using System;

using System.Collections.Generic;

using System.ComponentModel.Composition;

using System.Linq;

using System.Text;



namespace Vim.UI.Wpf.Implementation.CharDisplay

{

    [Export(typeof(IControlCharUtil))]

    internal sealed class ControlCharUtil : IControlCharUtil

    {

        private bool _displayControlChars = true;

        private EventHandler _displayControlCharsChanged;



        private bool DisplayControlChars

        {

            get { return _displayControlChars; }

            set

            {

                if (value != _displayControlChars)

                {

                    _displayControlChars = value;

                    RaiseDisplayControlCharsChanged();

                }

            }

        }



        internal static bool IsDisplayControlChar(char c)

        {

            var i = (int)c;

            return IsRelevant(i);

        }



        internal static bool IsRelevant(int i)

        {

            return i <= 31;

        }



        internal static bool TryGetDisplayText(char c, out string text)

        {

            var i = (int)c;

            if (!IsRelevant(i))

            {

                text = null;

                return false;

            }



            // There is an intentional gap here from 9 - 13 inclusive.  These represent characters like tab, newline,

            // etc ...  which shouldn't be special cased in display by VsVim

            if (i >= 9 && i <= 13)

            {

                text = null;

                return false;

            }



            return TryGetDisplayText(i, out text);

        }



        internal static bool TryGetDisplayText(int i, out string text)

        {

            text = null;

            switch (i)

            {

                case 0: text = "^@"; break;

                case 1: text = "^A"; break;

                case 2: text = "^B"; break;

                case 3: text = "^C"; break;

                case 4: text = "^D"; break;

                case 5: text = "^E"; break;

                case 6: text = "^F"; break;

                case 7: text = "^G"; break;

                case 8: text = "^H"; break;

                case 9: text = "^I"; break;

                case 10: text = "^J"; break;

                case 11: text = "^K"; break;

                case 12: text = "^L"; break;

                case 13: text = "^M"; break;

                case 14: text = "^N"; break;

                case 15: text = "^O"; break;

                case 16: text = "^P"; break;

                case 17: text = "^Q"; break;

                case 18: text = "^R"; break;

                case 19: text = "^S"; break;

                case 20: text = "^T"; break;

                case 21: text = "^U"; break;

                case 22: text = "^V"; break;

                case 23: text = "^W"; break;

                case 24: text = "^X"; break;

                case 25: text = "^Y"; break;

                case 26: text = "^Z"; break;

                case 27: text = "^["; break;

                case 28: text = "^\\"; break;

                case 29: text = "^]"; break;

                case 30: text = "^^"; break;

                case 31: text = "^_"; break;

            }



            return text != null;

        }



        private void RaiseDisplayControlCharsChanged()

        {

            _displayControlCharsChanged?.Invoke(this, EventArgs.Empty);

        }



        #region IControlCharUtil



        bool IControlCharUtil.DisplayControlChars

        {

            get { return DisplayControlChars; }

            set { DisplayControlChars = value; }

        }



        event EventHandler IControlCharUtil.DisplayControlCharsChanged

        {

            add { _displayControlCharsChanged += value; }

            remove { _displayControlCharsChanged -= value; }

        }



        bool IControlCharUtil.IsDisplayControlChar(char c)

        {

            return IsDisplayControlChar(c);

        }



        bool IControlCharUtil.TryGetDisplayText(char c, out string text)

        {

            return TryGetDisplayText(c, out text);

        }



        #endregion

    }

}