/*
This is a frequency sustitution implementation by Sourena Maroofi
THIS IS AN EXPERIMENTAL VERSION...USE IT AT YOUR OWN RISK.

*/

#include <iostream>
#include <string>
#include <fstream>

#ifndef freqsub_h
#include "freqsub.h"	
#endif

using namespace std;
/********************************************************************************/
 freqsub::freqsub(void)
{
      // inputFile="b.txt";
        //outputFile="c.txt";
        codec=true;   //encoding mode default
                   
                   
}
/********************************************************************************/
int freqsub::freqsub_encode(void)
{
    ifstream inFile;
    inFile.open(inputFile,ios::in|ios::binary);
    if (!inFile.is_open())
    {
                          cout<<endl<<"can not open input file";  
                          cout<<(string)inputFile;
                          cout<<endl;
                          return -1;
    }
    ofstream outFile;
    outFile.open(outputFile,ios::out|ios::binary);
    if (!outFile.is_open())
    {
                       cout<<endl<<"can not open output file";  
                       cout<<(string)outputFile;
                       cout<<endl;
                       return -1;    
    }   
    st=new struct mystat [256];
    for(int i=0;i<256;i++)
    {
            (st+i)->count=0;
            (st+i)->used=false;
    }
    unsigned char * byte;
    byte=new unsigned char [1];  
  unsigned  long int sizef;
    inFile.seekg(0,ios::end);
    sizef=inFile.tellg();
    cout<<"file size is : "<<sizef;
    inFile.seekg(0,ios::beg);
    unsigned long int y=0;
    while ( y<sizef)
    {
          inFile.read((char *)byte,1);
          ((st+(*byte))->count)++;
          y++;
    
    }    
   inFile.seekg(0,ios::beg);  
    int i=0;
    unsigned char *b_array=new unsigned char [256];
    
    while(i<256)
    {
        b_array[i]=(unsigned char)find_max();
        i++;      
    }
    
          
    unsigned char *c_array=new unsigned char[256];
    for(int i=0;i<256;i++)
    {
            c_array[b_array[i]]=i;
    }
    
    outFile.write((char *)b_array,256);
    y=0;
    while (y<sizef)
    {
        inFile.read((char *)byte,1); 
        outFile.write((char *)(&c_array[(*byte)]),1);  
        y++;
    }
    
    inFile.close();
    outFile.close();
    return 1;
}
/*************************************************************************/
int freqsub::freqsub_decode()
{   
     ifstream inFile;
     ofstream outFile;
     inFile.open(inputFile,ios::in|ios::binary);
     if (!inFile.is_open())
    {
                          cout<<endl<<"can not open input file";  
                          cout<<(string)inputFile;
                          cout<<endl;
                          return -1;
    }
    outFile.open(outputFile,ios::out|ios::binary);
    if (!outFile.is_open())
    {
                       cout<<endl<<"can not open output file";  
                       cout<<(string)outputFile;
                       cout<<endl;
                       return -1;    
    }   
    inFile.seekg(0,ios::end);
    unsigned long int sizef,y;
    y=0;
    sizef=inFile.tellg();
    if (sizef==0)
    {
                 cout<<"file is empty or error occured!!!"<<endl;
                 return -1;
    }
    inFile.seekg(0,ios::beg);
    unsigned char * b_array;
    b_array=new unsigned char [256];
    unsigned char * byte;
    byte=new unsigned char [1];
    inFile.read((char *)b_array,256);
    y+=256;
    while (y<sizef)
    {
          inFile.read((char *)byte,1);
          outFile.write((char *)&b_array[(*byte)],1);
          y++;
    }
    
    return 1;
}
/**************************************************************************/
int freqsub::find_max(void)
{
     int j=-1;
     unsigned long int max;
     max=0;
     for (int i=0;i<256;i++)
     {
           if (st[i].count>=max && st[i].used==false)
           {
                                max=st[i].count;
                                j=i;
           }         
     }
     st[j].used=true;
     return j;
}
/********************************************************************************/