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

namespace UICatalog.Scenarios {
	[ScenarioMetadata (Name: "File System Explorer", Description: "Hierarchical file system explorer demonstrating TreeView.")]
	[ScenarioCategory ("Controls"), ScenarioCategory ("TreeView"), ScenarioCategory ("Files and IO")]
	public class TreeViewFileSystem : Scenario {

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

		MenuItem miShowLines;
		private MenuItem _miPlusMinus;
		private MenuItem _miArrowSymbols;
		private MenuItem _miNoSymbols;
		private MenuItem _miColoredSymbols;
		private MenuItem _miInvertSymbols;

		private MenuItem _miBasicIcons;
		private MenuItem _miUnicodeIcons;
		private MenuItem _miNerdIcons;

		private MenuItem _miFullPaths;
		private MenuItem _miLeaveLastRow;
		private MenuItem _miHighlightModelTextOnly;
		private MenuItem _miCustomColors;
		private MenuItem _miCursor;
		private MenuItem _miMultiSelect;

		private DetailsFrame _detailsFrame;
		private FileSystemIconProvider _iconProvider = new ();

		public override void Setup ()
		{
			Win.Title = this.GetName ();
			Win.Y = 1; // menu
			Win.Height = Dim.Fill ();
			Application.Top.LayoutSubviews ();

			var menu = new MenuBar (new MenuBarItem [] {
				new MenuBarItem ("_File", new MenuItem [] {
					new MenuItem ("_Quit", $"{Application.QuitKey}", () => Quit()),
				}),
				new MenuBarItem ("_View", new MenuItem [] {
					_miFullPaths = new MenuItem ("_Full Paths", "", () => SetFullName()){Checked = false, CheckType = MenuItemCheckStyle.Checked},
					_miMultiSelect = new MenuItem ("_Multi Select", "", () => SetMultiSelect()){Checked = true, CheckType = MenuItemCheckStyle.Checked},
				}),
				new MenuBarItem ("_Style", new MenuItem [] {
					miShowLines = new MenuItem ("_Show Lines", "", () => ShowLines()){
					Checked = true, CheckType = MenuItemCheckStyle.Checked
						},
					null /*separator*/,
					_miPlusMinus = new MenuItem ("_Plus Minus Symbols", "+ -", () => SetExpandableSymbols((Rune)'+',(Rune)'-')){Checked = true, CheckType = MenuItemCheckStyle.Radio},
					_miArrowSymbols = new MenuItem ("_Arrow Symbols", "> v", () => SetExpandableSymbols((Rune)'>',(Rune)'v')){Checked = false, CheckType = MenuItemCheckStyle.Radio},
					_miNoSymbols = new MenuItem ("_No Symbols", "", () => SetExpandableSymbols(default,null)){Checked = false, CheckType = MenuItemCheckStyle.Radio},
					null /*separator*/,
					_miColoredSymbols = new MenuItem ("_Colored Symbols", "", () => ShowColoredExpandableSymbols()){Checked = false, CheckType = MenuItemCheckStyle.Checked},
					_miInvertSymbols = new MenuItem ("_Invert Symbols", "", () => InvertExpandableSymbols()){Checked = false, CheckType = MenuItemCheckStyle.Checked},
					null /*separator*/,
					_miBasicIcons = new MenuItem ("_Basic Icons",null, SetNoIcons){Checked = false, CheckType = MenuItemCheckStyle.Radio},
					_miUnicodeIcons = new MenuItem ("_Unicode Icons", null, SetUnicodeIcons){Checked = false, CheckType = MenuItemCheckStyle.Radio},
					_miNerdIcons = new MenuItem ("_Nerd Icons", null, SetNerdIcons){Checked = false, CheckType = MenuItemCheckStyle.Radio},
					null /*separator*/,
					_miLeaveLastRow = new MenuItem ("_Leave Last Row", "", () => SetLeaveLastRow()){Checked = true, CheckType = MenuItemCheckStyle.Checked},
					_miHighlightModelTextOnly = new MenuItem ("_Highlight Model Text Only", "", () => SetCheckHighlightModelTextOnly()){Checked = false, CheckType = MenuItemCheckStyle.Checked},
					null /*separator*/,
					_miCustomColors = new MenuItem ("C_ustom Colors Hidden Files", "Yellow/Red", () => SetCustomColors()){Checked = false, CheckType = MenuItemCheckStyle.Checked},
					null /*separator*/,
					_miCursor = new MenuItem ("Curs_or (MultiSelect only)", "", () => SetCursor()){Checked = false, CheckType = MenuItemCheckStyle.Checked},
				}),
			});
			Application.Top.Add (menu);

			treeViewFiles = new TreeView<IFileSystemInfo> () {
				X = 0,
				Y = 0,
				Width = Dim.Percent (50),
				Height = Dim.Fill (),
			};
			treeViewFiles.DrawLine += TreeViewFiles_DrawLine;

			_detailsFrame = new DetailsFrame (_iconProvider) {
				X = Pos.Right (treeViewFiles),
				Y = 0,
				Width = Dim.Fill (),
				Height = Dim.Fill (),
			};

			Win.Add (_detailsFrame);
			treeViewFiles.MouseClick += TreeViewFiles_MouseClick;
			treeViewFiles.KeyPress += TreeViewFiles_KeyPress;
			treeViewFiles.SelectionChanged += TreeViewFiles_SelectionChanged;

			SetupFileTree ();

			Win.Add (treeViewFiles);
			treeViewFiles.GoToFirst ();
			treeViewFiles.Expand ();

			SetupScrollBar ();

			treeViewFiles.SetFocus ();

			UpdateIconCheckedness ();
		}

		private void SetNoIcons ()
		{
			_iconProvider.UseUnicodeCharacters = false;
			_iconProvider.UseNerdIcons = false;
			UpdateIconCheckedness ();
		}

		private void SetUnicodeIcons ()
		{
			_iconProvider.UseUnicodeCharacters = true;
			UpdateIconCheckedness ();
		}
		private void SetNerdIcons ()
		{
			_iconProvider.UseNerdIcons = true;
			UpdateIconCheckedness ();
		}
		private void UpdateIconCheckedness ()
		{
			_miBasicIcons.Checked = !_iconProvider.UseNerdIcons && !_iconProvider.UseUnicodeCharacters;
			_miUnicodeIcons.Checked = _iconProvider.UseUnicodeCharacters;
			_miNerdIcons.Checked = _iconProvider.UseNerdIcons;
			treeViewFiles.SetNeedsDisplay ();
		}

		private void TreeViewFiles_SelectionChanged (object sender, SelectionChangedEventArgs<IFileSystemInfo> e)
		{
			ShowPropertiesOf (e.NewValue);
		}

		private void TreeViewFiles_DrawLine (object sender, DrawTreeViewLineEventArgs<IFileSystemInfo> e)
		{
			// Render directory icons in yellow
			if (e.Model is IDirectoryInfo d) {
				if (_iconProvider.UseNerdIcons || _iconProvider.UseUnicodeCharacters) {
					if (e.IndexOfModelText > 0 && e.IndexOfModelText < e.RuneCells.Count) {
						var cell = e.RuneCells [e.IndexOfModelText];
						cell.ColorScheme = new ColorScheme (
							new Terminal.Gui.Attribute (
								Color.BrightYellow,
								cell.ColorScheme.Normal.Background)
						);
					}
				}
			}
		}

		private void TreeViewFiles_KeyPress (object sender, KeyEventEventArgs obj)
		{
			if (obj.KeyEvent.Key == (Key.R | Key.CtrlMask)) {

				var selected = treeViewFiles.SelectedObject;

				// nothing is selected
				if (selected == null)
					return;

				var location = treeViewFiles.GetObjectRow (selected);

				//selected object is offscreen or somehow not found
				if (location == null || location < 0 || location > treeViewFiles.Frame.Height)
					return;

				ShowContextMenu (new Point (
					5 + treeViewFiles.Frame.X,
					location.Value + treeViewFiles.Frame.Y + 2),
					selected);
			}
		}

		private void TreeViewFiles_MouseClick (object sender, MouseEventEventArgs obj)
		{
			// if user right clicks
			if (obj.MouseEvent.Flags.HasFlag (MouseFlags.Button3Clicked)) {

				var rightClicked = treeViewFiles.GetObjectOnRow (obj.MouseEvent.Y);

				// nothing was clicked
				if (rightClicked == null)
					return;

				ShowContextMenu (new Point (
					obj.MouseEvent.X + treeViewFiles.Frame.X,
					obj.MouseEvent.Y + treeViewFiles.Frame.Y + 2),
					rightClicked);
			}
		}

		private void ShowContextMenu (Point screenPoint, IFileSystemInfo forObject)
		{
			var menu = new ContextMenu ();
			menu.Position = screenPoint;

			menu.MenuItems = new MenuBarItem (new [] { new MenuItem ("Properties", null, () => ShowPropertiesOf (forObject)) });

			Application.MainLoop.Invoke (menu.Show);
		}

		class DetailsFrame : FrameView {
			private IFileSystemInfo fileInfo;
			private FileSystemIconProvider _iconProvider;

			public DetailsFrame (FileSystemIconProvider iconProvider)
			{
				Title = "Details";
				Visible = true;
				CanFocus = true;
				_iconProvider = iconProvider;
			}

			public IFileSystemInfo FileInfo {
				get => fileInfo; set {
					fileInfo = value;
					System.Text.StringBuilder sb = null;

					if (fileInfo is IFileInfo f) {
						Title = $"{_iconProvider.GetIconWithOptionalSpace (f)}{f.Name}".Trim ();
						sb = new System.Text.StringBuilder ();
						sb.AppendLine ($"Path:\n {f.FullName}\n");
						sb.AppendLine ($"Size:\n {f.Length:N0} bytes\n");
						sb.AppendLine ($"Modified:\n {f.LastWriteTime}\n");
						sb.AppendLine ($"Created:\n {f.CreationTime}");
					}

					if (fileInfo is IDirectoryInfo dir) {
						Title = $"{_iconProvider.GetIconWithOptionalSpace (dir)}{dir.Name}".Trim ();
						sb = new System.Text.StringBuilder ();
						sb.AppendLine ($"Path:\n {dir?.FullName}\n");
						sb.AppendLine ($"Modified:\n {dir.LastWriteTime}\n");
						sb.AppendLine ($"Created:\n {dir.CreationTime}\n");
					}
					Text = sb.ToString ();
				}
			}
		}

		private void ShowPropertiesOf (IFileSystemInfo fileSystemInfo)
		{
			_detailsFrame.FileInfo = fileSystemInfo;
		}

		private void SetupScrollBar ()
		{
			// When using scroll bar leave the last row of the control free (for over-rendering with scroll bar)
			treeViewFiles.Style.LeaveLastRow = true;

			var scrollBar = new ScrollBarView (treeViewFiles, true);

			scrollBar.ChangedPosition += (s, e) => {
				treeViewFiles.ScrollOffsetVertical = scrollBar.Position;
				if (treeViewFiles.ScrollOffsetVertical != scrollBar.Position) {
					scrollBar.Position = treeViewFiles.ScrollOffsetVertical;
				}
				treeViewFiles.SetNeedsDisplay ();
			};

			scrollBar.OtherScrollBarView.ChangedPosition += (s, e) => {
				treeViewFiles.ScrollOffsetHorizontal = scrollBar.OtherScrollBarView.Position;
				if (treeViewFiles.ScrollOffsetHorizontal != scrollBar.OtherScrollBarView.Position) {
					scrollBar.OtherScrollBarView.Position = treeViewFiles.ScrollOffsetHorizontal;
				}
				treeViewFiles.SetNeedsDisplay ();
			};

			treeViewFiles.DrawContent += (s, e) => {
				scrollBar.Size = treeViewFiles.ContentHeight;
				scrollBar.Position = treeViewFiles.ScrollOffsetVertical;
				scrollBar.OtherScrollBarView.Size = treeViewFiles.GetContentWidth (true);
				scrollBar.OtherScrollBarView.Position = treeViewFiles.ScrollOffsetHorizontal;
				scrollBar.Refresh ();
			};
		}

		private void SetupFileTree ()
		{
			// setup how to build tree
			var fs = new FileSystem ();
			var rootDirs = DriveInfo.GetDrives ().Select (d => fs.DirectoryInfo.New (d.RootDirectory.FullName));
			treeViewFiles.TreeBuilder = new FileSystemTreeBuilder ();
			treeViewFiles.AddObjects (rootDirs);

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

			_iconProvider.IsOpenGetter = treeViewFiles.IsExpanded;
		}

		private string AspectGetter (IFileSystemInfo f)
		{
			return (_iconProvider.GetIconWithOptionalSpace (f) + f.Name).Trim ();
		}

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

			treeViewFiles.Style.ShowBranchLines = (bool)miShowLines.Checked;
			treeViewFiles.SetNeedsDisplay ();
		}

		private void SetExpandableSymbols (Rune expand, Rune? collapse)
		{
			_miPlusMinus.Checked = expand.Value == '+';
			_miArrowSymbols.Checked = expand.Value == '>';
			_miNoSymbols.Checked = expand.Value == default;

			treeViewFiles.Style.ExpandableSymbol = expand;
			treeViewFiles.Style.CollapseableSymbol = collapse;
			treeViewFiles.SetNeedsDisplay ();
		}
		private void ShowColoredExpandableSymbols ()
		{
			_miColoredSymbols.Checked = !_miColoredSymbols.Checked;

			treeViewFiles.Style.ColorExpandSymbol = (bool)_miColoredSymbols.Checked;
			treeViewFiles.SetNeedsDisplay ();
		}
		private void InvertExpandableSymbols ()
		{
			_miInvertSymbols.Checked = !_miInvertSymbols.Checked;

			treeViewFiles.Style.InvertExpandSymbolColors = (bool)_miInvertSymbols.Checked;
			treeViewFiles.SetNeedsDisplay ();
		}

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

			if (_miFullPaths.Checked == true) {
				treeViewFiles.AspectGetter = (f) => f.FullName;
			} else {
				treeViewFiles.AspectGetter = (f) => f.Name;
			}
			treeViewFiles.SetNeedsDisplay ();
		}

		private void SetLeaveLastRow ()
		{
			_miLeaveLastRow.Checked = !_miLeaveLastRow.Checked;
			treeViewFiles.Style.LeaveLastRow = (bool)_miLeaveLastRow.Checked;
		}
		private void SetCursor ()
		{
			_miCursor.Checked = !_miCursor.Checked;
			treeViewFiles.DesiredCursorVisibility = _miCursor.Checked == true ? CursorVisibility.Default : CursorVisibility.Invisible;
		}
		private void SetMultiSelect ()
		{
			_miMultiSelect.Checked = !_miMultiSelect.Checked;
			treeViewFiles.MultiSelect = (bool)_miMultiSelect.Checked;
		}

		private void SetCustomColors ()
		{
			var hidden = new ColorScheme {
				Focus = new Terminal.Gui.Attribute (Color.BrightRed, treeViewFiles.ColorScheme.Focus.Background),
				Normal = new Terminal.Gui.Attribute (Color.BrightYellow, treeViewFiles.ColorScheme.Normal.Background),
			};

			_miCustomColors.Checked = !_miCustomColors.Checked;

			if (_miCustomColors.Checked == true) {
				treeViewFiles.ColorGetter = (m) => {
					if (m is IDirectoryInfo && m.Attributes.HasFlag (FileAttributes.Hidden)) return hidden;
					if (m is IFileInfo && m.Attributes.HasFlag (FileAttributes.Hidden)) return hidden;
					return null;
				};
			} else {
				treeViewFiles.ColorGetter = null;
			}
			treeViewFiles.SetNeedsDisplay ();
		}

		private void SetCheckHighlightModelTextOnly ()
		{
			treeViewFiles.Style.HighlightModelTextOnly = !treeViewFiles.Style.HighlightModelTextOnly;
			_miHighlightModelTextOnly.Checked = treeViewFiles.Style.HighlightModelTextOnly;
			treeViewFiles.SetNeedsDisplay ();
		}

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