use clap::Parser;
use rand::{RngCore, rngs::OsRng};
use std::io::Write;
use std::process::{Command, Stdio};

#[derive(Parser, Debug)]
#[command(name = "random_password", author, version = "0.1.0")]
/// Generates a random password, that's likely to work for most signups
struct Args {
    /// Copy to clipboard instead of printing to stdout
    #[arg(short = 'c', long = "clipboard")]
    is_clipboard: bool,
    /// Length of the generated password
    #[arg(value_name = "LENGTH")]
    pass_length: u8,
}

#[derive(Default)]
struct CharDistro {
    uppercase: usize,
    lowercase: usize,
    numerical: usize,
    special: usize,
}

impl CharDistro {
    pub fn from(s: &str) -> Self {
        let mut d = Self::default();

        for c in s.chars() {
            if c.is_uppercase() {
                d.uppercase += 1;
            } else if c.is_lowercase() {
                d.lowercase += 1;
            } else if c.is_digit(10) {
                d.numerical += 1;
            } else {
                d.special += 1;
            }
        }

        d
    }

    pub fn all_nonzero(&self) -> bool {
        self.uppercase > 0 && self.lowercase > 0 && self.numerical > 0 && self.special > 0
    }
}

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

    let mut key = [0_u8; 256];

    loop {
        OsRng.fill_bytes(&mut key);
        pass = encode_to_password(&key);
        trimmed = &pass[..args.pass_length as usize];

        let distro = CharDistro::from(trimmed);
        let is_enough_special = distro.special >= (args.pass_length / 10 + 1) as usize;

        if distro.all_nonzero() && is_enough_special && has_two_special(trimmed) {
            break;
        }
    }

    if args.is_clipboard {
        let pbcopy = Command::new("wl-copy")
            .stdin(Stdio::piped())
            .spawn()
            .expect("Failed to start wl-copy");

        pbcopy.stdin.unwrap().write(trimmed.as_bytes()).unwrap();
    } else {
        println!("{}", trimmed);
    }
}

fn encode_to_password(key: &[u8; 256]) -> String {
    let mut pass = String::new();

    for bits in key {
        let c = bits & 0o77;

        if c <= 25 {
            pass.push((c + 65) as char);
        } else if c <= 51 {
            pass.push((c + 97 - 26) as char);
        } else if c <= 61 {
            pass.push((c + 48 - 52) as char);
        } else if c == 62 {
            pass.push('-');
        } else {
            pass.push(';');
        }
    }

    pass
}

fn has_two_special(s: &str) -> bool {
    let mut special_1 = 'a';

    for c in s.chars() {
        if !c.is_ascii_alphanumeric() && special_1 == 'a'{
            special_1 = c;
        } else if !c.is_ascii_alphanumeric() {
            return true;
        }
    }

    false
}