// First we create our corpus, or set of characters that will go in our password
const PASSWORD_CHARS: &str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

// Import the random generator and the interator random extension trait
:dep rand
extern crate rand;
use rand::{seq::IteratorRandom, thread_rng, Rng};

// Then we create our password generator
fn gen_passwd(len: u16, rng: &mut impl Rng) -> String {
    // The password buffer
    let mut password = String::new();
    
    // Loop trough 0 up to our password length
    for _ in 0..len {
        // Add a character
        password.push(
            PASSWORD_CHARS // Out of our password character list
                .chars() // As an iterator over the characters
                .choose(rng) // This choose method comes form the `rand::seq::IteratorRandom` import
                .expect("Empty iterator for password chars"), // Expect won't fail unless our corpus was empty
        );
    }
    
    password
}

// To use our function we have to first create a random generator
let mut rng = thread_rng();

// Then we can generate random numbers!
gen_passwd(32, &mut rng)

gen_passwd(12, &mut rng)

gen_passwd(124, &mut rng)