unDec

//Encode/decode symbols from cp1251 by their codes

#include "stdafx.h"
#include <iostream>
#include <cstdio>
#include <Windows.h>
#include <fstream>
#include <cstring>
#include <cctype>

#define inp_by_h 200

using namespace std;

short int encode_decode(char *ptr, int size);
short int write(char *ptr);
void pause_exit();

class intt {
    short int i;
    int error;
public:
    intt() { i = 0; error = 0; }
    friend istream &operator>>(istream &stream, intt &i);
    friend int main(int argc, char *argv[]);
};

istream &operator>>(istream &stream, intt &i) {
    stream >> i.i;
    if (i.i != 1 && i.i != 2 && i.i != 3) i.error = 1;
    //cout << '#' << (char)i.i << '# ' << (int)i.error << endl;
    //system("pause");

    return stream;
}

int main(int argc, char *argv[])
{
    // Add support of CP1251 in Win console
    SetConsoleCP(1251);
    SetConsoleOutputCP(1251);

    int short repeat = 1; // Loop

    // Step 1

    // If using terminal argument - skip choice once
    int once = 1;
    if (!argv[1] || !once) cout << "Hello there! This program can ENCODE/DECODE your text";
    do
    {
        intt start_ans;
        if (!argv[1] || !once)
        {
            do
            {
                cout << "\n\nWhat do you want to do?\n\n"
                    << " [1] Open file with the text\n [2] Write text here\n [3] Exit\n\n"
                    << "Your answer will be: ";
                fflush(stdin);
                cin >> start_ans;
            } while (start_ans.error);
        }
        else
            start_ans.i = 1;

        if (start_ans.i == 1) // Open
        {
            char f_name[90];
            if (!argv[1] || !once)
            {
                cout << "\nEnter file full path or name: ";
                fflush(stdin);
                gets(f_name);
            }
            else
            {
                strcpy(f_name, argv[1]);
                once = 0; // argv[1] must work only at first iteration of main loop
            }

            // Open FILE stream for reading
            ifstream f_stream(f_name, ios::in | ios::binary);
            if (!f_stream)
            {
                cout << "\nError in opening \"" << f_name << "\"...\n";
                pause_exit();
                return 1;
            }
            else
                cout << "\nFile successfully opened!\n";

            // Find the number of characters in the file
            int chs_in_file = 0;
            streamoff a = 0, b = 0;
            a = f_stream.tellg();
            f_stream.seekg(0, ios::end);
            b = f_stream.tellg();
            f_stream.seekg(0, ios::beg);
            chs_in_file = (int)(b - a);

            // Allocate memory
            char *ptr_file_buf = new char[chs_in_file + 1]; // +1 for '\0'
            if (!*ptr_file_buf)
            {
                cout << "\nError in memory allocation...\n\n";
                pause_exit();
                return 1;
            }
            char *ptr_file_start = ptr_file_buf;

            // Copy text from the file to buffer
            cout << "\nRead \"" << chs_in_file << "\" chars in \"" << f_name << "\". Preview:\n\n";
            register int i = 0;
            while (f_stream.get(*ptr_file_buf))
            {
                if (i < 301) cout << *ptr_file_buf;
                i++;
                ptr_file_buf++;
            }
            *ptr_file_buf = '\0'; // Edge of array (like EOF in file)
            f_stream.close();
            if (i > 300) cout << " ...etc.";

            // Call encode/decode function
            if (!encode_decode(ptr_file_start, chs_in_file + 1)) cout << "\nError in coding/decoding process!";

            delete[] ptr_file_start;
            ptr_file_buf = nullptr;
            ptr_file_start = nullptr;
        }
        if (start_ans.i == 2)
        {
            char input_buff[inp_by_h];
            cout << "\nEnter your text(not more than " << inp_by_h << " symbols): ";
            fflush(stdin);
            gets(input_buff);
            if (!encode_decode(input_buff, inp_by_h)) cout << "\nError in coding/decoding process!";
        }
        if (start_ans.i == 3) repeat = 0; // Exit

        cout << "\n\n";
    } while (repeat);

    pause_exit();
    return 0;
}

short int encode_decode(char *ptr, int size)
{
    // Step 2
    short int c_dc_ans = 0;

    cout << "\n\nEnter keyword: ";
    char key_word[90];
    gets(key_word);
    int koef = strlen(key_word);
    do
    {
        cout << "\n\nSelect one of those options:\n\n" << " [1] Encode text\n" << " [2] Decode text\n\n" << "Your choice: ";
        cin >> c_dc_ans;
    } while (c_dc_ans != 1 && c_dc_ans != 2);

    char *outp_mas = new char[size]; // Array for encoded/decoded characters
    if (!*outp_mas) return 0;
    char *outp_mas_start = outp_mas;
    int val; // var for int number of processed character

    while (*ptr != '\0')
    {
        val = (int)*ptr;

        if (c_dc_ans == 1)
            val += koef;

        if (c_dc_ans == 2)
            val -= koef;

        *outp_mas = (char)val;
        ptr++;
        outp_mas++;
    }
    *outp_mas = '\0'; // edge for next step while()

    if (c_dc_ans == 1) cout << "\nEncoded successfully";
    if (c_dc_ans == 2) cout << "\nDecoded successfully";

    if (!write(outp_mas_start))
    {
        cout << "\nError in writing/displaying\n\n";
        return 0;
    }

    delete[] outp_mas_start;
    outp_mas = nullptr;
    outp_mas_start = nullptr;
    return 1;
}

short int write(char *ptr)
{
    // Step 3
    short int wr_ans = 0;

    do
    {
        cout << "\n\nSelect one of those options:\n\n" << " [1] Write text to the file\n" << " [2] Display text on the screen\n\n" << "Your choice: ";
        cin >> wr_ans;
    } while (wr_ans != 1 && wr_ans != 2);
    switch (wr_ans)
    {
    case 1:
    {
              cout << "\nEnter file name or full path: ";
              char file_name[90];
              fflush(stdin);
              gets(file_name);

              ofstream write_group(file_name, ios::app | ios::binary);
              if (!write_group) return 0;

              while (*ptr != '\0')
              {
                  write_group << *ptr;
                  ptr++;
              }
              cout << "\nWrited successfuly";

              write_group.close();
              return 1;
              break;
    }
    case 2:
    {
              cout << "\nText:\n\n";
              while (*ptr != '\0')
              {
                  cout << *ptr;
                  ptr++;
              }

              return 1;
              break;
    }
    }

    return 0;
}

void pause_exit()
{
    char pause[90];
    cout << "\nPress Enter for exit...";
    fflush(stdin);
    gets(pause);
}