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extern crate ndarray;
extern crate rand;
#[macro_use]
extern crate serde;
extern crate serde_json;
mod trigram;
use rand::prelude::*;
use trigram::create_trigrams;
const LENGTH: usize = 10;
const THRESHOLD: f64 = 125729.;
const ALPHABET: &'static str = "abcdefghijklmnopqrstuvwxyz";
pub struct PasswordGenerator {
pik : f64,
ranno : f64,
sum : u32,
trigram: ndarray::Array3<u16>,
output: String
}
impl Iterator for PasswordGenerator {
type Item = String;
fn next(&mut self) -> Option<Self::Item> {
self.start();
if self.pik == 0. && self.ranno == 0. {
None
} else {
Some(self.calculate_next())
}
}
}
impl Default for PasswordGenerator {
fn default() -> Self {
let mut retval = PasswordGenerator {
pik: 0.,
ranno: 0.,
sum: 0,
trigram: create_trigrams(),
output: String::with_capacity(LENGTH)
};
retval
}
}
fn to_character(index : usize) -> char {
ALPHABET.get(index..index+1).unwrap().chars().next().unwrap()
}
fn index_at(value: &str, idx: usize) -> usize {
let c = value.get(idx..idx+1).unwrap().chars().next().unwrap() as u8;
(c - ('a' as u8)) as usize
}
impl PasswordGenerator {
fn start(&mut self) {
self.output.clear();
self.pik = random::<f64>();
self.ranno = self.pik * THRESHOLD;
self.sum = 0;
self.get_starting_point();
}
fn get_starting_point(&mut self) {
for c1 in 0..26 {
for c2 in 0..26 {
for c3 in 0..26 {
self.sum += self.trigram[[c1, c2, c3]] as u32;
if self.sum as f64 > self.ranno {
self.output.push(to_character(c1));
self.output.push(to_character(c2));
self.output.push(to_character(c3));
return;
}
}
}
}
}
fn calculate_next(&mut self) -> String {
let mut nchar = self.output.len();
while (nchar < LENGTH) {
let c1 = index_at(&self.output, nchar-2);
let c2 = index_at(&self.output, nchar-1);
self.sum = 0;
for c3 in 0..26 {
self.sum += self.trigram[[c1, c2, c3]] as u32;
}
if self.sum == 0 {
return "".to_owned()
}
self.pik = random::<f64>();
self.ranno = self.pik * self.sum as f64;
self.sum = 0;
for c3 in 0..26 {
self.sum += self.trigram[[c1, c2, c3]] as u32;
if self.sum as f64 > self.ranno {
self.output.push(to_character(c3));
break;
}
}
nchar += 1;
}
self.output.clone()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn it_works() {
let mut generator = PasswordGenerator::default();
let password1 = generator.next().unwrap();
let password2 = generator.next().unwrap();
println!("{} / {}", password1, password2);
assert!(password1 != password2);
}
}