//! Byzantine participant that sends nullify and finalize messages for the same view.

use crate::{
    simplex::types::{Finalize, Nullify, View, Voter},
    Supervisor, Viewable,
};
use commonware_codec::{Decode, Encode};
use commonware_cryptography::{Hasher, Signer};
use commonware_p2p::{Receiver, Recipients, Sender};
use commonware_runtime::{Handle, Spawner};
use std::marker::PhantomData;
use tracing::debug;

pub struct Config<C: Signer, S: Supervisor<Index = View, PublicKey = C::PublicKey>> {
    pub crypto: C,
    pub supervisor: S,
    pub namespace: Vec<u8>,
}

pub struct Nuller<
    E: Spawner,
    C: Signer,
    H: Hasher,
    S: Supervisor<Index = View, PublicKey = C::PublicKey>,
> {
    context: E,
    crypto: C,
    supervisor: S,
    _hasher: PhantomData<H>,

    namespace: Vec<u8>,
}

impl<E: Spawner, C: Signer, H: Hasher, S: Supervisor<Index = View, PublicKey = C::PublicKey>>
    Nuller<E, C, H, S>
{
    pub fn new(context: E, cfg: Config<C, S>) -> Self {
        Self {
            context,
            crypto: cfg.crypto,
            supervisor: cfg.supervisor,
            _hasher: PhantomData,

            namespace: cfg.namespace,
        }
    }

    pub fn start(mut self, voter_network: (impl Sender, impl Receiver)) -> Handle<()> {
        self.context.spawn_ref()(self.run(voter_network))
    }

    async fn run(mut self, voter_network: (impl Sender, impl Receiver)) {
        let (mut sender, mut receiver) = voter_network;
        while let Ok((s, msg)) = receiver.recv().await {
            // Parse message
            let msg = match Voter::<C::Signature, H::Digest>::decode_cfg(msg, &usize::MAX) {
                Ok(msg) => msg,
                Err(err) => {
                    debug!(?err, sender = ?s, "failed to decode message");
                    continue;
                }
            };
            let view = msg.view();

            // Process message
            match msg {
                Voter::Notarize(notarize) => {
                    // Get our index
                    let public_key_index = self
                        .supervisor
                        .is_participant(view, &self.crypto.public_key())
                        .unwrap();

                    // Nullify
                    let msg =
                        Nullify::sign(&self.namespace, &mut self.crypto, public_key_index, view);
                    let msg = Voter::Nullify::<C::Signature, H::Digest>(msg)
                        .encode()
                        .into();
                    sender.send(Recipients::All, msg, true).await.unwrap();

                    // Finalize digest
                    let msg = Finalize::sign(
                        &self.namespace,
                        &mut self.crypto,
                        public_key_index,
                        notarize.proposal,
                    );
                    let msg = Voter::Finalize(msg).encode().into();
                    sender.send(Recipients::All, msg, true).await.unwrap();
                }
                _ => continue,
            }
        }
    }
}