#include <iostream>
#include <string>
#include <sstream>
#include<unistd.h>
using namespace std;

#define POLY 0x1021
string t;
int a,e,c;
unsigned short EncodeCRT(char *ptr, int count)
{
   int  crc;
   char i;
   crc = 0xffff;
   while (--count >= 0)
   {
      crc = crc ^ (int) *ptr++ << 8;
      i = 8;
      do
      {
         if (crc & 0x8000)
            crc = crc << 1 ^ 0x1021;
         else
            crc = crc << 1;
      } while(--i);
   }
   return (crc);
}

string CheckCrc(string message)
{
    string crc="1000000100001";
    for(int i=0;i<=message.length()-crc.length();)
    {
          for(int j=0;j<crc.length();j++)
            message[i+j]=message[i+j]==crc[j]? '0' : '1';
          for( ; i<message.length() && message[i]!='1';i++);
    }
    for(char i: message.substr(message.length()-crc.length()))
      if(i!='0')
      {
            return "FALSE";
      }
    return "TRUE";
}
const char* hex_char_to_bin(char c)
{
    // TODO handle default / error
    switch(toupper(c))
    {
        case '0': return "0000";
        case '1': return "0001";
        case '2': return "0010";
        case '3': return "0011";
        case '4': return "0100";
        case '5': return "0101";
        case '6': return "0110";
        case '7': return "0111";
        case '8': return "1000";
        case '9': return "1001";
        case 'A': return "1010";
        case 'B': return "1011";
        case 'C': return "1100";
        case 'D': return "1101";
        case 'E': return "1110";
        case 'F': return "1111";
    }
}

std::string hexToBin(string &hex)
{
    // TODO use a loop from <algorithm> or smth
    std::string bin;
    for(unsigned i = 0; i != hex.length(); ++i)
       bin += hex_char_to_bin(hex[i]);
    return bin;
}
void two(string &in)
{
      
}
int main()
{
            char* input;
            cout<<("1. Zakoduj wiadomosc");
                cout<<("2. Odkoduj wiadomosc");
                cout<<("3. Wyjscie");
                int choice=0;
                cin>>choice;
                cin.ignore();
                if(choice==1)
                {
                    int cc=0;
                    cout<<("Podaj dlugosc wiadomosci.(ilosc liter ze spacjami wlacznie)");
                    cin>>cc;
                    input=new char[cc];
                    cout<<("Podaj wiadomosc do zaszyfrowania.");
                    cin.ignore();
                    cin.getline(input,cc+1);
                    unsigned short result =EncodeCRT(input,cc);
                    
                    for(int i=0;i<cc;i++){
                        printf("%x",input[i]);
                        printf(" ");
                    }
                    printf("%x",result);
                    printf("  ");
                    
                }
                    if(choice==2)
                    {

                         string input3;
                         cout<<"Podaj wiadomosc do odkodowania w systemie szesnastkowym, bez spacji.";
                         cin>>input3;
                          string xd;
                          std::stringstream ss;
                        std::string bin;
                        string hex=input3;

    for(unsigned i = 0; i != hex.length(); ++i)
       {
       switch(toupper(hex[i]))
    {
        case '0': bin+= "0000"; break;
        case '1': bin+= "0001"; break;
        case '2': bin+= "0010"; break;
        case '3': bin+= "0011"; break;
        case '4': bin+= "0100";break;
        case '5': bin+= "0101";break;
        case '6': bin+= "0110";break;
        case '7': bin+= "0111";break;
        case '8': bin+= "1000";break;
        case '9': bin+= "1001";break;
        case 'A': bin+= "1010";break;
        case 'B': bin+= "1011";break;
        case 'C': bin+= "1100";break;
        case 'D': bin+= "1101";break;
        case 'E': bin+= "1110";break;
        case 'F': bin+= "1111";break;
    }
       }
       
       string crc="1000000100001";
       string message=bin;
       int l=message.length();
       int cl=crc.length();
       int ii=0;
       int k=0;
      l=message.length();
    while(true)
    {
          if(ii>l-cl) break;
         for(int j=0;j<cl;j++)
          {  
             message[ii+j]=message[ii+j]==crc[j]? '0' : '1';
          }
         while(ii<l && message[ii]!='1')
         {
               ii++;
         }
    }
    string x=message.substr(message.length()-crc.length());
    cout<<x;
    for(char i: x)
      if(i=='1')
      {
            cout<<"FALSE";
            return 0;
      }
      cout<<"TRUE";
      return 0;
     }
                    if(choice==3)
                    {
                        return 0;
                    }
    return 0;
}