using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using Terminal.Gui;
using Attribute = Terminal.Gui.Attribute;

namespace UICatalog.Scenarios {
	[ScenarioMetadata (Name: "Syntax Highlighting", Description: "Text editor with keyword highlighting using the TextView control.")]
	[ScenarioCategory ("Text and Formatting")]
	[ScenarioCategory ("Controls")]
	[ScenarioCategory ("TextView")]
	public class SyntaxHighlighting : Scenario {

		SqlTextView textView;
		MenuItem miWrap;

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

			var menu = new MenuBar (new MenuBarItem [] {
			new MenuBarItem ("_File", new MenuItem [] {
				miWrap =  new MenuItem ("_Word Wrap", "", () => WordWrap()){CheckType = MenuItemCheckStyle.Checked},
				new MenuItem ("_Quit", "", () => Quit()),
			})
			});
			Application.Top.Add (menu);

			textView = new SqlTextView () {
				X = 0,
				Y = 0,
				Width = Dim.Fill (),
				Height = Dim.Fill (1),
			};

			textView.Init ();

			textView.Text = "SELECT TOP 100 * \nfrom\n MyDb.dbo.Biochemistry;";

			Win.Add (textView);

			var statusBar = new StatusBar (new StatusItem [] {
				new StatusItem(Application.QuitKey, $"{Application.QuitKey} to Quit", () => Quit()),
			});


			Application.Top.Add (statusBar);
		}

		private void WordWrap ()
		{
			miWrap.Checked = !miWrap.Checked;
			textView.WordWrap = (bool)miWrap.Checked;
		}

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

		private class SqlTextView : TextView {

			private HashSet<string> keywords = new HashSet<string> (StringComparer.CurrentCultureIgnoreCase);
			private Attribute blue;
			private Attribute white;
			private Attribute magenta;


			public void Init ()
			{
				keywords.Add ("select");
				keywords.Add ("distinct");
				keywords.Add ("top");
				keywords.Add ("from");
				keywords.Add ("create");
				keywords.Add ("CIPHER");
				keywords.Add ("CLASS_ORIGIN");
				keywords.Add ("CLIENT");
				keywords.Add ("CLOSE");
				keywords.Add ("COALESCE");
				keywords.Add ("CODE");
				keywords.Add ("COLUMNS");
				keywords.Add ("COLUMN_FORMAT");
				keywords.Add ("COLUMN_NAME");
				keywords.Add ("COMMENT");
				keywords.Add ("COMMIT");
				keywords.Add ("COMPACT");
				keywords.Add ("COMPLETION");
				keywords.Add ("COMPRESSED");
				keywords.Add ("COMPRESSION");
				keywords.Add ("CONCURRENT");
				keywords.Add ("CONNECT");
				keywords.Add ("CONNECTION");
				keywords.Add ("CONSISTENT");
				keywords.Add ("CONSTRAINT_CATALOG");
				keywords.Add ("CONSTRAINT_SCHEMA");
				keywords.Add ("CONSTRAINT_NAME");
				keywords.Add ("CONTAINS");
				keywords.Add ("CONTEXT");
				keywords.Add ("CONTRIBUTORS");
				keywords.Add ("COPY");
				keywords.Add ("CPU");
				keywords.Add ("CURSOR_NAME");
				keywords.Add ("primary");
				keywords.Add ("key");
				keywords.Add ("insert");
				keywords.Add ("alter");
				keywords.Add ("add");
				keywords.Add ("update");
				keywords.Add ("set");
				keywords.Add ("delete");
				keywords.Add ("truncate");
				keywords.Add ("as");
				keywords.Add ("order");
				keywords.Add ("by");
				keywords.Add ("asc");
				keywords.Add ("desc");
				keywords.Add ("between");
				keywords.Add ("where");
				keywords.Add ("and");
				keywords.Add ("or");
				keywords.Add ("not");
				keywords.Add ("limit");
				keywords.Add ("null");
				keywords.Add ("is");
				keywords.Add ("drop");
				keywords.Add ("database");
				keywords.Add ("table");
				keywords.Add ("having");
				keywords.Add ("in");
				keywords.Add ("join");
				keywords.Add ("on");
				keywords.Add ("union");
				keywords.Add ("exists");

				Autocomplete.SuggestionGenerator = new SingleWordSuggestionGenerator () {
					AllSuggestions = keywords.ToList ()
				};

				magenta = Driver.MakeAttribute (Color.Magenta, Color.Black);
				blue = Driver.MakeAttribute (Color.Cyan, Color.Black);
				white = Driver.MakeAttribute (Color.White, Color.Black);
			}

			protected override void SetNormalColor ()
			{
				Driver.SetAttribute (white);
			}

			protected override void SetNormalColor (List<System.Rune> line, int idx)
			{
				if (IsInStringLiteral (line, idx)) {
					Driver.SetAttribute (magenta);
				} else
				if (IsKeyword (line, idx)) {
					Driver.SetAttribute (blue);
				} else {
					Driver.SetAttribute (white);
				}
			}

			private bool IsInStringLiteral (List<System.Rune> line, int idx)
			{
				string strLine = new string (line.Select (r => (char)r).ToArray ());

				foreach (Match m in Regex.Matches (strLine, "'[^']*'")) {
					if (idx >= m.Index && idx < m.Index + m.Length) {
						return true;
					}
				}

				return false;
			}

			private bool IsKeyword (List<System.Rune> line, int idx)
			{
				var word = IdxToWord (line, idx);

				if (string.IsNullOrWhiteSpace (word)) {
					return false;
				}

				return keywords.Contains (word, StringComparer.CurrentCultureIgnoreCase);
			}

			private string IdxToWord (List<System.Rune> line, int idx)
			{
				var words = Regex.Split (
					new string (line.Select (r => (char)r).ToArray ()),
					"\\b");


				int count = 0;
				string current = null;

				foreach (var word in words) {
					current = word;
					count += word.Length;
					if (count > idx) {
						break;
					}
				}

				return current?.Trim ();
			}
		}
	}
}