base37.rs

fn base37_encode(text: String) -> u64 {
    let mut hash = 0;

    for ch in text.chars().take(12) {
        let modifier = match ch {
            'a'...'z' => 1  + (ch as u64 - 'a' as u64),
            'A'...'Z' => 1  + (ch as u64 - 'A' as u64),
            '0'...'9' => 33 + (ch as u64 - '0' as u64),
            _ => 0,
        };
        hash *= 37;
        hash += modifier;
    }

    return hash;
}

fn base37_decode(hash: u64) -> String {
    let mut hash = hash;
    let mut chars = Vec::new();

    while hash != 0 {
        if chars.len() >= 12 {
            break;
        }

        let modifier = (hash % 37) as u8;
        hash /= 37;

        match modifier {
            1...26  => chars.push((modifier + 96) as char),
            27...36 => chars.push((modifier + 21) as char),
            _       => chars.push(' '),
        }
    }

    return chars.into_iter().rev().collect();
}

fn main() {
    let username = "hikilaka".to_string();
    let hash = base37_encode(username);

    println!("encoded: {}", hash);
    println!("decoded: {}", base37_decode(hash));
}