using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using Rune = System.Rune;

namespace Terminal.Gui {

	public abstract class AutocompleteBase : IAutocomplete {
		
		/// <inheritdoc/>
		public abstract View HostControl { get; set; }
		/// <inheritdoc/>
		public bool PopupInsideContainer { get; set; }
		
		public ISuggestionGenerator SuggestionGenerator {get;set;} = new SingleWordSuggestionGenerator();

		/// <inheritdoc/>
		public virtual int MaxWidth { get; set; } = 10;

		/// <inheritdoc/>
		public virtual int MaxHeight { get; set; } = 6;

		/// <inheritdoc/>


		/// <inheritdoc/>
		public virtual bool Visible { get; set; }

		/// <inheritdoc/>
		public virtual ReadOnlyCollection<Suggestion> Suggestions { get; set; } = new ReadOnlyCollection<Suggestion> (new Suggestion [0]);



		/// <inheritdoc/>
		public virtual int SelectedIdx { get; set; }


		/// <inheritdoc/>
		public abstract ColorScheme ColorScheme { get; set; }

		/// <inheritdoc/>
		public virtual Key SelectionKey { get; set; } = Key.Enter;

		/// <inheritdoc/>
		public virtual Key CloseKey { get; set; } = Key.Esc;

		/// <inheritdoc/>
		public virtual Key Reopen { get; set; } = Key.Space | Key.CtrlMask | Key.AltMask;

		/// <inheritdoc/>
		public abstract bool MouseEvent (MouseEvent me, bool fromHost = false);

		/// <inheritdoc/>
		public abstract bool ProcessKey (KeyEvent kb);
		/// <inheritdoc/>
		public abstract void RenderOverlay (Point renderAt);

		/// <inheritdoc/>>
		public virtual void ClearSuggestions ()
		{
			Suggestions = Enumerable.Empty<Suggestion> ().ToList ().AsReadOnly ();
		}


		/// <inheritdoc/>
		public virtual void GenerateSuggestions (List<Rune> currentLine, int idx)
		{
			Suggestions = SuggestionGenerator.GenerateSuggestions(currentLine, idx).ToList().AsReadOnly();

			EnsureSelectedIdxIsValid ();
		}

		/// <summary>
		/// Updates <see cref="SelectedIdx"/> to be a valid index within <see cref="Suggestions"/>
		/// </summary>
		public virtual void EnsureSelectedIdxIsValid ()
		{
			SelectedIdx = Math.Max (0, Math.Min (Suggestions.Count - 1, SelectedIdx));
		}
	}
}