Symbolic Coordinates Twitch play code

        public KMSelectable[] ProcessTwitchCommand(string command)
        {
            string[] split = command.ToUpperInvariant().Split(new[] {' '}, StringSplitOptions.RemoveEmptyEntries);

            if (split.Length < 2)
                return null;

            switch (split[0])
            {
                case "SUBMIT":
                    string letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ*";
                    string digits = "0123456789*";
                    if (split[1].Length < 2 || !letters.Contains(split[1].Substring(0, 1)) || !digits.Contains(split[1].Substring(1, 1)))
                        return null;
                    int desiredLetter = letters.IndexOf(split[1].Substring(0, 1), StringComparison.Ordinal);
                    int desiredDigit = digits.IndexOf(split[1].Substring(1, 1), StringComparison.Ordinal);
                    int currentLetter = letters.IndexOf(lettersText.text, StringComparison.Ordinal);
                    int currentDigit = digits.IndexOf(digitsText.text, StringComparison.Ordinal);
                    List <KMSelectable> list = new List<KMSelectable>();
                    for(int i = currentLetter; i != desiredLetter; i = ((i + 1) % letters.Length))
                        list.Add(lettersDown);
                    for(int i = currentDigit; i != desiredDigit; i = ((i + 1) % digits.Length))
                        list.Add(digitsDown);
                    list.Add(submitBut);
                    return list.ToArray();
                    break;
                case "PRESS":
                    switch (split[1])
                    {
                        case "LETTER":
                            if (split.Length < 3) return null;
                            if(split[2] == "UP")
                                return new KMSelectable[] { lettersDown };
                            if(split[2] == "DOWN")
                                return new KMSelectable[] { lettersUp };
                            return null;
                        case "DIGIT":
                            if (split.Length < 3) return null;
                            if (split[2] == "UP")
                                return new KMSelectable[] { digitsDown };
                            if (split[2] == "DOWN")
                                return new KMSelectable[] { digitsUp };
                            return null;
                            break;
                        case "SUBMIT":
                            return new KMSelectable[] { submitBut };
                        default:
                            return null;
                    }
                default:
                    return null;
            }
        }