//
//  ListBox.cs
//
//  Author:
//       Jean-Philippe Bruyère <jp.bruyere@hotmail.com>
//
//  Copyright (c) 2015 jp
//
//  This program 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.
//
//  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
using System;
using System.Collections;
using System.Xml.Serialization;
using System.ComponentModel;
using System.IO;
using System.Diagnostics;
using System.Xml;
using System.Collections.Generic;
using System.Threading;

namespace Crow
{
	public class ListBox : TemplatedControl
	{
		#region CTOR
		public ListBox () : base() {}
		#endregion

		#region events
		public event EventHandler<SelectionChangeEventArgs> SelectedItemChanged;
		#endregion

		Group _list;
		GenericStack _gsList;
		IList data;
		int _selectedIndex;
		int itemPerPage = 50;
		Thread loadingThread = null;
		volatile bool cancelLoading = false;

		[XmlAttributeAttribute]public IList Data {
			get {
				return data;
			}
			set {
				if (value == data)
					return;
				
				cancelLoadingThread ();

				data = value;

				NotifyValueChanged ("Data", data);

				lock (CurrentInterface.UpdateMutex)
					_list.ClearChildren ();
				if (_gsList.Orientation == Orientation.Horizontal)
					_gsList.Width = -1;
				else
					_gsList.Height = -1;

				if (data == null)
					return;

				loadingThread = new Thread (loading);
				loadingThread.IsBackground = true;
				loadingThread.Start ();
				//loadPage(1);

				NotifyValueChanged ("SelectedIndex", _selectedIndex);
				NotifyValueChanged ("SelectedItem", SelectedItem);
				SelectedItemChanged.Raise (this, new SelectionChangeEventArgs (SelectedItem));
			}
		}

		[XmlAttributeAttribute][DefaultValue(-1)]public int SelectedIndex{
			get { return _selectedIndex; }
			set { 
				if (value == _selectedIndex)
					return;

				_selectedIndex = value; 

				NotifyValueChanged ("SelectedIndex", _selectedIndex);
				NotifyValueChanged ("SelectedItem", SelectedItem);
				SelectedItemChanged.Raise (this, new SelectionChangeEventArgs (SelectedItem));
			}
		}
		[XmlIgnore]public virtual object SelectedItem{
			get { return data == null ? null : _selectedIndex < 0 ? null : data[_selectedIndex]; }
		}
		protected void raiseSelectedItemChanged(){
			SelectedItemChanged.Raise (this, new SelectionChangeEventArgs (SelectedItem));
		}
			
		#region TemplatedControl override
		protected override void loadTemplate (GraphicObject template = null)
		{
			base.loadTemplate (template);
			_list = this.child.FindByName ("List") as Group;
			if (_list == null)
				throw new Exception ("ListBox Template MUST contain a Goup widget named 'List'.");
			_gsList = _list as GenericStack;
		}
		#endregion

		void loading(){
			if (ItemTemplates == null)
				ItemTemplates = new Dictionary<string, ItemTemplate> ();
			if (!ItemTemplates.ContainsKey ("default"))
				ItemTemplates ["default"] = Interface.GetItemTemplate (ItemTemplate);

			for (int i = 1; i <= (data.Count / itemPerPage) + 1; i++) {
				if (cancelLoading)
					return;
				loadPage (i);
			}
		}
		void cancelLoadingThread(){
			if (loadingThread == null)
				return;
			if (!loadingThread.IsAlive)
				return;			
			cancelLoading = true;
			loadingThread.Join ();
			cancelLoading = false;
		}
		void loadPage(int pageNum)
		{
			#if DEBUG_LOAD
			Stopwatch loadingTime = new Stopwatch ();
			loadingTime.Start ();
			#endif

			Group page = _list.Clone () as Group;
			
			page.Name = "page" + pageNum;

			//reset size to fit in the dir of the stacking
			//because _list total size is forced to approx size
			if (_gsList.Orientation == Orientation.Horizontal) {
				page.Width = Measure.Fit;
				page.BindMember ("Height", "../HeightPolicy");
			} else {
				page.Height = Measure.Fit;
				page.BindMember ("Width", "../WidthPolicy");
			}

			for (int i = (pageNum - 1) * itemPerPage; i < pageNum * itemPerPage; i++) {
				if (i >= data.Count)
					break;
				if (cancelLoading)
					return;
				
				loadItem (i, page);

				//g.LogicalParent = this;
			}

			lock (CurrentInterface.LayoutMutex)
				_list.AddChild (page);

			#if DEBUG_LOAD
			loadingTime.Stop ();
			Debug.WriteLine("Listbox {2} Loading: {0} ticks \t, {1} ms",
			loadingTime.ElapsedTicks,
			loadingTime.ElapsedMilliseconds, this.ToString());
			#endif
		}
		protected void loadItem(int i, Group page){
			GraphicObject g = null;
			ItemTemplate iTemp = null;
			Type dataType = data [i].GetType ();

			if (ItemTemplates.ContainsKey (dataType.FullName))
				iTemp = ItemTemplates [dataType.FullName];
			else
				iTemp = ItemTemplates ["default"];

			lock (CurrentInterface.LayoutMutex) {
				g = iTemp.CreateInstance(CurrentInterface);
				page.AddChild (g);
				g.DataSource = data [i];
			}

			registerItemClick (g);

			if (iTemp.Expand != null && g is Expandable) {
				(g as Expandable).Expand += iTemp.Expand;
			}			
		}
		protected virtual void registerItemClick(GraphicObject g){
			g.MouseClick += itemClick;
		}
		protected void _list_LayoutChanged (object sender, LayoutingEventArgs e)
		{
#if DEBUG_LAYOUTING
			Debug.WriteLine("list_LayoutChanged");
#endif
			if (_gsList.Orientation == Orientation.Horizontal) {
				if (e.LayoutType == LayoutingType.Width)
					_gsList.Width = approxSize;
			} else if (e.LayoutType == LayoutingType.Height)
				_gsList.Height = approxSize;
		}
		int approxSize
		{
			get {
				if (data == null)
					return -1;
				GenericStack page1 = _list.FindByName ("page1") as GenericStack;
				if (page1 == null)
					return -1;
				
				return page1.Orientation == Orientation.Horizontal ?
					data.Count < itemPerPage ?
						-1:
					(int)Math.Ceiling ((double)page1.Slot.Width / (double)itemPerPage * (double)(data.Count+1)):
					data.Count < itemPerPage ?
						-1:
					(int)Math.Ceiling ((double)page1.Slot.Height / (double)itemPerPage * (double)(data.Count+1));
			}
		}
		internal virtual void itemClick(object sender, MouseButtonEventArgs e){
			SelectedIndex = data.IndexOf((sender as GraphicObject).DataSource);
		}
	}
}