/*
ospwgen.c - old school password generator - billy
5.5.2022
*/

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>


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

int rn;                                         //initialize integer to hold random numbers
char *cmd=argv[0];                              //store command used to run program (for usage notice)
char a_upper[]="ABCDEFGHIJKLMNOPQRSTUVWXYZ";    //initialize array of uppercase
char a_upperc[]="BCDFGHJKLMNPQRSTVWXYZ";        //initialize array of uppercase consonants
char a_upperv[]="AEIOU";                        //initialize array of uppercase vowels
char a_lower[]="abcdefghijklmnopqrstuvwxyz";    //initialize array of lowercase
char a_lowerc[]="bcdfghjklmnpqrstvwxyz";        //initialize array of lowercase consonants
char a_lowerv[]="aeiou";                        //initialize array of lowercase vowels
char a_digit[]="0123456789";                    //initialize array of digits
char a_symbl[]="!@#$%^&*()-+;:,.";              //initialize array of symbols

if (argv[1]){                                   //if argument 1 is not null

    srand(time(NULL));                          //seed random number generator with date
    int alength=(int)strlen(argv[1]);           //get length of command line argument 1 (format string)
for (int i=0; i<alength ; i++)                  //iterate over each char in format string and generate char
    {
        char c=argv[1][i];
        switch(c){
            case 'u' :
                rn = rand() % 26;
                printf("%c",a_upper[rn]);
                break;
            case 'l' :
                rn = rand() % 26;
                printf("%c",a_lower[rn]);
                break;
            case 'c' :
                rn = rand() % 21;
                printf("%c",a_lowerc[rn]);
                break;
            case 'v' :
                rn = rand() % 5;
                printf("%c",a_lowerv[rn]);
                break;
            case 'C' :
                rn = rand() % 21;
                printf("%c",a_upperc[rn]);
                break;
            case 'V' :
                rn = rand() % 5;
                printf("%c",a_upperv[rn]);
                break;
            case 'd' :
                rn = rand() % 10;
                printf("%c",a_digit[rn]);
                break;
            case 's' :
                rn = rand() % 16;
                printf("%c",a_symbl[rn]);
                break;
        }
    }
 printf("\n");                                  //print newline and exit after displaying generated output
 return 0;
 }
 else                                           //else print usage and exit
    printf("Format string required as argument!\n");
    printf("Usage: %s <format string>\n",cmd);
    printf("u = uppercase letter\n");
    printf("l = lowercase letter\n");
    printf("c = consonant\n");
    printf("v = vowel\n");
    printf("C = uppercase consonant\n");
    printf("V = uppercase vowel\n");
    printf("d = digit\n");
    printf("s = symbol\n");
return 0;
}