// Skeleton Program for the AQA AS Summer 2018 examination
// this code should be used in conjunction with the Preliminary Material
// written by the AQA AS Programmer Team
// developed using Visual Studio Community Edition

// Version Number : 0.2

using System.IO;
using System;
using Microsoft.VisualBasic; // Install-Package Microsoft.VisualBasic
using Microsoft.VisualBasic.CompilerServices; // Install-Package Microsoft.VisualBasic

internal static partial class Module1
{
    private const char SPACE = ' ';
    private const char EOL = '#';
    private const string EMPTYSTRING = "";

    public static void ReportError(string s)
    {
        Console.WriteLine("*".PadRight(6) + s + "*".PadLeft(6));
    }

    public static string StripLeadingSpaces(string Transmission)
    {
        int TransmissionLength = Transmission.Length;
        char FirstSignal;
        if (TransmissionLength > 0)
        {
            FirstSignal = Transmission[0];
            while (FirstSignal == SPACE & TransmissionLength > 0)
            {
                TransmissionLength -= 1;
                Transmission = Transmission.Substring(1);
                if (TransmissionLength > 0)
                {
                    FirstSignal = Transmission[0];
                }
            }
        }

        if (TransmissionLength == 0)
        {
            ReportError("No signal received");
        }

        return Transmission;
    }

    public static string StripTrailingSpaces(string Transmission)
    {
        int LastChar = Transmission.Length - 1;
        while (Transmission[LastChar] == SPACE)
        {
            Transmission = Transmission.Remove(LastChar);
            LastChar -= 1;
        }

        return Transmission;
    }

    public static string GetTransmission()
    {
        string Filename;
        string Transmission;
        Console.Write("Enter file name: ");
        try
        {
            Filename = Console.ReadLine();
            var Reader = new StreamReader(Filename);
            Transmission = Reader.ReadLine();
            Reader.Close();
            Transmission = StripLeadingSpaces(Transmission);
            if (Transmission.Length > 0)
            {
                Transmission = StripTrailingSpaces(Transmission);
                Transmission = Transmission + Conversions.ToString(EOL);
            }
        }
        catch
        {
            ReportError("No transmission found");
            Transmission = EMPTYSTRING;
        }

        return Transmission;
    }

    public static string GetNextSymbol(ref int i, string Transmission)
    {
        string Signal;
        int SymbolLength;
        char Symbol;
        if (Transmission[i] == EOL)
        {
            Console.WriteLine();
            Console.WriteLine("End of transmission");
            Symbol = Conversions.ToChar(EMPTYSTRING);
        }
        else
        {
            SymbolLength = 0;
            Signal = Conversions.ToString(Transmission[i]);
            while (Signal != Conversions.ToString(SPACE) & Signal != Conversions.ToString(EOL))
            {
                i += 1;
                Signal = Conversions.ToString(Transmission[i]);
                SymbolLength += 1;
            }

            if (SymbolLength == 1)
            {
                Symbol = '.';
            }
            else if (SymbolLength == 3)
            {
                Symbol = '-';
            }
            else if (SymbolLength == 0)
            {
                Symbol = SPACE;
            }
            else
            {
                ReportError("Non-standard symbol received");
                Symbol = Conversions.ToChar(EMPTYSTRING);
            }
        }

        return Conversions.ToString(Symbol);
    }

    public static string GetNextLetter(ref int i, string Transmission)
    {
        string SymbolString = EMPTYSTRING;
        bool LetterEnd = false;
        string Symbol;
        while (!LetterEnd)
        {
            Symbol = GetNextSymbol(ref i, Transmission);
            if (Symbol == Conversions.ToString(SPACE))
            {
                LetterEnd = true;
                i += 4;
            }
            else if (Transmission[i] == EOL)
            {
                LetterEnd = true;
            }
            else if (Transmission[i + 1] == SPACE & Transmission[i + 2] == SPACE)
            {
                LetterEnd = true;
                i += 3;
            }
            else
            {
                i += 1;
            }

            SymbolString = SymbolString + Symbol;
        }

        return SymbolString;
    }

    public static string Decode(string CodedLetter, int[] Dash, string[] Letter, int[] Dot)
    {
        int CodedLetterLength = CodedLetter.Length;
        int Pointer = 0;
        char Symbol;
        for (int i = 0, loopTo = CodedLetterLength - 1; i <= loopTo; i++)
        {
            Symbol = CodedLetter[i];
            if (Symbol == SPACE)
            {
                return Conversions.ToString(SPACE);
            }
            else if (Conversions.ToString(Symbol) == "-")
            {
                Pointer = Dash[Pointer];
            }
            else
            {
                Pointer = Dot[Pointer];
            }
        }

        return Letter[Pointer];
    }

    public static void ReceiveMorseCode(int[] Dash, string[] Letter, int[] Dot)
    {
        string PlainText = EMPTYSTRING;
        string MorseCodeString = EMPTYSTRING;
        string Transmission = GetTransmission();
        int LastChar = Transmission.Length - 1;
        int i = 0;
        string CodedLetter;
        char PlainTextLetter;
        while (i < LastChar)
        {
            CodedLetter = GetNextLetter(ref i, Transmission);
            MorseCodeString = MorseCodeString + Conversions.ToString(SPACE) + CodedLetter;
            PlainTextLetter = Conversions.ToChar(Decode(CodedLetter, Dash, Letter, Dot));
            PlainText = PlainText + Conversions.ToString(PlainTextLetter);
        }

        Console.WriteLine(MorseCodeString);
        Console.WriteLine(PlainText);
    }

    public static void SendMorseCode(string[] MorseCode)
    {
        string PlainText;
        int PlainTextLength;
        string MorseCodeString;
        char PlainTextLetter;
        string CodedLetter;
        int Index;
        Console.Write("Enter your message (uppercase letters and spaces only): ");
        PlainText = Console.ReadLine();
        PlainTextLength = PlainText.Length;
        MorseCodeString = EMPTYSTRING;
        for (int i = 0, loopTo = PlainTextLength - 1; i <= loopTo; i++)
        {
            PlainTextLetter = PlainText[i];
            if (PlainTextLetter == SPACE)
            {
                Index = 0;
            }
            else
            {
                Index = Strings.Asc(PlainTextLetter) - Strings.Asc("A") + 1;
            }

            CodedLetter = MorseCode[Index];
            MorseCodeString = MorseCodeString + CodedLetter + Conversions.ToString(SPACE);
        }

        Console.WriteLine(MorseCodeString);
    }

    public static void DisplayMenu()
    {
        Console.WriteLine();
        Console.WriteLine("Main Menu");
        Console.WriteLine("=========");
        Console.WriteLine("R - Receive Morse code");
        Console.WriteLine("S - Send Morse code");
        Console.WriteLine("X - Exit program");
        Console.WriteLine();
    }

    public static string GetMenuOption()
    {
        string MenuOption = EMPTYSTRING;
        while (MenuOption.Length != 1)
        {
            Console.Write("Enter your choice: ");
            MenuOption = Console.ReadLine();
        }

        return MenuOption;
    }

    public static void SendReceiveMessages()
    {
        var Dash = new[] { 20, 23, 0, 0, 24, 1, 0, 17, 0, 21, 0, 25, 0, 15, 11, 0, 0, 0, 0, 22, 13, 0, 0, 10, 0, 0, 0 };
        var Letter = new[] { " ", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };
        var Dot = new[] { 5, 18, 0, 0, 2, 9, 0, 26, 0, 19, 0, 3, 0, 7, 4, 0, 0, 0, 12, 8, 14, 6, 0, 16, 0, 0, 0 };
        var MorseCode = new[] { " ", ".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--.." };
        string MenuOption;
        bool ProgramEnd = false;
        while (!ProgramEnd)
        {
            DisplayMenu();
            MenuOption = GetMenuOption();
            if (MenuOption == "R")
            {
                ReceiveMorseCode(Dash, Letter, Dot);
            }
            else if (MenuOption == "S")
            {
                SendMorseCode(MorseCode);
            }
            else if (MenuOption == "X")
            {
                ProgramEnd = true;
            }
        }
    }

    public static void Main()
    {
        SendReceiveMessages();
        Console.ReadLine();
    }
}