use clap::{ArgMatches, SubCommand, App, Arg};
use crate::cmd::{Command, CommandError};
use yubico_manager::Yubico;
use yubico_manager::config::{Config, Mode, Slot};
use std::ops::Deref;

pub struct CommandImpl;

impl Command for CommandImpl {
    fn name(&self) -> &str { "chall" }

    fn subcommand<'a>(&self) -> App<'a, 'a> {
        SubCommand::with_name(self.name()).about("Yubikey challenge-response hmac")
            .arg(Arg::with_name("challenge").short("c").long("challenge").takes_value(true).help("Challenge"))
            .arg(Arg::with_name("challenge-hex").short("x").long("challenge-hex").takes_value(true).help("Challenge HEX"))
            .arg(Arg::with_name("json").long("json").help("JSON output"))
    }

    fn run(&self, _arg_matches: &ArgMatches, sub_arg_matches: &ArgMatches) -> CommandError {
        let challenge_bytes: Vec<u8>;
        if let Some(challenge) = sub_arg_matches.value_of("challenge") {
            challenge_bytes = challenge.as_bytes().to_vec();
        } else if let Some(challenge_hex) = sub_arg_matches.value_of("challenge-hex") {
            challenge_bytes = hex::decode(challenge_hex)?;
        } else {
            return simple_error!("Challenge must assigned");
        }

        // Challenge can not be greater than 64 bytes
        if challenge_bytes.len() > 64 {
            return simple_error!("Challenge bytes is: {}, more than 64", challenge_bytes.len());
        }

        let mut yubi = Yubico::new();

        if let Ok(device) = yubi.find_yubikey() {
            success!("Found key, Vendor ID: {:?} Product ID {:?}", device.vendor_id, device.product_id);

            let config = Config::default()
                .set_vendor_id(device.vendor_id)
                .set_product_id(device.product_id)
                .set_variable_size(true)
                .set_mode(Mode::Sha1)
                .set_slot(Slot::Slot2);

            // In HMAC Mode, the result will always be the SAME for the SAME provided challenge
            let hmac_result = yubi.challenge_response_hmac(&challenge_bytes, config).unwrap();

            // Just for debug, lets check the hex
            let v: &[u8] = hmac_result.deref();
            let hex_string = hex::encode(v);

            success!("{}", hex_string);
        } else {
            warning!("Yubikey not found");
        }

        Ok(())
    }
}