#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2019 Nuclex Development Labs

This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.

This library 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
IBM Common Public License for more details.

You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

using Nuclex.Support.Collections;

namespace Nuclex.Windows.Forms {

  /// <summary>ListView allowing for other controls to be embedded in its cells</summary>
  /// <remarks>
  ///   <para>
  ///     There basically were two possible design choices: Provide a specialized
  ///     ListViewSubItem that carries a Control instead of a string or manage the
  ///     embedded controls seperate of the ListView's items.
  ///   </para>
  ///   <para>
  ///     The first option requires a complete rewrite of the ListViewItem class
  ///     and its related support classes, all of which are surprisingly large and
  ///     complex. Thus, I chose the less clean but more doable latter option.
  ///   </para>
  ///   <para>
  ///     This control is useful for simple item lists where you want to provide
  ///     a combobox, checkbox or other control to the user for a certain column.
  ///     It will not perform well for lists with hundreds of items since it
  ///     requires a control to be created per row and management of the embedded
  ///     controls is designed for limited usage.
  ///   </para>
  /// </remarks>
  public partial class ContainerListView : System.Windows.Forms.ListView {

    /// <summary>Message sent to a control to let it paint itself</summary>
    private const int WM_PAINT = 0x000F;

    /// <summary>Initializes a new ContainerListView</summary>
    public ContainerListView() {
      this.embeddedControlClickedDelegate = new EventHandler(embeddedControlClicked);

      this.embeddedControls = new ObservableList<ListViewEmbeddedControl>();
      this.embeddedControls.ItemAdded +=
        new EventHandler<ItemEventArgs<ListViewEmbeddedControl>>(embeddedControlAdded);
      this.embeddedControls.ItemRemoved +=
        new EventHandler<ItemEventArgs<ListViewEmbeddedControl>>(embeddedControlRemoved);
      this.embeddedControls.Clearing += new EventHandler(embeddedControlsClearing);

      InitializeComponent();
      
      // Eliminate flickering
      SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
      SetStyle(ControlStyles.AllPaintingInWmPaint, true);

      base.View = View.Details;

      this.columnHeaderHeight = Font.Height;
    }

    /// <summary>Controls being embedded in the ListView</summary>
    public ICollection<ListViewEmbeddedControl> EmbeddedControls {
      get { return this.embeddedControls; }
    }

    /// <summary>Updates the controls embeded into the list view</summary>
    public void UpdateEmbeddedControls() {
      if(View != View.Details) {
        for(int index = 0; index < this.embeddedControls.Count; ++index) {
          this.embeddedControls[index].Control.Visible = false;
        }
      } else {
        for(int index = 0; index < this.embeddedControls.Count; ++index) {
          ListViewEmbeddedControl embeddedControl = this.embeddedControls[index];

          Rectangle cellBounds = this.GetSubItemBounds(
            Items[embeddedControl.Row], embeddedControl.Column
          );

          bool intersectsColumnHeader =
            (base.HeaderStyle != ColumnHeaderStyle.None) &&
            (cellBounds.Top < base.Font.Height);

          embeddedControl.Control.Visible = !intersectsColumnHeader;
          embeddedControl.Control.Bounds = cellBounds;
        }
      }
    }

    /// <summary>Calculates the boundaries of a cell in the list view</summary>
    /// <param name="item">Item in the list view from which to calculate the cell</param>
    /// <param name="subItem">Index der cell whose boundaries to calculate</param>
    /// <returns>The boundaries of the specified list view cell</returns>
    /// <exception cref="IndexOutOfRangeException">
    ///   When the specified sub item index is not in the range of valid sub items
    /// </exception>
    protected Rectangle GetSubItemBounds(ListViewItem item, int subItem) {
      int[] order = GetColumnOrder();
      if(order == null) { // No Columns
        return Rectangle.Empty;
      }

      if(subItem >= order.Length) {
        throw new IndexOutOfRangeException("SubItem " + subItem + " out of range");
      }

      // Determine the border of the entire ListViewItem, including all sub items
      Rectangle itemBounds = item.GetBounds(ItemBoundsPortion.Entire);
      int subItemX = itemBounds.Left;

      // Find the horizontal position of the sub item. Because the column order can vary,
      // we need to use Columns[order[i]] instead of simply doing Columns[i] here!
      ColumnHeader columnHeader;
      int i;
      for(i = 0; i < order.Length; ++i) {
        columnHeader = this.Columns[order[i]];
        if(columnHeader.Index == subItem) {
          break;
        }

        subItemX += columnHeader.Width;
      }

      return new Rectangle(
        subItemX, itemBounds.Top, this.Columns[order[i]].Width, itemBounds.Height
      );
    }

    /// <summary>Responds to window messages sent by the operating system</summary>
    /// <param name="message">Window message that will be processed</param>
    protected override void WndProc(ref Message message) {
      switch(message.Msg) {
        case WM_PAINT: {
          UpdateEmbeddedControls();
          break;
        }
      }

      base.WndProc(ref message);
    }

    /// <summary>Called when the list of embedded controls has been cleared</summary>
    /// <param name="sender">Collection that has been cleared of its controls</param>
    /// <param name="arguments">Not used</param>
    private void embeddedControlsClearing(object sender, EventArgs arguments) {
      this.BeginUpdate();
      try {
        foreach(ListViewEmbeddedControl embeddedControl in this.embeddedControls) {
          embeddedControl.Control.Click -= this.embeddedControlClickedDelegate;
          this.Controls.Remove(embeddedControl.Control);
        }
      }
      finally {
        this.EndUpdate();
      }
    }

    /// <summary>Called when a control gets removed from  the embedded controls list</summary>
    /// <param name="sender">List from which the control has been removed</param>
    /// <param name="arguments">
    ///   Event arguments providing a reference to the removed control
    /// </param>
    private void embeddedControlAdded(
      object sender, ItemEventArgs<ListViewEmbeddedControl> arguments
    ) {
      arguments.Item.Control.Click += this.embeddedControlClickedDelegate;
      this.Controls.Add(arguments.Item.Control);
    }

    /// <summary>Called when a control gets added to the embedded controls list</summary>
    /// <param name="sender">List to which the control has been added</param>
    /// <param name="arguments">
    ///   Event arguments providing a reference to the added control
    /// </param>
    private void embeddedControlRemoved(
      object sender, ItemEventArgs<ListViewEmbeddedControl> arguments
    ) {
      if(this.Controls.Contains(arguments.Item.Control)) {
        arguments.Item.Control.Click -= this.embeddedControlClickedDelegate;
        this.Controls.Remove(arguments.Item.Control);
      }
    }

    /// <summary>Called when an embedded control has been clicked on</summary>
    /// <param name="sender">Embedded control that has been clicked</param>
    /// <param name="arguments">Not used</param>
    private void embeddedControlClicked(object sender, EventArgs arguments) {
      this.BeginUpdate();

      try {
        SelectedItems.Clear();

        foreach(ListViewEmbeddedControl embeddedControl in this.embeddedControls) {
          if(ReferenceEquals(embeddedControl.Control, sender)) {
            if((embeddedControl.Row > 0) && (embeddedControl.Row < Items.Count)) {
              Items[embeddedControl.Row].Selected = true;
            }
          }
        }
      }
      finally {
        this.EndUpdate();
      }
    }

    /// <summary>Obtains the current column order of the list</summary>
    /// <returns>An array indicating the order of the list's columns</returns>
    private int[] GetColumnOrder() {
      int[] order = new int[this.Columns.Count];

      for(int index = 0; index < this.Columns.Count; ++index) {
        order[this.Columns[index].DisplayIndex] = index;
      }

      return order;
    }

    /// <summary>Height of the list view's column header</summary>
    private int columnHeaderHeight;
    /// <summary>Event handler for when embedded controls are clicked on</summary>
    private EventHandler embeddedControlClickedDelegate;
    /// <summary>Controls being embedded in this ListView</summary>
    private ObservableList<ListViewEmbeddedControl> embeddedControls;

  }

} // namespace Nuclex.Windows.Forms