using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Terminal.Gui;

namespace UICatalog.Scenarios {
	[ScenarioMetadata (Name: "TreeViewFileSystem", Description: "Hierarchical file system explorer based on TreeView")]
	[ScenarioCategory ("Controls")]
	class TreeViewFileSystem : Scenario {

		/// <summary>
		/// A tree view where nodes are files and folders
		/// </summary>
		TreeView<FileSystemInfo> treeViewFiles;

		MenuItem miShowLines;
		private MenuItem miPlusMinus;
		private MenuItem miArrowSymbols;
		private MenuItem miNoSymbols;
		private MenuItem miColoredSymbols;
		private MenuItem miInvertSymbols;
		private MenuItem miUnicodeSymbols;
		private MenuItem miFullPaths;
		private Terminal.Gui.Attribute green;
		private Terminal.Gui.Attribute red;

		public override void Setup ()
		{
			Win.Title = this.GetName();
			Win.Y = 1; // menu
			Win.Height = Dim.Fill (1); // status bar
			Top.LayoutSubviews ();
			
			var menu = new MenuBar (new MenuBarItem [] {
				new MenuBarItem ("_File", new MenuItem [] {
					new MenuItem ("_Quit", "", () => Quit()),
				}),
				new MenuBarItem ("_View", new MenuItem [] {
					miShowLines = new MenuItem ("_ShowLines", "", () => ShowLines()){
					Checked = true, CheckType = MenuItemCheckStyle.Checked
						},
					null /*separator*/,
					miPlusMinus = new MenuItem ("_PlusMinusSymbols", "", () => SetExpandableSymbols('+','-')){Checked = true, CheckType = MenuItemCheckStyle.Radio},
					miArrowSymbols = new MenuItem ("_ArrowSymbols", "", () => SetExpandableSymbols('>','v')){Checked = false, CheckType = MenuItemCheckStyle.Radio},
					miNoSymbols = new MenuItem ("_NoSymbols", "", () => SetExpandableSymbols(null,null)){Checked = false, CheckType = MenuItemCheckStyle.Radio},
					miUnicodeSymbols = new MenuItem ("_Unicode", "", () => SetExpandableSymbols('ஹ','﷽')){Checked = false, CheckType = MenuItemCheckStyle.Radio},
					null /*separator*/,
					miColoredSymbols = new MenuItem ("_ColoredSymbols", "", () => ShowColoredExpandableSymbols()){Checked = false, CheckType = MenuItemCheckStyle.Checked},
					miInvertSymbols = new MenuItem ("_InvertSymbols", "", () => InvertExpandableSymbols()){Checked = false, CheckType = MenuItemCheckStyle.Checked},
					miFullPaths = new MenuItem ("_FullPaths", "", () => SetFullName()){Checked = false, CheckType = MenuItemCheckStyle.Checked},
				}),
			});
			Top.Add (menu);

			var statusBar = new StatusBar (new StatusItem [] {
				new StatusItem(Key.CtrlMask | Key.Q, "~^Q~ Quit", () => Quit()),
			});
			Top.Add (statusBar);

			var lblFiles = new Label("File Tree:"){
				X=0,
				Y=1
			};
			Win.Add(lblFiles);

			treeViewFiles = new TreeView<FileSystemInfo> () {
				X = 0,
				Y = Pos.Bottom(lblFiles),
				Width = Dim.Fill(),
				Height = Dim.Fill(),
			};
			
			SetupFileTree();

			Win.Add(treeViewFiles);
			
			SetupScrollBar();
						
			green = Application.Driver.MakeAttribute (Color.Green, Color.Blue);			
			red = Application.Driver.MakeAttribute (Color.Red, Color.Blue);
		}

		private void SetupScrollBar ()
		{
			var _scrollBar = new ScrollBarView (treeViewFiles, true);

			_scrollBar.ChangedPosition += () => {
				treeViewFiles.ScrollOffset = _scrollBar.Position;
				if (treeViewFiles.ScrollOffset != _scrollBar.Position) {
					_scrollBar.Position = treeViewFiles.ScrollOffset;
				}
				treeViewFiles.SetNeedsDisplay ();
			};
			/*
			_scrollBar.OtherScrollBarView.ChangedPosition += () => {
				_listView.LeftItem = _scrollBar.OtherScrollBarView.Position;
				if (_listView.LeftItem != _scrollBar.OtherScrollBarView.Position) {
					_scrollBar.OtherScrollBarView.Position = _listView.LeftItem;
				}
				_listView.SetNeedsDisplay ();
			};*/
			
			treeViewFiles.DrawContent += (e) => {
				_scrollBar.Size = treeViewFiles.ContentHeight;
				_scrollBar.Position = treeViewFiles.ScrollOffset;
			//	_scrollBar.OtherScrollBarView.Size = _listView.Maxlength - 1;
			//	_scrollBar.OtherScrollBarView.Position = _listView.LeftItem;
				_scrollBar.Refresh ();
			};
		}

		private void SetupFileTree ()
		{
			
			// setup delegates
			treeViewFiles.TreeBuilder = new DelegateTreeBuilder<FileSystemInfo>(

				// Determines how to compute children of any given branch
				GetChildren,
				// As a shortcut to enumerating half the file system, tell tree that all directories are expandable (even if they turn out to be empty later on)				
				(o)=>o is DirectoryInfo
			);

			// Determines how to represent objects as strings on the screen
			treeViewFiles.AspectGetter = FileSystemAspectGetter;

			treeViewFiles.AddObjects(DriveInfo.GetDrives().Select(d=>d.RootDirectory));
		}

		private void ShowLines ()
		{
			miShowLines.Checked = !miShowLines.Checked;

			treeViewFiles.Style.ShowBranchLines = miShowLines.Checked;
			treeViewFiles.SetNeedsDisplay();
		}
		
		private void SetExpandableSymbols(Rune? expand, Rune? collapse)
		{
			miPlusMinus.Checked = expand == '+';
			miArrowSymbols.Checked = expand == '>';
			miNoSymbols.Checked = expand == null;
			miUnicodeSymbols.Checked = expand == 'ஹ';
						
			treeViewFiles.Style.ExpandableSymbol = expand;
			treeViewFiles.Style.CollapseableSymbol = collapse;
			treeViewFiles.SetNeedsDisplay();
		}
		private void ShowColoredExpandableSymbols()
		{
			miColoredSymbols.Checked = !miColoredSymbols.Checked;

			treeViewFiles.Style.ColorExpandSymbol =  miColoredSymbols.Checked;
			treeViewFiles.SetNeedsDisplay();
		}
		private void InvertExpandableSymbols(){
			miInvertSymbols.Checked = !miInvertSymbols.Checked;

			treeViewFiles.Style.InvertExpandSymbolColors =  miInvertSymbols.Checked;
			treeViewFiles.SetNeedsDisplay();
		}

		private void SetFullName()
		{
			miFullPaths.Checked = !miFullPaths.Checked;

			if(miFullPaths.Checked)
				treeViewFiles.AspectGetter = (f)=>f.FullName;
			else
				treeViewFiles.AspectGetter = (f)=>f.Name;
		}


		private IEnumerable<FileSystemInfo> GetChildren(FileSystemInfo model)
		{
			// If it is a directory it's children are all contained files and dirs
			if(model is DirectoryInfo d) {
				try {
					return d.GetFileSystemInfos()
						//show directories first
						.OrderBy(a=>a is DirectoryInfo ? 0:1)
						.ThenBy(b=>b.Name);
				}
				catch(SystemException) {

					// Access violation or other error getting the file list for directory
					return Enumerable.Empty<FileSystemInfo>();
				}
			}

		    return Enumerable.Empty<FileSystemInfo>();;
		}
		private string FileSystemAspectGetter(FileSystemInfo model)
		{
			if(model is DirectoryInfo d)
				return d.Name;
			if(model is FileInfo f)
				return f.Name;

			return model.ToString();
		}

		private void Quit ()
		{
			Application.RequestStop ();
		}
	}
}