#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.Linq;
using System.Reflection;
using System.Windows.Forms;
using HeuristicLab.Collections;
using HeuristicLab.Core;
using HeuristicLab.Core.Views;
using HeuristicLab.MainForm;
using HeuristicLab.PluginInfrastructure;

namespace HeuristicLab.ItemTreeViews.Views {
  [View("ItemCollection Tree View")]
  [Content(typeof(ItemCollection<>), false)]
  [Content(typeof(IItemCollection<>), false)]
  [Content(typeof(ReadOnlyItemCollection<>), false)]
  public partial class ItemCollectionTreeView<T> : ItemView where T : class, IItem {

    #region properties

    protected Dictionary<T, TreeNode> itemTreeViewItemMapping;
    protected Dictionary<T, T> treeViewChildrenMapping;
    protected TypeSelectorDialog typeSelectorDialog;
    protected bool validDragOperation;

    public new IItemCollection<T> Content
    {
      get { return (IItemCollection<T>)base.Content; }
      set
      {
        base.Content = value;
        OnContentChanged();
      }
    }

    public ObservableCollection<T> ItemCollection { get { return Content as ObservableCollection<T>; } }

    public bool ShowDetails
    {
      get { return showDetailsCheckBox.Checked; }
      set { showDetailsCheckBox.Checked = value; }
    }
    public TreeView ItemsTreeView { get { return itemsTreeView; } }
    #endregion

    public ItemCollectionTreeView() {
      InitializeComponent();
      itemTreeViewItemMapping = new Dictionary<T, TreeNode>();
      treeViewChildrenMapping = new Dictionary<T, T>();
    }
    protected override void Dispose(bool disposing) {
      if (disposing) {
        if (typeSelectorDialog != null) typeSelectorDialog.Dispose();
        if (components != null) components.Dispose();
      }
      base.Dispose(disposing);
    }

    #region eventregistration
    protected override void DeregisterContentEvents() {
      Content.ItemsAdded -= Content_ItemsAdded;
      Content.ItemsRemoved -= Content_ItemsRemoved;
      Content.CollectionReset -= Content_CollectionReset;
      base.DeregisterContentEvents();
    }
    protected override void RegisterContentEvents() {
      DeregisterContentEvents(); //prevent multiattaching
      base.RegisterContentEvents();
      Content.ItemsAdded += Content_ItemsAdded;
      Content.ItemsRemoved += Content_ItemsRemoved;
      Content.CollectionReset += Content_CollectionReset;
    }

    protected virtual void DeregisterItemEvents(T item) {
      item.ItemImageChanged -= Item_ItemImageChanged;
      item.ToStringChanged -= Item_ToStringChanged;
    }
    protected virtual void RegisterItemEvents(T item) {
      DeregisterItemEvents(item); //prevent multiattaching
      item.ItemImageChanged += Item_ItemImageChanged;
      item.ToStringChanged += Item_ToStringChanged;
    }

    protected virtual void DeregisterViewEvents() {
      ItemsTreeView.AfterSelect -= itemsTreeView_SelectedIndexChanged;
      ItemsTreeView.DoubleClick -= itemsTreeView_DoubleClick;
      ItemsTreeView.KeyDown -= itemsTreeView_KeyDown;
    }
    protected virtual void RegisterViewEvents() {
      DeregisterViewEvents(); //prevent multiattaching
      ItemsTreeView.AfterSelect += itemsTreeView_SelectedIndexChanged;
      ItemsTreeView.DoubleClick += itemsTreeView_DoubleClick;
      ItemsTreeView.KeyDown += itemsTreeView_KeyDown;
    }

    protected override void OnContentChanged() {
      ItemsTreeView.BeginUpdate();
      base.OnContentChanged();
      ItemsTreeView.Nodes.Clear();
      itemTreeViewItemMapping.Clear();
      RebuildTreeImageList();
      viewHost.Content = null;
      if (Content == null) { ItemsTreeView.EndUpdate(); return; }
      RegisterViewEvents();
      Caption += " (" + Content.GetType().Name + ")";
      foreach (T item in Content)
        AddTreeNodeRecursive(item, null);
      SortItemsTreeView();
      ItemsTreeView.EndUpdate();
    }
    #endregion

    protected override void SetEnabledStateOfControls() {
      base.SetEnabledStateOfControls();
      if (Content == null) {
        addButton.Enabled = false;
        sortAscendingButton.Enabled = false;
        sortDescendingButton.Enabled = false;
        removeButton.Enabled = false;
        ItemsTreeView.Enabled = false;
        detailsGroupBox.Enabled = false;
      } else {
        addButton.Enabled = !Content.IsReadOnly && !ReadOnly;
        sortAscendingButton.Enabled = false;
        sortDescendingButton.Enabled = false;
        removeButton.Enabled = !Content.IsReadOnly && !ReadOnly && ItemsTreeView.Nodes.Count > 0;
        ItemsTreeView.Enabled = true;
        detailsGroupBox.Enabled = true;
      }
    }
    protected virtual T CreateItem() {
      if (typeSelectorDialog == null) {
        typeSelectorDialog = new TypeSelectorDialog();
        typeSelectorDialog.Caption = "Select Item";
        typeSelectorDialog.TypeSelector.Caption = "Available Items";
        typeSelectorDialog.TypeSelector.Configure(typeof(T), false, true);
      }
      if (typeSelectorDialog.ShowDialog(this) == DialogResult.OK) {
        try {
          return (T)typeSelectorDialog.TypeSelector.CreateInstanceOfSelectedType();
        }
        catch (Exception ex) {
          ErrorHandling.ShowErrorDialog(this, ex);
        }
      }
      return null;
    }
    protected virtual TreeNode CreateTreeViewNode(T item) {
      var treeViewNode = new TreeNode("noName");
      treeViewNode.NodeFont = DefaultFont;
      if (item == null) {
        treeViewNode.Text = "null";
        ItemsTreeView.ImageList.Images.Add(HeuristicLab.Common.Resources.VSImageLibrary.Nothing);
        treeViewNode.ImageIndex = ItemsTreeView.ImageList.Images.Count - 1;
        treeViewNode.SelectedImageIndex = treeViewNode.ImageIndex;
      } else {
        treeViewNode.Text = item.ToString();
        treeViewNode.ToolTipText = item.ItemName + ": " + item.ItemDescription;
        ItemsTreeView.ImageList.Images.Add(item.ItemImage);
        treeViewNode.ImageIndex = ItemsTreeView.ImageList.Images.Count - 1;
        treeViewNode.SelectedImageIndex = treeViewNode.ImageIndex;
        treeViewNode.Tag = item;
      }
      return treeViewNode;
    }

    #region adding
    protected virtual void AddTreeNode(T item) {
      if (item == null || itemTreeViewItemMapping.ContainsKey(item) || !treeViewChildrenMapping.ContainsKey(item))
        return;
      RegisterItemEvents(item);
      var node = CreateTreeViewNode(item);
      itemTreeViewItemMapping[item] = node;
      var p = GetParent(item);
      (p == null ? ItemsTreeView.Nodes : itemTreeViewItemMapping[p].Nodes).Add(node);


    }
    protected void AddTreeNodeRecursive(T item, TreeNode parent) {
      if (item == null) return;
      Queue<T> queue = new Queue<T>();
      queue.Enqueue(item);
      if (!treeViewChildrenMapping.ContainsKey(item))
        treeViewChildrenMapping.Add(item, parent != null ? parent.Tag as T : null); //Set explicitly to null in some cases
      while (queue.Count > 0 && (item = queue.Dequeue()) != null) {
        AddTreeNode(item);
        foreach (var child in ExpandTreeViewItem(item)) { //Expand queue
          if (!treeViewChildrenMapping.ContainsKey(child))
            treeViewChildrenMapping.Add(child, item);
          queue.Enqueue(child);
        }
      }
    }
    protected void UpdateTreeNodeRecursive(T item, TreeNode parent) {
      if (item == null) return;
      Queue<T> queue = new Queue<T>();
      queue.Enqueue(item);
      while (queue.Count > 0 && (item = queue.Dequeue()) != null) {
        AddTreeNode(item);
        var newChildren = ExpandTreeViewItem(item);
        var deadChildren =
          itemTreeViewItemMapping[item].Nodes.Cast<TreeNode>()
            .Select(n => n.Tag as T)
            .Where(t => !newChildren.Contains(t)).Select(t => itemTreeViewItemMapping[t])
            .ToList();

        foreach (var child in newChildren) { //Expand queue
          if (!treeViewChildrenMapping.ContainsKey(child))
            treeViewChildrenMapping.Add(child, item);
          queue.Enqueue(child);
        }

        foreach (var child in deadChildren) {
          RemoveTreeViewItem(child);
        }
      }
    }

    /// <summary>
    /// This function defines which subnodes are created. 
    /// Override this to change which items are used in the creation of new nodes
    /// </summary>
    /// <param name="parent"></param>
    /// <returns></returns>
    protected virtual List<T> ExpandTreeViewItem(object parent) {
      //unpack enumerables
      var p = parent as IEnumerable<T>;
      if (p != null) return p.ToList();
      //exclude LookupParameters from Value unpacking
      if (parent is ILookupParameter) return new List<T>();
      //unpack "value"/"Value"/"ActualValue" relationship if possible
      object prop = GetValue(parent);
      //return nothing if failed
      return (prop != null) ? ExpandTreeViewItem(prop) : new List<T>();
    }
    #endregion

    #region removal 
    private void RemoveTreeViewItem2(TreeNode treeViewItem) {
      if (treeViewItem == null) return;
      T item = treeViewItem.Tag as T;
      if (item != null) {
        treeViewChildrenMapping.Remove(item);
        itemTreeViewItemMapping.Remove(item);
        DeregisterItemEvents(item);
      }
      var children = GetChildren(item);
      foreach (var node in children)
        if (node != null && itemTreeViewItemMapping.ContainsKey(node))
          RemoveTreeViewItem(itemTreeViewItemMapping[node]);
      treeViewItem.Remove();
    }

    protected void RemoveTreeViewItem(TreeNode treeViewNode) {
      var queue = new Queue<TreeNode>(new[] { treeViewNode });
      treeViewNode.Remove();
      while (queue.Count > 0) {
        treeViewNode = queue.Dequeue();
        T item = treeViewNode.Tag as T;
        if (item != null) {
          treeViewChildrenMapping.Remove(item);
          itemTreeViewItemMapping.Remove(item);
          DeregisterItemEvents(item);
        }
        var children = GetChildren(item);
        foreach (var node in children)
          if (node != null && itemTreeViewItemMapping.ContainsKey(node)) queue.Enqueue(itemTreeViewItemMapping[node]);
      }
    }
    #endregion

    protected virtual void UpdateTreeViewItemImage(TreeNode treeViewNode) {
      if (treeViewNode == null) throw new ArgumentNullException();
      var item = treeViewNode.Tag as T;
      var i = treeViewNode.ImageIndex;
      ItemsTreeView.ImageList.Images[i] = item == null ? Common.Resources.VSImageLibrary.Nothing : item.ItemImage;
      treeViewNode.ImageIndex = i;
      treeViewNode.SelectedImageIndex = treeViewNode.ImageIndex;
    }
    protected virtual void UpdateTreeViewItemText(TreeNode treeViewNode) {
      if (treeViewNode == null) throw new ArgumentNullException();
      var item = treeViewNode.Tag as T;
      treeViewNode.Text = item == null ? "null" : item.ToString();
      treeViewNode.ToolTipText = item == null ? string.Empty : item.ItemName + ": " + item.ItemDescription;
    }
    protected virtual TreeNode GetTreeNodeForItem(T item) {
      if (item == null)
        return GetAllNodes(ItemsTreeView).First(x => x.Tag == null);
      TreeNode viewItem;
      itemTreeViewItemMapping.TryGetValue(item, out viewItem);
      return viewItem;
    }

    #region View Events
    protected virtual void itemsTreeView_SelectedIndexChanged(object sender, EventArgs e) {
      removeButton.Enabled = (Content != null) && !Content.IsReadOnly && !ReadOnly && ItemsTreeView.SelectedNode != null;
      if (!showDetailsCheckBox.Checked) return;
      var item = ItemsTreeView.SelectedNode != null ? ItemsTreeView.SelectedNode.Tag as T : null;
      detailsGroupBox.Enabled = true;
      viewHost.Content = item;
    }
    protected virtual void itemsTreeView_KeyDown(object sender, KeyEventArgs e) {
      if (e.KeyCode == Keys.Delete) {
        if ((ItemsTreeView.SelectedNode != null) && !Content.IsReadOnly && !ReadOnly) {
          var selected = GetAllNodes(ItemsTreeView.SelectedNode);
          if (ItemCollection != null) ItemCollection.RemoveRange(selected.Select(i => (T)i.Tag));
          else {
            ItemsTreeView.BeginUpdate();
            foreach (var item in selected) Content.Remove((T)item.Tag);
            ItemsTreeView.EndUpdate();
          }
        }
      }
    }
    protected virtual void itemsTreeView_DoubleClick(object sender, EventArgs e) {
      T item = ItemsTreeView.SelectedNode != null ? ItemsTreeView.SelectedNode.Tag as T : null;
      if (item == null) return;
      IContentView view = MainFormManager.MainForm.ShowContent(item);
      if (view == null) return;
      view.ReadOnly = ReadOnly;
      view.Locked = Locked;
    }
    #endregion

    #region Button Events
    protected virtual void addButton_Click(object sender, EventArgs e) {
      T item = CreateItem();
      if (item != null) Content.Add(item);
    }
    protected virtual void sortAscendingButton_Click(object sender, EventArgs e) {
      SortItemsTreeView();
    }
    protected virtual void sortDescendingButton_Click(object sender, EventArgs e) { //DO nothing for Treeview (no custom sort order possible) 
    }
    protected virtual void removeButton_Click(object sender, EventArgs e) {
      if (ItemsTreeView.SelectedNode == null) return;
      var selected = GetAllNodes(ItemsTreeView.SelectedNode);
      if (ItemCollection != null) {
        ItemCollection.RemoveRange(selected.Select(i => (T)i.Tag));
      } else {
        foreach (TreeNode item in selected)
          Content.Remove((T)item.Tag);
      }
      ItemsTreeView.SelectedNode = null;
    }
    #endregion

    #region CheckBox Events
    protected virtual void showDetailsCheckBox_CheckedChanged(object sender, EventArgs e) {
      if (showDetailsCheckBox.Checked) {
        splitContainer.Panel2Collapsed = false;
        detailsGroupBox.Enabled = ItemsTreeView.SelectedNode != null;
        viewHost.Content = ItemsTreeView.SelectedNode != null ? ItemsTreeView.SelectedNode.Tag as T : null;
      } else {
        splitContainer.Panel2Collapsed = true;
        viewHost.Content = null;
      }
    }
    #endregion

    #region Content Events
    protected virtual void Content_ItemsAdded(object sender, CollectionItemsChangedEventArgs<T> e) {
      if (InvokeRequired)
        Invoke(new CollectionItemsChangedEventHandler<T>(Content_ItemsAdded), sender, e);
      else {
        ItemsTreeView.BeginUpdate();
        foreach (T item in e.Items) AddTreeNodeRecursive(item, null);
        RebuildTreeImageList();
        ItemsTreeView.EndUpdate();
      }

    }
    protected virtual void Content_ItemsRemoved(object sender, CollectionItemsChangedEventArgs<T> e) {
      if (InvokeRequired)
        Invoke(new CollectionItemsChangedEventHandler<T>(Content_ItemsRemoved), sender, e);
      else {
        ItemsTreeView.BeginUpdate();
        foreach (T item in e.Items) {
          var treeNode = GetTreeNodeForItem(item);
          if (treeNode != null) RemoveTreeViewItem(treeNode);
        }
        RebuildTreeImageList();
        ItemsTreeView.EndUpdate();
      }
    }
    protected virtual void Content_CollectionReset(object sender, CollectionItemsChangedEventArgs<T> e) {
      if (InvokeRequired)
        Invoke(new CollectionItemsChangedEventHandler<T>(Content_CollectionReset), sender, e);
      else {
        ItemsTreeView.BeginUpdate();
        foreach (T item in e.OldItems) {
          var treeNode = GetTreeNodeForItem(item);
          if (treeNode != null) RemoveTreeViewItem(treeNode);
        }
        RebuildTreeImageList();
        foreach (T item in e.Items)
          AddTreeNodeRecursive(item, null);
        ItemsTreeView.EndUpdate();
      }
    }
    #endregion

    #region Item Events
    protected virtual void Item_ItemImageChanged(object sender, EventArgs e) {
      if (InvokeRequired)
        Invoke(new EventHandler(Item_ItemImageChanged), sender, e);
      else {
        var node = GetTreeNodeForItem(sender as T);
        if (node != null) UpdateTreeViewItemImage(node);
      }
    }
    protected virtual void Item_ToStringChanged(object sender, EventArgs e) {
      if (InvokeRequired)
        Invoke(new EventHandler(Item_ToStringChanged), sender, e);
      else {
        var item = sender as T;
        var itemNode = GetTreeNodeForItem(item);
        if (itemNode == null) return; //nothing to remove
        var parent = itemNode.Parent;
        ItemsTreeView.BeginUpdate();
        UpdateTreeNodeRecursive(item, parent);
        UpdateTreeViewItemText(itemNode);
        ItemsTreeView.EndUpdate();
      }
    }
    #endregion

    #region Helpers
    protected virtual void SortItemsTreeView() {
      ItemsTreeView.Sort();
      ItemsTreeView.Sorted = true;
    }
    protected virtual void RebuildTreeImageList() {
      if (ItemsTreeView.ImageList == null) ItemsTreeView.ImageList = new ImageList();
      ItemsTreeView.ImageList.Images.Clear();
      foreach (TreeNode treeNode in GetAllNodes(ItemsTreeView)) {
        T item = treeNode.Tag as T;
        try {
          ItemsTreeView.ImageList.Images.Add(item == null ? Common.Resources.VSImageLibrary.Nothing : item.ItemImage);
          treeNode.ImageIndex = ItemsTreeView.ImageList.Images.Count - 1;
          treeNode.SelectedImageIndex = treeNode.ImageIndex;
        }
        catch (ArgumentException) {
          treeNode.SelectedImageIndex = ItemsTreeView.ImageList.Images.Count + 10000;
        }
      }
    }
    protected List<TreeNode> GetAllNodes(TreeView view) {
      var n = new List<TreeNode>();
      foreach (TreeNode node in view.Nodes) {
        AddAllNodes(n, node);
      }
      return n;
    }
    private List<TreeNode> GetAllNodes(TreeNode node) {
      var n = new List<TreeNode>();
      AddAllNodes(n, node);
      return n;
    }
    private static void AddAllNodes(List<TreeNode> list, TreeNode node) {
      var queue = new Queue<TreeNode>(new[] { node });
      while (queue.Count > 0) {
        node = queue.Dequeue();
        if (!list.Contains(node)) list.Add(node);
        foreach (TreeNode n in node.Nodes)
          queue.Enqueue(n);
      }
    }
    protected T GetParent(T child) {
      return treeViewChildrenMapping.ContainsKey(child) ? treeViewChildrenMapping[child] : null;
    }
    private static IItem GetValue(object parent) {
      var props = parent.GetType().GetProperties();
      foreach (var prop in props) {
        if (prop.Name.Equals("Value", StringComparison.InvariantCultureIgnoreCase) || prop.Name.Equals("ActualValue", StringComparison.InvariantCultureIgnoreCase)) {
          if (typeof(IItem).IsAssignableFrom(prop.PropertyType)) {
            try { return prop.GetValue(parent) as IItem; }
            catch (TargetInvocationException) { }  //if getting the value is not an option (LookUpParameters,...) try other properties
          }
        }
      }
      return null;
    }
    protected List<T> GetChildren(T parent) {
      return treeViewChildrenMapping.Where(x => x.Value == parent).Select(x => x.Key).ToList();
    }
    #endregion
  }
}