using NStack;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.Linq;
using Terminal.Gui;

namespace UICatalog {
	/// <summary>
	/// Main program for the Terminal.gui UI Catalog app. This app provides a chooser that allows
	/// for a calalog of UI demos, examples, and tests.
	/// </summary>
	internal class Program {
		private static Toplevel _top;
		private static MenuBar _menu;
		private static int _nameColumnWidth;
		private static Window _leftPane;
		private static List<string> _categories;
		private static ListView _categoryListView;
		private static Window _rightPane;
		private static List<Type> _scenarios;
		private static ListView _scenarioListView;
		private static StatusBar _statusBar;

		private static Scenario _selectedScenario = null;

		static void Main (string [] args)
		{
			if (Debugger.IsAttached)
				CultureInfo.DefaultThreadCurrentUICulture = CultureInfo.GetCultureInfo ("en-US");

			_scenarios = Scenario.GetDerivedClassesCollection ().OrderBy (t => Scenario.ScenarioMetadata.GetName (t)).ToList();

			if (args.Length > 0) {
				var item = _scenarios.FindIndex (t => Scenario.ScenarioMetadata.GetName (t).Equals (args [0], StringComparison.OrdinalIgnoreCase));
				_selectedScenario = (Scenario)Activator.CreateInstance (_scenarios [item]);
				_selectedScenario.Init (Application.Top);
				_selectedScenario.Setup ();
				_selectedScenario.Run ();
				_selectedScenario = null;
				return;
			}

			Scenario scenario = GetScenarioToRun ();
			while (scenario != null) {
				scenario.Init (Application.Top);
				scenario.Setup ();
				scenario.Run ();
				scenario = GetScenarioToRun ();
			}

		}

		/// <summary>
		/// Create all controls. This gets called once and the controls remain with their state between Sceanrio runs.
		/// </summary>
		private static void Setup ()
		{
			_menu = new MenuBar (new MenuBarItem [] {
				new MenuBarItem ("_File", new MenuItem [] {
					new MenuItem ("_Quit", "", () => Application.RequestStop() )
				}),
				new MenuBarItem ("_About...", "About this app", () =>  MessageBox.Query (0, 10, "About UI Catalog", "UI Catalog is a comprehensive sample library for Terminal.Gui", "Ok")),
			});

			_leftPane = new Window ("Categories") {
				X = 0,
				Y = 1, // for menu
				Width = 25,
				Height = Dim.Fill (),
				CanFocus = false,
			};


			_categories = Scenario.GetAllCategories ().OrderBy(c => c).ToList();
			_categoryListView = new ListView (_categories) {
				X = 1,
				Y = 0,
				Width = Dim.Fill (0),
				Height = Dim.Fill (2),
				AllowsMarking = false,
				CanFocus = true,
			};
			_categoryListView.OpenSelectedItem += (o, a) => {
				_top.SetFocus (_rightPane);
			};
			_categoryListView.SelectedChanged += CategoryListView_SelectedChanged;
			_leftPane.Add (_categoryListView);

			_rightPane = new Window ("Scenarios") {
				X = 25,
				Y = 1, // for menu
				Width = Dim.Fill (),
				Height = Dim.Fill (),
				CanFocus = false,

			};

			_nameColumnWidth = Scenario.ScenarioMetadata.GetName (_scenarios.OrderByDescending (t => Scenario.ScenarioMetadata.GetName (t).Length).FirstOrDefault ()).Length;

			_scenarioListView = new ListView () {
				X = 0,
				Y = 0,
				Width = Dim.Fill (0),
				Height = Dim.Fill (0),
				AllowsMarking = false,
				CanFocus = true,
			};

			//_scenarioListView.OnKeyPress += (KeyEvent ke) => {
			//	if (_top.MostFocused == _scenarioListView && ke.Key == Key.Enter) {
			//		_scenarioListView_OpenSelectedItem (null, null);
			//	}
			//};

			_scenarioListView.OpenSelectedItem += _scenarioListView_OpenSelectedItem;
			_rightPane.Add (_scenarioListView);

			_categoryListView.SelectedItem = 0;
			_categoryListView.OnSelectedChanged ();

			_statusBar = new StatusBar (new StatusItem [] {
				//new StatusItem(Key.F1, "~F1~ Help", () => Help()),
				new StatusItem(Key.ControlQ, "~CTRL-Q~ Quit", () => {
					if (_selectedScenario is null){
						// This causes GetScenarioToRun to return null
						_selectedScenario = null;
						Application.RequestStop();
					} else {
						_selectedScenario.RequestStop();
					}
				}),
			});
		}

		/// <summary>
		/// This shows the selection UI. Each time it is run, it calls Application.Init to reset everything.
		/// </summary>
		/// <returns></returns>
		private static Scenario GetScenarioToRun ()
		{
			Application.Init ();

			if (_menu == null) {
				Setup ();
			}

			_top = Application.Top;

			_top.KeyUp += KeyUpHandler;

			_top.Add (_menu);
			_top.Add (_leftPane);
			_top.Add (_rightPane);
			_top.Add (_statusBar);

			// HACK: There is no other way to SetFocus before Application.Run. See Issue #445
#if false
			if (_runningScenario != null)
				Application.Iteration += Application_Iteration;
#else
			_top.Ready += (o, a) => {
				if (_selectedScenario != null) {
					_top.SetFocus (_rightPane);
					_selectedScenario = null;
				}
			};
#endif
			
			Application.Run (_top);
			Application.Shutdown ();
			return _selectedScenario;
		}

#if false
		private static void Application_Iteration (object sender, EventArgs e)
		{
			Application.Iteration -= Application_Iteration;
			_top.SetFocus (_rightPane);
		}
#endif
		private static void _scenarioListView_OpenSelectedItem (object sender, EventArgs e)
		{
			if (_selectedScenario is null) {
				var source = _scenarioListView.Source as ScenarioListDataSource;
				_selectedScenario = (Scenario)Activator.CreateInstance (source.Scenarios [_scenarioListView.SelectedItem]);
				Application.RequestStop ();
			}
		}

		internal class ScenarioListDataSource : IListDataSource {
			public List<Type> Scenarios { get; set; }

			public bool IsMarked (int item) => false;//  Scenarios [item].IsMarked;

			public int Count => Scenarios.Count;

			public ScenarioListDataSource (List<Type> itemList) => Scenarios = itemList;

			public void Render (ListView container, ConsoleDriver driver, bool selected, int item, int col, int line, int width)
			{
				container.Move (col, line);
				// Equivalent to an interpolated string like $"{Scenarios[item].Name, -widtestname}"; if such a thing were possible
				var s = String.Format (String.Format ("{{0,{0}}}", -_nameColumnWidth), Scenario.ScenarioMetadata.GetName (Scenarios [item]));
				RenderUstr (driver, $"{s}  {Scenario.ScenarioMetadata.GetDescription (Scenarios [item])}", col, line, width);
			}

			public void SetMark (int item, bool value)
			{
			}

			// A slightly adapted method from: https://github.com/migueldeicaza/gui.cs/blob/fc1faba7452ccbdf49028ac49f0c9f0f42bbae91/Terminal.Gui/Views/ListView.cs#L433-L461
			private void RenderUstr (ConsoleDriver driver, ustring ustr, int col, int line, int width)
			{
				int used = 0;
				int index = 0;
				while (index < ustr.Length) {
					(var rune, var size) = Utf8.DecodeRune (ustr, index, index - ustr.Length);
					var count = Rune.ColumnWidth (rune);
					if (used + count >= width) break;
					driver.AddRune (rune);
					used += count;
					index += size;
				}

				while (used < width) {
					driver.AddRune (' ');
					used++;
				}
			}

			public IList ToList ()
			{
				return Scenarios;
			}

		}

		/// <summary>
		/// When Scenarios are running we need to override the behavior of the Menu 
		/// and Statusbar to enable Scenarios that use those (or related key input)
		/// to not be impacted. Same as for tabs.
		/// </summary>
		/// <param name="ke"></param>
		private static void KeyUpHandler (object sender, View.KeyEventEventArgs a)
		{
			if (_selectedScenario != null) {
				//switch (ke.Key) {
				//case Key.Esc:
				//	//_runningScenario.RequestStop ();
				//	break;
				//case Key.Enter:
				//	break;
				//}<
			} else if (a.KeyEvent.Key == Key.Tab || a.KeyEvent.Key == Key.BackTab) {
				// BUGBUG: Work around Issue #434 by implementing our own TAB navigation
				if (_top.MostFocused == _categoryListView)
					_top.SetFocus (_rightPane);
				else
					_top.SetFocus (_leftPane);
			}
		}

		private static void CategoryListView_SelectedChanged (object sender, ListViewItemEventArgs e)
		{
			var item = _categories [_categoryListView.SelectedItem];
			List<Type> newlist;
			if (item.Equals ("All")) {
				newlist = _scenarios;

			} else {
				newlist = _scenarios.Where (t => Scenario.ScenarioCategory.GetCategories (t).Contains (item)).ToList ();
			}
			_scenarioListView.Source = new ScenarioListDataSource (newlist);
			_scenarioListView.SelectedItem = 0;
		}
	}
}