main.cpp

#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>

#ifdef __linux__
#include <stdio.h>
#include <unistd.h>
#include <termios.h>
#elif _WIN32
#include <conio.h>
#endif

using namespace std;

string pool = "ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz123456789!@#$%^&*()";
string upp = "ABCDEFGHJKLMNPQRSTUVWXYZ";
string low = "abcdefghijkmnopqrstuvwxyz";
string num = "123456789";
string sym = "!@#$%^&*()";

string shuffle(string input) {
    string output = "";
    while (input.size() > 0) {
        int idx = rand() % input.size();
        output += input[idx];
        input = input.substr(0, idx) + input.substr(idx + 1);
    }
    return output;
}

string generate(int length) {
    pool = shuffle(pool);
    upp = shuffle(upp);
    low = shuffle(low);
    num = shuffle(num);
    sym = shuffle(sym);

    string password = "";
    int mod = pool.size();

    password += upp[rand() % upp.size()];
    password += low[rand() % low.size()];
    password += num[rand() % num.size()];
    password += sym[rand() % sym.size()];

    length -= 4;
    while (length > 0) {
        password += pool[rand() % mod];
        length --;
    }

    password = shuffle(password);
    return password;
}

bool try_parse_int(string input) {
    for (char c : input)
        if (c < '0' or c > '9')
            return false;
    return true;
}

int parse_int(string input) {
    int parsed = 0;
    for (char c : input) {
        parsed *= 10;
        parsed += c - '0';
    }
    return parsed;
}

#ifdef __linux__
char getch(void) {
    struct termios oldt, newt;
    char ch;
    tcgetattr(STDIN_FILENO, &oldt);
    newt = oldt;
    newt.c_lflag &= ~(ICANON | ECHO);
    tcsetattr(STDIN_FILENO, TCSANOW, &newt);
    ch = getchar();
    tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
    return ch;
}
#endif

int main() {
    srand(time(nullptr));

    while (true) {
        string input;
        int length;

        #ifdef __linux__
        system("clear");
        #elif _WIN32
        system("cls");
        #endif

        cout << "Enter the password length: ";
        getline(cin, input);
        while (try_parse_int(input) == false or parse_int(input) < 8) {
            #ifdef __linux__
            system("clear");
            #elif _WIN32
            system("cls");
            #endif

            cout << "An error occurred! Possible causes:" << endl;
            cout << "  Your input is not a number" << endl;
            cout << "  Your input is a number less than 8" << endl << endl;
            cout << "Enter the password length: ";
            getline(cin, input);
        }
        length = parse_int(input);

        while (true) {
            #ifdef __linux__
            system("clear");
            #elif _WIN32
            system("cls");
            #endif

            cout << "Generated password: " << generate(length) << endl;
            cout << "r - regenerate" << endl;
            cout << "m - return to the menu" << endl;
            cout << "q - quit" << endl;
            cout << "Enter your option... ";
            char opt = getch();
            if (opt == 'q') {
                cout << endl;
                return 0;
            }
            while ((opt == 'r' or opt == 'm' or opt == 'q') == false)
                opt = getch();
            if (opt == 'q') {
                cout << endl;
                return 0;
            }
            else if (opt == 'm')
                break;
        }
    }
    return 0;
}