PowerToys/src/modules/poweraccent/PowerAccent.Core/Languages.cs

// Copyright (c) Microsoft Corporation
// The Microsoft Corporation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Collections.Concurrent;
using PowerToys.PowerAccentKeyboardService;

namespace PowerAccent.Core
{
    public enum Language
    {
        ALL,
        CA,
        CUR,
        CY,
        CZ,
        GA,
        GD,
        DE,
        EST,
        FR,
        HR,
        HE,
        HU,
        IS,
        IT,
        KU,
        LT,
        MK,
        MI,
        NL,
        NO,
        PI,
        PL,
        PT,
        RO,
        SK,
        SP,
        SR,
        SV,
        TK,
    }

    internal sealed class Languages
    {
        public static string[] GetDefaultLetterKey(LetterKey letter, Language lang)
        {
            return lang switch
            {
                Language.ALL => GetDefaultLetterKeyALL(letter), // ALL
                Language.CA => GetDefaultLetterKeyCA(letter), // Catalan
                Language.CUR => GetDefaultLetterKeyCUR(letter), // Currency
                Language.CY => GetDefaultLetterKeyCY(letter), // Welsh
                Language.CZ => GetDefaultLetterKeyCZ(letter), // Czech
                Language.GA => GetDefaultLetterKeyGA(letter), // Gaeilge (Irish)
                Language.GD => GetDefaultLetterKeyGD(letter), // Gàidhlig (Scottish Gaelic)
                Language.DE => GetDefaultLetterKeyDE(letter), // German
                Language.EST => GetDefaultLetterKeyEST(letter), // Estonian
                Language.FR => GetDefaultLetterKeyFR(letter), // French
                Language.HR => GetDefaultLetterKeyHR(letter), // Croatian
                Language.HE => GetDefaultLetterKeyHE(letter), // Hebrew
                Language.HU => GetDefaultLetterKeyHU(letter), // Hungarian
                Language.IS => GetDefaultLetterKeyIS(letter), // Iceland
                Language.IT => GetDefaultLetterKeyIT(letter), // Italian
                Language.KU => GetDefaultLetterKeyKU(letter), // Kurdish
                Language.LT => GetDefaultLetterKeyLT(letter), // Lithuanian
                Language.MK => GetDefaultLetterKeyMK(letter), // Macedonian
                Language.MI => GetDefaultLetterKeyMI(letter), // Maori
                Language.NL => GetDefaultLetterKeyNL(letter), // Dutch
                Language.NO => GetDefaultLetterKeyNO(letter), // Norwegian
                Language.PI => GetDefaultLetterKeyPI(letter), // Pinyin
                Language.PL => GetDefaultLetterKeyPL(letter), // Polish
                Language.PT => GetDefaultLetterKeyPT(letter), // Portuguese
                Language.RO => GetDefaultLetterKeyRO(letter), // Romanian
                Language.SK => GetDefaultLetterKeySK(letter), // Slovak
                Language.SP => GetDefaultLetterKeySP(letter), // Spain
                Language.SR => GetDefaultLetterKeySR(letter), // Serbian
                Language.SV => GetDefaultLetterKeySV(letter), // Swedish
                Language.TK => GetDefaultLetterKeyTK(letter), // Turkish
                _ => throw new ArgumentException("The language {0} is not know in this context", lang.ToString()),
            };
        }

        // Store the computed letters for each key, so that subsequent calls don't take as long.
        private static ConcurrentDictionary<LetterKey, string[]> _allLanguagesCache = new ConcurrentDictionary<LetterKey, string[]>();

        // All
        private static string[] GetDefaultLetterKeyALL(LetterKey letter)
        {
            if (!_allLanguagesCache.ContainsKey(letter))
            {
                _allLanguagesCache[letter] = GetDefaultLetterKeyCA(letter)
                .Union(GetDefaultLetterKeyCUR(letter))
                .Union(GetDefaultLetterKeyCY(letter))
                .Union(GetDefaultLetterKeyCZ(letter))
                .Union(GetDefaultLetterKeyGA(letter))
                .Union(GetDefaultLetterKeyGD(letter))
                .Union(GetDefaultLetterKeyDE(letter))
                .Union(GetDefaultLetterKeyEST(letter))
                .Union(GetDefaultLetterKeyFR(letter))
                .Union(GetDefaultLetterKeyHR(letter))
                .Union(GetDefaultLetterKeyHE(letter))
                .Union(GetDefaultLetterKeyHU(letter))
                .Union(GetDefaultLetterKeyIS(letter))
                .Union(GetDefaultLetterKeyIT(letter))
                .Union(GetDefaultLetterKeyKU(letter))
                .Union(GetDefaultLetterKeyLT(letter))
                .Union(GetDefaultLetterKeyMK(letter))
                .Union(GetDefaultLetterKeyMI(letter))
                .Union(GetDefaultLetterKeyNL(letter))
                .Union(GetDefaultLetterKeyNO(letter))
                .Union(GetDefaultLetterKeyPI(letter))
                .Union(GetDefaultLetterKeyPL(letter))
                .Union(GetDefaultLetterKeyPT(letter))
                .Union(GetDefaultLetterKeyRO(letter))
                .Union(GetDefaultLetterKeySK(letter))
                .Union(GetDefaultLetterKeySP(letter))
                .Union(GetDefaultLetterKeySR(letter))
                .Union(GetDefaultLetterKeySV(letter))
                .Union(GetDefaultLetterKeyTK(letter))
                .ToArray();
            }

            return _allLanguagesCache[letter];
        }

        // Currencies (source: https://www.eurochange.co.uk/travel-money/world-currency-abbreviations-symbols-and-codes-travel-money)
        private static string[] GetDefaultLetterKeyCUR(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_B => new[] { "฿", "в" },
                LetterKey.VK_C => new[] { "¢", "₡", "č" },
                LetterKey.VK_D => new[] { "₫" },
                LetterKey.VK_E => new[] { "€" },
                LetterKey.VK_F => new[] { "ƒ" },
                LetterKey.VK_H => new[] { "₴" },
                LetterKey.VK_K => new[] { "₭" },
                LetterKey.VK_L => new[] { "ł" },
                LetterKey.VK_N => new[] { "л" },
                LetterKey.VK_M => new[] { "₼" },
                LetterKey.VK_P => new[] { "£", "₽" },
                LetterKey.VK_R => new[] { "₹", "៛", "﷼" },
                LetterKey.VK_S => new[] { "$", "₪" },
                LetterKey.VK_T => new[] { "₮", "₺" },
                LetterKey.VK_W => new[] { "₩" },
                LetterKey.VK_Y => new[] { "¥" },
                LetterKey.VK_Z => new[] { "z" },
                _ => Array.Empty<string>(),
            };
        }

        // Croatian
        private static string[] GetDefaultLetterKeyHR(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_C => new[] { "ć", "č" },
                LetterKey.VK_D => new[] { "đ" },
                LetterKey.VK_S => new[] { "š" },
                LetterKey.VK_Z => new[] { "ž" },
                _ => Array.Empty<string>(),
            };
        }

        // Estonian
        private static string[] GetDefaultLetterKeyEST(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "ä" },
                LetterKey.VK_E => new[] { "€" },
                LetterKey.VK_O => new[] { "ö", "õ" },
                LetterKey.VK_U => new[] { "ü" },
                LetterKey.VK_Z => new[] { "ž" },
                LetterKey.VK_S => new[] { "š" },
                _ => Array.Empty<string>(),
            };
        }

        // French
        private static string[] GetDefaultLetterKeyFR(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "à", "â", "á", "ä", "ã", "æ" },
                LetterKey.VK_C => new[] { "ç" },
                LetterKey.VK_E => new[] { "é", "è", "ê", "ë", "€" },
                LetterKey.VK_I => new[] { "î", "ï", "í", "ì" },
                LetterKey.VK_O => new[] { "ô", "ö", "ó", "ò", "õ", "œ" },
                LetterKey.VK_U => new[] { "û", "ù", "ü", "ú" },
                LetterKey.VK_Y => new[] { "ÿ", "ý" },
                _ => Array.Empty<string>(),
            };
        }

        // Iceland
        private static string[] GetDefaultLetterKeyIS(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "á", "æ" },
                LetterKey.VK_D => new[] { "ð" },
                LetterKey.VK_E => new[] { "é" },
                LetterKey.VK_O => new[] { "ó", "ö" },
                LetterKey.VK_U => new[] { "ú" },
                LetterKey.VK_Y => new[] { "ý" },
                LetterKey.VK_T => new[] { "þ" },
                _ => Array.Empty<string>(),
            };
        }

        // Spain
        private static string[] GetDefaultLetterKeySP(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "á" },
                LetterKey.VK_E => new[] { "é", "€" },
                LetterKey.VK_I => new[] { "í" },
                LetterKey.VK_N => new[] { "ñ" },
                LetterKey.VK_O => new[] { "ó" },
                LetterKey.VK_U => new[] { "ú", "ü" },
                LetterKey.VK_COMMA => new[] { "¿", "?", "¡", "!" },
                _ => Array.Empty<string>(),
            };
        }

        // Catalan
        private static string[] GetDefaultLetterKeyCA(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "à", "á" },
                LetterKey.VK_C => new[] { "ç" },
                LetterKey.VK_E => new[] { "è", "é", "€" },
                LetterKey.VK_I => new[] { "ì", "í", "ï" },
                LetterKey.VK_N => new[] { "ñ" },
                LetterKey.VK_O => new[] { "ò", "ó" },
                LetterKey.VK_U => new[] { "ù", "ú", "ü" },
                LetterKey.VK_L => new[] { "·" },
                LetterKey.VK_COMMA => new[] { "¿", "?", "¡", "!" },
                _ => Array.Empty<string>(),
            };
        }

        // Maori
        private static string[] GetDefaultLetterKeyMI(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "ā" },
                LetterKey.VK_E => new[] { "ē" },
                LetterKey.VK_I => new[] { "ī" },
                LetterKey.VK_O => new[] { "ō" },
                LetterKey.VK_S => new[] { "$" },
                LetterKey.VK_U => new[] { "ū" },
                _ => Array.Empty<string>(),
            };
        }

        // Dutch
        private static string[] GetDefaultLetterKeyNL(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "á", "à", "ä" },
                LetterKey.VK_C => new[] { "ç" },
                LetterKey.VK_E => new[] { "é", "è", "ë", "ê", "€" },
                LetterKey.VK_I => new[] { "í", "ï", "î" },
                LetterKey.VK_N => new[] { "ñ" },
                LetterKey.VK_O => new[] { "ó", "ö", "ô" },
                LetterKey.VK_U => new[] { "ú", "ü", "û" },
                _ => Array.Empty<string>(),
            };
        }

        // Pinyin
        private static string[] GetDefaultLetterKeyPI(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_1 => new[] { "\u0304", "ˉ" },
                LetterKey.VK_2 => new[] { "\u0301", "ˊ" },
                LetterKey.VK_3 => new[] { "\u030c", "ˇ" },
                LetterKey.VK_4 => new[] { "\u0300", "ˋ" },
                LetterKey.VK_5 => new[] { "·" },
                LetterKey.VK_A => new[] { "ā", "á", "ǎ", "à", "ɑ", "ɑ\u0304", "ɑ\u0301", "ɑ\u030c", "ɑ\u0300" },
                LetterKey.VK_C => new[] { "ĉ" },
                LetterKey.VK_E => new[] { "ē", "é", "ě", "è", "ê", "ê\u0304", "ế", "ê\u030c", "ề" },
                LetterKey.VK_I => new[] { "ī", "í", "ǐ", "ì" },
                LetterKey.VK_M => new[] { "m\u0304", "ḿ", "m\u030c", "m\u0300" },
                LetterKey.VK_N => new[] { "n\u0304", "ń", "ň", "ǹ", "ŋ", "ŋ\u0304", "ŋ\u0301", "ŋ\u030c", "ŋ\u0300" },
                LetterKey.VK_O => new[] { "ō", "ó", "ǒ", "ò" },
                LetterKey.VK_S => new[] { "ŝ" },
                LetterKey.VK_U => new[] { "ū", "ú", "ǔ", "ù", "ü", "ǖ", "ǘ", "ǚ", "ǜ" },
                LetterKey.VK_V => new[] { "ü", "ǖ", "ǘ", "ǚ", "ǜ" },
                LetterKey.VK_Y => new[] { "¥" },
                LetterKey.VK_Z => new[] { "ẑ" },
                _ => Array.Empty<string>(),
            };
        }

        // Turkish
        private static string[] GetDefaultLetterKeyTK(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "â" },
                LetterKey.VK_C => new[] { "ç" },
                LetterKey.VK_E => new[] { "ë", "€" },
                LetterKey.VK_G => new[] { "ğ" },
                LetterKey.VK_I => new[] { "ı", "İ", "î", },
                LetterKey.VK_O => new[] { "ö", "ô" },
                LetterKey.VK_S => new[] { "ş" },
                LetterKey.VK_T => new[] { "₺" },
                LetterKey.VK_U => new[] { "ü", "û" },
                _ => Array.Empty<string>(),
            };
        }

        // Polish
        private static string[] GetDefaultLetterKeyPL(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "ą" },
                LetterKey.VK_C => new[] { "ć" },
                LetterKey.VK_E => new[] { "ę", "€" },
                LetterKey.VK_L => new[] { "ł" },
                LetterKey.VK_N => new[] { "ń" },
                LetterKey.VK_O => new[] { "ó" },
                LetterKey.VK_S => new[] { "ś" },
                LetterKey.VK_Z => new[] { "ż", "ź" },
                _ => Array.Empty<string>(),
            };
        }

        // Portuguese
        private static string[] GetDefaultLetterKeyPT(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_0 => new[] { "₀", "⁰" },
                LetterKey.VK_1 => new[] { "₁", "¹" },
                LetterKey.VK_2 => new[] { "₂", "²" },
                LetterKey.VK_3 => new[] { "₃", "³" },
                LetterKey.VK_4 => new[] { "₄", "⁴" },
                LetterKey.VK_5 => new[] { "₅", "⁵" },
                LetterKey.VK_6 => new[] { "₆", "⁶" },
                LetterKey.VK_7 => new[] { "₇", "⁷" },
                LetterKey.VK_8 => new[] { "₈", "⁸" },
                LetterKey.VK_9 => new[] { "₉", "⁹" },
                LetterKey.VK_A => new[] { "á", "à", "â", "ã" },
                LetterKey.VK_C => new[] { "ç" },
                LetterKey.VK_E => new[] { "é", "ê", "€" },
                LetterKey.VK_I => new[] { "í" },
                LetterKey.VK_O => new[] { "ô", "ó", "õ" },
                LetterKey.VK_P => new[] { "π" },
                LetterKey.VK_S => new[] { "$" },
                LetterKey.VK_U => new[] { "ú" },
                LetterKey.VK_COMMA => new[] { "≤", "≥", "≠", "≈", "≙", "±", "₊", "⁺" },
                _ => Array.Empty<string>(),
            };
        }

        // Slovak
        private static string[] GetDefaultLetterKeySK(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "á", "ä" },
                LetterKey.VK_C => new[] { "č" },
                LetterKey.VK_D => new[] { "ď" },
                LetterKey.VK_E => new[] { "é", "€" },
                LetterKey.VK_I => new[] { "í" },
                LetterKey.VK_L => new[] { "ľ", "ĺ" },
                LetterKey.VK_N => new[] { "ň" },
                LetterKey.VK_O => new[] { "ó", "ô" },
                LetterKey.VK_R => new[] { "ŕ" },
                LetterKey.VK_S => new[] { "š" },
                LetterKey.VK_T => new[] { "ť" },
                LetterKey.VK_U => new[] { "ú" },
                LetterKey.VK_Y => new[] { "ý" },
                LetterKey.VK_Z => new[] { "ž" },
                _ => Array.Empty<string>(),
            };
        }

        // Gaeilge (Irish language)
        private static string[] GetDefaultLetterKeyGA(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "á" },
                LetterKey.VK_E => new[] { "é" },
                LetterKey.VK_I => new[] { "í" },
                LetterKey.VK_O => new[] { "ó" },
                LetterKey.VK_U => new[] { "ú" },
                _ => Array.Empty<string>(),
            };
        }

        // Gàidhlig (Scottish Gaelic)
        private static string[] GetDefaultLetterKeyGD(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "à" },
                LetterKey.VK_E => new[] { "è" },
                LetterKey.VK_I => new[] { "ì" },
                LetterKey.VK_O => new[] { "ò" },
                LetterKey.VK_U => new[] { "ù" },
                _ => Array.Empty<string>(),
            };
        }

        // Czech
        private static string[] GetDefaultLetterKeyCZ(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "á" },
                LetterKey.VK_C => new[] { "č" },
                LetterKey.VK_D => new[] { "ď" },
                LetterKey.VK_E => new[] { "ě", "é" },
                LetterKey.VK_I => new[] { "í" },
                LetterKey.VK_N => new[] { "ň" },
                LetterKey.VK_O => new[] { "ó" },
                LetterKey.VK_R => new[] { "ř" },
                LetterKey.VK_S => new[] { "š" },
                LetterKey.VK_T => new[] { "ť" },
                LetterKey.VK_U => new[] { "ů", "ú" },
                LetterKey.VK_Y => new[] { "ý" },
                LetterKey.VK_Z => new[] { "ž" },
                _ => Array.Empty<string>(),
            };
        }

        // German
        private static string[] GetDefaultLetterKeyDE(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "ä" },
                LetterKey.VK_E => new[] { "€" },
                LetterKey.VK_O => new[] { "ö" },
                LetterKey.VK_S => new[] { "ß" },
                LetterKey.VK_U => new[] { "ü" },
                _ => Array.Empty<string>(),
            };
        }

        // Hebrew
        private static string[] GetDefaultLetterKeyHE(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "שׂ", "שׁ", "\u05b0" },
                LetterKey.VK_B => new[] { "׆" },
                LetterKey.VK_E => new[] { "\u05b8", "\u05b3", "\u05bb" },
                LetterKey.VK_G => new[] { "ױ" },
                LetterKey.VK_H => new[] { "ײ", "ײַ", "ׯ", "\u05b4" },
                LetterKey.VK_M => new[] { "\u05b5" },
                LetterKey.VK_P => new[] { "\u05b7", "\u05b2" },
                LetterKey.VK_S => new[] { "\u05bc" },
                LetterKey.VK_T => new[] { "ﭏ" },
                LetterKey.VK_U => new[] { "וֹ", "וּ", "װ", "\u05b9" },
                LetterKey.VK_X => new[] { "\u05b6", "\u05b1" },
                LetterKey.VK_Y => new[] { "ױ" },
                LetterKey.VK_COMMA => new[] { "”", "’", "״", "׳" },
                LetterKey.VK_PERIOD => new[] { "\u05ab", "\u05bd", "\u05bf" },
                LetterKey.VK_MINUS => new[] { "–", "־" },
                _ => Array.Empty<string>(),
            };
        }

        // Hungarian
        private static string[] GetDefaultLetterKeyHU(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "á" },
                LetterKey.VK_E => new[] { "é" },
                LetterKey.VK_I => new[] { "í" },
                LetterKey.VK_O => new[] { "ó", "ő", "ö" },
                LetterKey.VK_U => new[] { "ú", "ű", "ü" },
                _ => Array.Empty<string>(),
            };
        }

        // Romanian
        private static string[] GetDefaultLetterKeyRO(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "ă", "â" },
                LetterKey.VK_I => new[] { "î" },
                LetterKey.VK_S => new[] { "ș" },
                LetterKey.VK_T => new[] { "ț" },
                _ => Array.Empty<string>(),
            };
        }

        // Italian
        private static string[] GetDefaultLetterKeyIT(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "à" },
                LetterKey.VK_E => new[] { "è", "é", "€" },
                LetterKey.VK_I => new[] { "ì", "í" },
                LetterKey.VK_O => new[] { "ò", "ó" },
                LetterKey.VK_U => new[] { "ù", "ú" },
                _ => Array.Empty<string>(),
            };
        }

        // Kurdish
        private static string[] GetDefaultLetterKeyKU(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_C => new[] { "ç" },
                LetterKey.VK_E => new[] { "ê", "€" },
                LetterKey.VK_I => new[] { "î" },
                LetterKey.VK_O => new[] { "ö", "ô" },
                LetterKey.VK_L => new[] { "ł" },
                LetterKey.VK_N => new[] { "ň" },
                LetterKey.VK_R => new[] { "ř" },
                LetterKey.VK_S => new[] { "ş" },
                LetterKey.VK_U => new[] { "û", "ü" },
                _ => Array.Empty<string>(),
            };
        }

        // Welsh
        private static string[] GetDefaultLetterKeyCY(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "â" },
                LetterKey.VK_E => new[] { "ê" },
                LetterKey.VK_I => new[] { "î" },
                LetterKey.VK_O => new[] { "ô" },
                LetterKey.VK_U => new[] { "û" },
                LetterKey.VK_Y => new[] { "ŷ" },
                LetterKey.VK_W => new[] { "ŵ" },
                _ => Array.Empty<string>(),
            };
        }

        // Swedish
        private static string[] GetDefaultLetterKeySV(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "å", "ä" },
                LetterKey.VK_E => new[] { "é" },
                LetterKey.VK_O => new[] { "ö" },
                _ => Array.Empty<string>(),
            };
        }

        // Serbian
        private static string[] GetDefaultLetterKeySR(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_C => new[] { "ć", "č" },
                LetterKey.VK_D => new[] { "đ" },
                LetterKey.VK_S => new[] { "š" },
                LetterKey.VK_Z => new[] { "ž" },
                _ => Array.Empty<string>(),
            };
        }

        // Macedonian
        private static string[] GetDefaultLetterKeyMK(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_E => new[] { "ѐ" },
                LetterKey.VK_I => new[] { "ѝ" },
                _ => Array.Empty<string>(),
            };
        }

        // Norwegian
        private static string[] GetDefaultLetterKeyNO(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "å", "æ" },
                LetterKey.VK_E => new[] { "€", "é" },
                LetterKey.VK_O => new[] { "ø" },
                LetterKey.VK_S => new[] { "$" },
                _ => Array.Empty<string>(),
            };
        }

        // Lithuanian
        private static string[] GetDefaultLetterKeyLT(LetterKey letter)
        {
            return letter switch
            {
                LetterKey.VK_A => new[] { "ą" },
                LetterKey.VK_C => new[] { "č" },
                LetterKey.VK_E => new[] { "ę", "ė", "€" },
                LetterKey.VK_I => new[] { "į" },
                LetterKey.VK_S => new[] { "š" },
                LetterKey.VK_U => new[] { "ų", "ū" },
                LetterKey.VK_Z => new[] { "ž" },
                _ => Array.Empty<string>(),
            };
        }
    }
}