.Visible = false;
      viewsLabelVisible = true;
    }

    private bool viewsLabelVisible;
    public bool ViewsLabelVisible {
      get { return viewsLabelVisible; }
      set {
        if (viewsLabelVisible != value) {
          viewsLabelVisible = value;
          viewsLabel.Visible = value;
          View view = activeView as View;
          if (view != null) view.Dock = viewsLabelVisible ? DockStyle.None : DockStyle.Fill;
        }
      }
    }

    private IContentView cachedView;
    private IContentView activeView;
    public IContentView ActiveView {
      get { return activeView; }
      private set {
        if (activeView != value) {
          if (activeView != null) {
            cachedView = activeView;
            DeregisterActiveViewEvents();
            View cached = cachedView as View;
            if (cached != null) {
              cached.OnHidden(EventArgs.Empty);
              cached.Visible = false;
            }
          }

          activeView = value;

          if (activeView != null) {
            #region dispose cachedView
            if (activeView != cachedView) {
              if (cachedView != null) cachedView.Content = null;  //needed to deregister events
              View cached = cachedView as View;
              if (cached != null) {
                Controls.Remove(cached);
                cached.Dispose();
              }
              cachedView = null;
            }
            #endregion

            this.Caption = activeView.Caption;
            viewType = activeView.GetType();
            RegisterActiveViewEvents();
            View view = activeView as View;
            if (view != null) {
              view.Visible = true;
              ConfigureViewLayout(view);
              if (!Controls.Contains((view))) Controls.Add(view);
              view.OnShown(new ViewShownEventArgs(view, false));
            }
          } else viewType = null;
          configurationLabel.Visible = activeView is IConfigureableView;
          configurationLabel.Enabled = activeView != null && !activeView.Locked;

          helpLabel.Visible = activeView != null && ViewAttribute.HasHelpResourcePath(activeView.GetType());
          helpLabel.Top = CalculateHelpLabelPosY();
        }
      }
    }

    protected virtual void ConfigureViewLayout(View view) {
      if (ViewsLabelVisible) {
        view.Anchor = AnchorStyles.Bottom | AnchorStyles.Left | AnchorStyles.Top | AnchorStyles.Right;
        view.Size = new Size(Width - viewsLabel.Width - viewsLabel.Margin.Left - viewsLabel.Margin.Right, Height);
      } else view.Dock = DockStyle.Fill;
    }

    private Type viewType;
    public Type ViewType {
      get { return viewType; }
      set {
        if (viewType != value) {
          if (value == typeof(ViewHost))
            throw new ArgumentException("Directly nested ViewHosts are not allowed.");
          if (value != null && Content != null && !ViewCanShowContent(value, Content))
            throw new ArgumentException(string.Format("View \"{0}\" cannot display content \"{1}\".", value, Content.GetType()));

          viewType = value;
          OnViewTypeChanged();
        }
      }
    }

    protected override void SetEnabledStateOfControls() {
      Enabled = Content != null;
    }

    protected override void OnContentChanged() {
      viewContextMenuStrip.Item = Content;
      //change ViewType if view of ViewType can not show content or is null
      if (Content != null) {
        if (!ViewCanShowContent(viewType, Content)) {
          Type defaultViewType = MainFormManager.GetDefaultViewType(Content.GetType());
          if (cachedView != null && cachedView.GetType() == defaultViewType)
            ActiveView = cachedView;
          else if (defaultViewType != null)
            ViewType = defaultViewType;
          else if (viewContextMenuStrip.Items.Count > 0)  // create first available view if no default view is available
            ViewType = (Type)viewContextMenuStrip.Items[0].Tag;
          else {
            ViewType = null;
            ActiveView = null;
          }
        }
        if (ActiveView != null) ActiveView.Content = Content;
      } else ActiveView = null;
      UpdateLabels();
      UpdateActiveMenuItem();
    }

    private void UpdateLabels() {
      if (Content != null && viewContextMenuStrip.Items.Count > 0) {
        messageLabel.Visible = false;
        viewsLabel.Visible = viewsLabelVisible;
      } else if (Content != null) {
        messageLabel.Visible = true;
        viewsLabel.Visible = false;
      } else {
        messageLabel.Visible = false;
        viewsLabel.Visible = false;
      }
    }

    private void OnViewTypeChanged() {
      if (viewType != null) {
        if (!ViewCanShowContent(viewType, Content))
          throw new InvalidOperationException(string.Format("View \"{0}\" cannot display content \"{1}\".",
                                                            viewType, Content.GetType()));
        IContentView view = MainFormManager.CreateView(viewType);
        view.Locked = Locked;
        view.ReadOnly = ReadOnly;
        ActiveView = view; //necessary to allow the views to change the status of the viewhost
        view.Content = Content;

        UpdateActiveMenuItem();
      }
    }

    private void RegisterActiveViewEvents() {
      activeView.CaptionChanged += new EventHandler(activeView_CaptionChanged);
      activeView.LockedChanged += new EventHandler(activeView_LockedChanged);
      activeView.Changed += new EventHandler(activeView_Changed);
    }
    private void DeregisterActiveViewEvents() {
      activeView.CaptionChanged -= new EventHandler(activeView_CaptionChanged);
      activeView.LockedChanged -= new EventHandler(activeView_LockedChanged);
      activeView.Changed -= new EventHandler(activeView_Changed);
    }
    private void activeView_CaptionChanged(object sender, EventArgs e) {
      Caption = activeView.Caption;
    }
    private void activeView_LockedChanged(object sender, EventArgs e) {
      Locked = activeView.Locked;
      configurationLabel.Enabled = !activeView.Locked;
    }
    private void activeView_Changed(object sender, EventArgs e) {
      OnChanged();
    }

    protected override void OnSizeChanged(EventArgs e) {
      //mkommend: solution to resizing issues. taken from http://support.microsoft.com/kb/953934
      //not implemented with a panel to reduce the number of nested controls
      //also cf. http://connect.microsoft.com/VisualStudio/feedback/details/98368/csc-incorrectly-allows-comparison-between-intptr-and-null
      if (Handle != IntPtr.Zero)
        this.BeginInvoke((Action<EventArgs>)OnSizeChangedHelper, e);
    }
    private void OnSizeChangedHelper(EventArgs e) {
      base.OnSizeChanged(e);
      viewsLabel.Location = new Point(Width - viewsLabel.Margin.Right - viewsLabel.Width, viewsLabel.Margin.Top);
      configurationLabel.Location = new Point(Width - configurationLabel.Margin.Right - configurationLabel.Width, viewsLabel.Bottom + viewsLabel.Margin.Bottom + configurationLabel.Margin.Top);
      helpLabel.Location = new Point(Width - helpLabel.Margin.Right - helpLabel.Width, CalculateHelpLabelPosY());
    }

    private int CalculateHelpLabelPosY() {
      if (activeView != null && ViewAttribute.HasHelpResourcePath(activeView.GetType()) && !configurationLabel.Visible) {
        return configurationLabel.Top;
      }
      return configurationLabel.Bottom + configurationLabel.Margin.Bottom + helpLabel.Margin.Top;
    }

    #region forwarding of view events
    internal protected override void OnShown(ViewShownEventArgs e) {
      base.OnShown(e);
      View view = ActiveView as View;
      if (view != null)
        view.OnShown(e);
    }
    internal protected override void OnHidden(EventArgs e) {
      base.OnHidden(e);
      View view = ActiveView as View;
      if (view != null)
        view.OnHidden(e);
    }
    internal protected override void OnClosing(FormClosingEventArgs e) {
      base.OnClosing(e);
      View view = ActiveView as View;
      if (view != null)
        view.OnClosing(e);
    }
    internal protected override void OnClosed(FormClosedEventArgs e) {
      base.OnClosed(e);
      View view = ActiveView as View;
      if (view != null)
        view.OnClosed(e);
    }
    #endregion

    #region GUI actions
    private void UpdateActiveMenuItem() {
      foreach (KeyValuePair<Type, ToolStripMenuItem> item in viewContextMenuStrip.MenuItems) {
        if (item.Key == viewType) {
          item.Value.Checked = true;
          item.Value.Enabled = false;
        } else {
          item.Value.Checked = false;
          item.Value.Enabled = true;
        }
      }
    }

    private bool ViewCanShowContent(Type viewType, object content) {
      if (content == null) // every view can display null
        return true;
      if (viewType == null)
        return false;
      return ContentAttribute.CanViewType(viewType, Content.GetType()) && viewContextMenuStrip.MenuItems.Any(item => item.Key == viewType);
    }

    private void viewsLabel_DoubleClick(object sender, EventArgs e) {
      IContentView view = MainFormManager.MainForm.ShowContent(this.Content, this.ViewType);
      if (view != null) {
        view.ReadOnly = this.ReadOnly;
        view.Locked = this.Locked;
      }
    }
    private void viewContextMenuStrip_ItemClicked(object sender, ToolStripItemClickedEventArgs e) {
      Type viewType = (Type)e.ClickedItem.Tag;
      ViewType = viewType;
    }

    private bool startDragAndDrop;
    private void viewsLabel_MouseDown(object sender, MouseEventArgs e) {
      if (e.Button == System.Windows.Forms.MouseButtons.Right) {
        Screen screen = Screen.FromControl(viewsLabel);
        int rightBorder = viewsLabel.PointToScreen(viewsLabel.Location).X + viewContextMenuStrip.Width; //
        rightBorder = rightBorder - screen.Bounds.X; //pixel position on active screen

        if (rightBorder < screen.Bounds.Width)
          viewContextMenuStrip.Show(viewsLabel, viewsLabel.Margin.Left, viewsLabel.Margin.Top);
        else
          viewContextMenuStrip.Show(screen.Bounds.X + screen.Bounds.Width - viewContextMenuStrip.Width, viewsLabel.PointToScreen(viewsLabel.Location).Y - viewsLabel.Margin.Top);
      } else if (!Locked) {
        startDragAndDrop = true;
        viewsLabel.Capture = false;
        viewsLabel.Focus();
      }
    }
    private void viewsLabel_MouseLeave(object sender, EventArgs e) {
      if ((Control.MouseButtons & MouseButtons.Left) == MouseButtons.Left && startDragAndDrop) {
        DataObject data = new DataObject();
        data.SetData(HeuristicLab.Common.Constants.DragDropDataFormat, Content);
        DoDragDrop(data, DragDropEffects.Copy | DragDropEffects.Link);
      } else
        startDragAndDrop = false;
    }

    private void configurationLabel_DoubleClick(object sender, MouseEventArgs e) {
      ((IConfigureableView)ActiveView).ShowConfiguration();
    }

    private void helpLabel_DoubleClick(object sender, EventArgs e) {
      using (InfoBox dialog = new InfoBox("Help for " + ViewAttribute.GetViewName(ActiveView.GetType()), ViewAttribute.GetHelpResourcePath(ActiveView.GetType()), ActiveView)) {
        dialog.ShowDialog(this);
      }
    }
    #endregion
  }
}