//10.6 - Encryption Program - Dirk Henkemans 
//Prima Publishing
//A text data encryption program
#include <iostream>
#include <fstream>
using namespace std;

class Encryption
{
     fstream file1;//source file
     fstream file2;//destination file
     
     public:
     Encryption::Encryption(char* filename1, char* filename2)
     {
          file1.open(filename1, ios::in | ios::out | ios::binary);
          file2.open(filename2, ios::out|ios::binary);
     }     
     
     //encrypts the file
     void Encrypt(void)
     {
          char currentByte;
          bool currentBit;
          
          int index = 0;
          
          //sets the pointers to the beginning of the file
          file1.seekg (0, ios::beg);
          file2.seekp (0, ios::beg);
          
          //reads the first value
          file1.read(&currentByte, 1);
          while(file1.good())
          { 
               //loop for four bits
               for(int c = 0; c < 4; c++)
               {
                    //finds out if the first bit is a one
                    currentBit = (int)((unsigned char)currentByte / 128);
                    //shifts the byte over
                    currentByte <<= 1;
                    
                    //if the first bit was a one then we add it to the end
                    if(currentBit)
                    {
                         currentByte += 1;
                    }
               }
               
               //writes the character               
               file2.write(&currentByte, 1);
               
               //increments the pointer
               file1.seekg (++index);
               file2.seekp (index);
               
               //reads the next value
               file1.read(&currentByte, 1);
          }
     }     

     //closes both of the files
     void close(void)
     {
          file1.close();
          file2.close();
     }
};

int main( void )
{
     cout<< "Welcome to the S.A.S encryption program.";
     Encryption delta("dragons.txt", "output1.txt");
     delta.Encrypt();
     delta.close();
     
     Encryption gamma("output1.txt", "output2.txt");
     gamma.Encrypt();
     delta.close();
     return 0;
}