#!/usr/bin/env runrs

//! ```cargo
//! [dependencies]
//! rand = "0.8.5"
//! clap = { version = "4.1.8", features = ["derive"] }
//! ```

use clap::{arg, Parser};
use rand::RngCore;
use std::process::exit;

const ENGLISH_LOWER: &'static str = "abcdefghijklmnopqrstuvwxyz";
const ENGLISH_UPPER: &'static str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const NUMBER: &'static str = "0123456789";
const SPECIAL: &'static str = ".,/<>;:[]{}-=_+!@#$%^&*()~";

#[derive(Parser, Debug)]
#[command(author, version, about, long_about = None, bin_name = "makepassword.rs")]
struct Args {
    /// Password length
    #[arg(short, long)]
    length: Option<u32>,

    /// Chars (e.g. a - lower case alphabet, A - UPPER CASE ALPHABET, n|N|# - number, * - special)
    #[arg(short, long)]
    chars: Option<String>,
}

fn main() {
    let args: Args = Args::parse();

    let mut a = false;
    let mut A = false;
    let mut n = false;
    let mut s = false;
    match args.chars {
        None => {
            a = true;
            A = true;
            n = true;
        }
        Some(chars) => {
            for c in chars.chars() {
                match c {
                    'a' => a = true,
                    'A' => A = true,
                    'n' | 'N' | '#' => n = true,
                    '*' => s = true,
                    _ => {}
                }
            }
        }
    }

    if !a && !A && !n && !s {
        eprintln!("No chars selected.");
        exit(1);
    }

    let mut str = "".to_string();
    if a {
        str += ENGLISH_LOWER;
    }
    if A {
        str += ENGLISH_UPPER;
    }
    if n {
        str += NUMBER;
    }
    if s {
        str += SPECIAL;
    }
    let chars = str.chars().collect::<Vec<_>>();

    let mut rng = rand::thread_rng();
    let mut pass = String::new();

    let len = args.length.unwrap_or(18);
    for _ in 0..len {
        pass.push(chars[rng.next_u32() as usize % chars.len()]);
    }

    println!("{}", pass);
}

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