Hornet Comm

using System;
using System.Collections.Generic;

namespace _02.HornetComm
{
    class Broadcast
    {
        public string Frequency { get; set; }
        public string Message { get; set; }

        public static string ModifyFrequency(string secondQuery)
        {
            var newQuery = String.Empty;
            for (int index = 0; index < secondQuery.Length; index++)
            {
                var character = secondQuery[index];

                if(character >= 65 && character <= 90)
                {
                    character = (char)(character + 32);
                }
                else if (character >= 97 && character <= 122)
                {
                    character = (char)(character - 32);
                }

                newQuery += character;
            }
            return newQuery;
        }
    }

    class PrivateMessage
    {
        public string Recipient { get; set; }
        public string Message { get; set; }

        public static string ReverseRecipient(string firstQuery)
        {
            var newQuery = String.Empty;
            for (int index = firstQuery.Length - 1; index >= 0; index--)
            {
                newQuery += firstQuery[index];
            }
            return newQuery;
        }
    }

    class HornetComm
    {
        static void Main()
        {
            string input = Console.ReadLine();
            var privateMessages = new List<PrivateMessage>();
            var broadcasts = new List<Broadcast>();

            while (input != "Hornet is Green")
            {
                string[] splitInput = input.Split(new string[] { " <-> "},
                                                  StringSplitOptions.None);

                string firstQuery = string.Empty;
                string secondQuery = string.Empty;

                bool isFirstOnlyDigits = false;
                bool isFirstWithoutDigits = false;
                bool isSecondWithDigisAndLetters = false;

                if (splitInput.Length > 1)
                {
                    firstQuery = splitInput[0];
                    secondQuery = splitInput[1];
                    isFirstOnlyDigits = IsFirstQueryOnlyDigits(firstQuery);
                    isFirstWithoutDigits = IsFirstQueryWithoutDigits(firstQuery);
                    isSecondWithDigisAndLetters = IsSecondQueryWithDigitsAndLetters(secondQuery);
                }

                if(isFirstOnlyDigits && isSecondWithDigisAndLetters)
                {
                    var message = new PrivateMessage()
                    {
                        Recipient = PrivateMessage.ReverseRecipient(firstQuery),
                        Message = secondQuery,
                    };
                    privateMessages.Add(message);
                }
                else if(isFirstWithoutDigits && isSecondWithDigisAndLetters)
                {
                    var broadcast = new Broadcast()
                    {
                        Frequency = Broadcast.ModifyFrequency(secondQuery),
                        Message = firstQuery,
                    };
                    broadcasts.Add(broadcast);
                }

                input = Console.ReadLine();
            }

            PrintBroadcasts(broadcasts);
            PrintPrivateMessages(privateMessages);

        }

        static bool IsFirstQueryOnlyDigits(string firstQuery)
        {
            for (int index = 0; index < firstQuery.Length; index++)
            {
                char currentSymbol = firstQuery[index];

                if (currentSymbol < '0' || currentSymbol > '9')
                {
                    return false;
                }
            }
            return true;
        }

        static bool IsFirstQueryWithoutDigits(string firstQuery)
        {
            for (int index = 0; index < firstQuery.Length; index++)
            {
                char currentSymbol = firstQuery[index];

                if (currentSymbol >= '0' && currentSymbol <= '9')
                {
                    return false;
                }
            }
            return true;
        }

        static bool IsSecondQueryWithDigitsAndLetters(string secondQuery)
        {
            for (int index = 0; index < secondQuery.Length; index++)
            {
                char currentSymbol = secondQuery[index];

                if (currentSymbol < 48 || currentSymbol >= 123 ||
                    (currentSymbol >= 58 && currentSymbol < 65) ||
                    (currentSymbol >= 91 && currentSymbol < 97))
                {
                    return false;
                }
            }
            return true;
        }

        static void PrintBroadcasts(List<Broadcast> broadcasts)
        {
            Console.WriteLine("Broadcasts:");
            if (broadcasts.Count == 0)
            {
                Console.WriteLine("None");
            }
            else
            {
                foreach (var broadcast in broadcasts)
                {
                    string freq = broadcast.Frequency;
                    string message = broadcast.Message;

                    Console.WriteLine("{0} -> {1}", freq, message);
                }
            }
        }

        static void PrintPrivateMessages(List<PrivateMessage> privateMessages)
        {
            Console.WriteLine("Messages:");
            if (privateMessages.Count == 0)
            {
                Console.WriteLine("None");
            }
            else
            {
                foreach (var privateMessage in privateMessages)
                {
                    string recipient = privateMessage.Recipient;
                    string message = privateMessage.Message;

                    Console.WriteLine("{0} -> {1}", recipient, message);
                }
            }
        }
    }
}