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

int str_to_int(char* str) {
  int output = 0;

  for (int i = 0; i < strlen(str); i++) {
    output *= 10;
    output += str[i] - '0';
  }

  return output;
}

void invalid_args(int argc) {
  if (argc < 4 && argc > 5) {
    printf("nuhuh\n");
    exit(1);
  }
}

int random_len(int min_length, int max_length) {
  return rand() % (max_length - min_length + 1) + min_length;
}

char* random_str(int length, char* symbols) {
  char* str = malloc(sizeof(char) * (length + 1));

  for (int i = 0; i < length; i++) {
    int index = rand() % strlen(symbols);
    str[i] = symbols[index];
  }

  str[length] = '\0';

  return str;
}

int main(int argc, char** argv) {
  invalid_args(argc);
  srand(time(NULL));

  int min_length = str_to_int(argv[1]);
  int max_length = str_to_int(argv[2]);

  int length = random_len(min_length, max_length);

  if (argc != 4) {
    char* password = random_str(length, argv[4]);
    puts(password);
    free(password);
  } else {
    char* password = random_str(length, argv[3]);
    puts(password);
    free(password);
  }
}