#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#define KEY_DIVIDOR 256
#define CAESAR_VALUE 1
#define MAX_INPUT_LENGTH 256
#define MAX_COUNTER_LENGTH 255

int main(int argc, char **argv)
{
  char user_input[MAX_INPUT_LENGTH];
  char reverse_input[MAX_INPUT_LENGTH];
  int read;
  int counter = 0;
  int space_counter = 0;
  int key;
  int key_holder = 0;
  int m = 0;
  int space_counter_holder = 0;
 // int k = 0;
  read = getchar();
  while((read != EOF) && (read != '\n') && (read != '\0')) // todo: ctrl d,plain text bez njuline
  {
    if(counter > MAX_COUNTER_LENGTH) // TODO: handle if both cases appear, that its longer than 254(ask nikola for length) and something from the below , this errror should be printed first
    {
      printf("[ERR] too many characters\n");
      return -1;
    }
    if((isupper(read)) || (!isalpha(read) && !isspace(read)))
    {
      printf("[ERR] invalid characters\n");
      return -2;
    }
    else
    {
      if(isspace(read))
      {
        space_counter++;
      }
      user_input[counter++] = read;
      read = getchar();
    }
  }
  user_input[counter] = '\0';
  if(counter-space_counter == 0)
  {
    printf("plain text: %s", user_input);
    printf("encrypted text: \n");
  }
  else
  {
    printf("plain text: %s", user_input);
    space_counter_holder = counter - space_counter;
    key = KEY_DIVIDOR % (space_counter_holder);
    printf("%d",key);
    if(key == 0)
    {
      for(int i = counter-1,k=0; i>=0; i--, k++)
      {
        reverse_input[k] = user_input[i];
      }
      reverse_input[counter] = '\0';
      printf("encrypted text: %s\n", reverse_input);
    }
    else
    {
      for(m=0; m<counter; m++)
      {
        key_holder = user_input[m];
        if(key_holder >=  'a' && key_holder <= 'z')
        {
          key_holder += key;
          if(key_holder > 'z')
          {
            key_holder = key_holder - 'z' + 'a' - CAESAR_VALUE;
          }
          user_input[m] = key_holder;
        }
      }
      printf("encrypted text: %s\n",user_input);
    }
  }
  return 0;
}