#include <iostream>
#include <string.h>
#include <fstream>
#include <string>

using namespace std;

char convertToHex(char c);

int main(int argc, char *argv[]){

    if (argc != 4){
        cout << endl;
        cout << "*********** JpgFromText ***********" << endl << endl;
        cout << "You haven't provided all the parameters." << endl;
        cout << "The correct format is:" << endl << endl;
        cout << "\tjpgfromtext.exe [-f/-r] <input txt file> <output jpg file>" << endl << endl;
        cout << "-f - foreward direction" << endl;
        cout << "-r - reverse direction" << endl;
        return 1;
    }

    if (strcmp(argv[1], "-f") != 0 && strcmp(argv[1], "-r") != 0){
        cout << "Invalid options parameter: options are -f or -r." << endl;
        return 1;
    }

    ifstream is(argv[2]);
    ofstream os(argv[3], ofstream::binary);

    char bout = 0x00;
    char boutprev = bout;
    bool control = true;

    if (strcmp(argv[1], "-f") == 0){
        while (is.good()) {
            char b = is.get();
            b = convertToHex(b);

            if (b != (char)0xff){
                if (control) {
                    bout = bout | b;
                    control = false;
                }
                else {
                    bout = bout << 4;
                    bout = bout | b;
                    os.put(bout);
                    if (bout == 0xd9 && boutprev == 0xff) break;
                    boutprev = bout;
                    bout = 0x00;
                    control = true;
                }
            }
        }
    } else {
        string data;
        while (is.good()) {
            data += is.get();
        }
        string reversed;
        string::iterator iter = data.end();
        iter -= 3;
        for (; iter != data.begin(); iter -= 2){
            string::iterator temp;
            temp = iter;
            reversed += *temp;
            temp++;
            reversed += *(temp);
        }

        for(string::iterator iter = reversed.begin(); iter!=reversed.end(); iter++) {
            char b = *iter;

            b = convertToHex(b);
            if (b != (char)0xff){
                if (control) {
                    bout = bout | b;
                    control = false;
                }
                else {
                    bout = bout << 4;
                    bout = bout | b;
                    os.put(bout);
                    if (bout == (char)0xd9 && boutprev == (char)0xff){
                        is.close();
                        os.close();
                        return 0;
                    }
                    boutprev = bout;
                    bout = 0x00;
                    control = true;
                }
            }
        }


    }

    os.close();
    is.close();
    return 0;
}

char convertToHex(char c){
    char b;
    switch (c){
    case '0':b = 0x00;
        break;
    case '1':b = 0x01;
        break;
    case '2':b = 0x02;
        break;
    case '3':b = 0x03;
        break;
    case '4':b = 0x04;
        break;
    case '5':b = 0x05;
        break;
    case '6':b = 0x06;
        break;
    case '7':b = 0x07;
        break;
    case '8':b = 0x08;
        break;
    case '9':b = 0x09;
        break;
    case 'a':b = 0x0a;
        break;
    case 'b':b = 0x0b;
        break;
    case 'c':b = 0x0c;
        break;
    case 'd':b = 0x0d;
        break;
    case 'e':b = 0x0e;
        break;
    case 'f':b = 0x0f;
        break;
    default: b = 0xff;
    }

    return b;
}