#define _XOPEN_SOURCE
#define DOUBLE_ALPHA 52
#include <cs50.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

int main(int argc, string argv[])
{
    // prompt user for hash password from the cmd line, limited to 1 argument only
    if (argc != 2)
    {
        printf("Usage: ./crack hash\n");
        return 1;
    }

    // get "salt" for crypt() by retrieving the first two characters of argv[1]
    char salt[3];
    salt[0] = argv[1][0];
    salt[1] = argv[1][1];

    //  password may have up to four characters in length
    char password[5];
    string alphabets = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

    // testing for password with one character length
    for (int i = 0; i < DOUBLE_ALPHA; i++)
    {
        password[1] = '\0';
        password[0] = alphabets[i];
        string hash2 = crypt(password, salt);
        if (strcmp(argv[1], hash2))
        {
            printf("Password: %s\n", password);
            return 0;
        }
    }

    // testing for password with two characters length
    for (int i = 0; i < DOUBLE_ALPHA; i++)
    {
        password[2] = '\0';
        password[0] = alphabets[i];
        for (int j = 0; j < DOUBLE_ALPHA; j++)
        {
            password[1] = alphabets[j];
            string hash2 = crypt(password, salt);
            if (strcmp(argv[1], hash2))
            {
                printf("Password: %s\n", password);
                return 0;
            }
        }
    }

    // testing for password with three characters length
    for (int i = 0; i < DOUBLE_ALPHA; i++)
    {
        password[3] = '\0';
        password[0] = alphabets[i];
        for (int j = 0; j < DOUBLE_ALPHA; j++)
        {
            password[1] = alphabets[j];
            for (int k = 0; k < DOUBLE_ALPHA; k++)
            {
                password[2] = alphabets[k];
                string hash2 = crypt(password, salt);
                if (strcmp(argv[1], hash2))
                {
                    printf("Password: %s\n", password);
                    return 0;
                }
            }
        }
    }

    // testing for password with four characters length
    for (int i = 0; i < DOUBLE_ALPHA; i++)
    {
        password[4] = '\0';
        password[0] = alphabets[i];
        for (int j = 0; j < DOUBLE_ALPHA; j++)
        {
            password[1] = alphabets[j];
            for (int k = 0; k < DOUBLE_ALPHA; k++)
            {
                password[2] = alphabets[k];
                for (int l = 0; l < DOUBLE_ALPHA; l++)
                {
                    password[3] = alphabets[l];
                    string hash2 = crypt(password, salt);
                    if (strcmp(argv[1], hash2))
                    {
                        printf("Password: %s\n", password);
                        return 0;
                    }
                }
            }
        }
    }
}