aeronet_replicon 0.18.0

//! Client-side [`bevy_replicon`] support.

use {
    crate::convert,
    aeronet_io::{Session, SessionEndpoint, connection::Disconnect},
    aeronet_transport::{
        AeronetTransportPlugin, Transport, TransportSystems,
        sampling::{SessionSamplingPlugin, SessionStats, SessionStatsSampling},
    },
    bevy_app::prelude::*,
    bevy_ecs::prelude::*,
    bevy_platform::time::Instant,
    bevy_reflect::prelude::*,
    bevy_replicon::prelude::*,
    bevy_state::state::NextState,
    core::{num::Saturating, time::Duration},
    log::{trace, warn},
};

/// Provides a [`bevy_replicon`] client backend using [`Session`]s for
/// communication.
///
/// To make a [`Session`] be used by [`bevy_replicon`], add the
/// [`AeronetRepliconClient`] component.
pub struct AeronetRepliconClientPlugin;

impl Plugin for AeronetRepliconClientPlugin {
    fn build(&self, app: &mut App) {
        if !app.is_plugin_added::<AeronetTransportPlugin>() {
            app.add_plugins(AeronetTransportPlugin);
        }
        if !app.is_plugin_added::<SessionSamplingPlugin>() {
            app.add_plugins(SessionSamplingPlugin);
        }

        app.register_type::<AeronetRepliconClient>()
            .configure_sets(
                PreUpdate,
                (
                    TransportSystems::Poll,
                    ClientTransportSystems::Poll,
                    ClientSystems::ReceivePackets,
                )
                    .chain(),
            )
            .configure_sets(
                PostUpdate,
                (
                    ClientSystems::SendPackets,
                    ClientTransportSystems::Flush,
                    TransportSystems::Flush,
                )
                    .chain(),
            )
            .add_systems(
                PreUpdate,
                (update_state, poll)
                    .chain()
                    .in_set(ClientTransportSystems::Poll)
                    .run_if(resource_exists::<ClientMessages>),
            )
            .add_systems(
                PostUpdate,
                flush
                    .in_set(ClientTransportSystems::Flush)
                    .run_if(resource_exists::<ClientMessages>),
            )
            .add_observer(on_client_connected);
    }
}

/// Sets for systems which provide communication between [`bevy_replicon`] and
/// [`Session`]s.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, SystemSet)]
pub enum ClientTransportSystems {
    /// Passing incoming messages into [`bevy_replicon`].
    ///
    /// # Ordering
    ///
    /// - [`TransportSystems::Poll`]
    /// - **[`ClientTransportSystems::Poll`]**
    /// - [`ClientSystems::ReceivePackets`]
    Poll,
    /// Passing outgoing [`bevy_replicon`] packets to the transport layer.
    ///
    /// # Ordering
    ///
    /// - [`ClientSystems::SendPackets`]
    /// - **[`ClientTransportSystems::Flush`]**
    /// - [`TransportSystems::Flush`]
    Flush,
}

/// Marker component for a [`Session`] which is used as the messaging backend
/// for a Replicon client.
///
/// Sessions with this component automatically get [`Transport`].
///
/// Any session entity with this component will be used for:
/// - receiving messages
///   - on the Replicon side, you can't differentiate which session received
///     which message
/// - sending messages
///   - all outgoing Replicon messages are cloned and sent to all sessions
/// - determining connected status
///   - if at least 1 session has both [`SessionEndpoint`] and [`Session`],
///     [`ClientState`] is [`ClientState::Connected`]
///   - if at least 1 session has [`SessionEndpoint`], [`ClientState`] is
///     [`ClientState::Connecting`]
///   - else, [`ClientState::Disconnected`]
///
/// Since [`ClientState`] is a state, there can only be up to one client at a
/// time in the app, and you can only connect to one "logical" server at a time
/// (that is, the server which holds the actual app state). Therefore, your app
/// should only have one [`AeronetRepliconClient`].
#[derive(Debug, Clone, Copy, Default, Component, Reflect)]
#[reflect(Component)]
pub struct AeronetRepliconClient;

fn on_client_connected(
    trigger: On<Add, Session>,
    mut commands: Commands,
    clients: Query<&Session, With<AeronetRepliconClient>>,
    channels: Res<RepliconChannels>,
) {
    let target = trigger.event_target();
    let Ok(session) = clients.get(target) else {
        return;
    };

    let rx_lanes = channels
        .server_channels()
        .iter()
        .map(|channel| convert::to_lane_kind(*channel));
    let tx_lanes = channels
        .client_channels()
        .iter()
        .map(|channel| convert::to_lane_kind(*channel));
    let now = Instant::now();

    let transport = match Transport::new(session, rx_lanes, tx_lanes, now) {
        Ok(transport) => transport,
        Err(err) => {
            warn!("Failed to create transport for {target}: {err:?}");
            commands.trigger(Disconnect::new(target, "failed to create transport"));
            return;
        }
    };

    commands.entity(target).insert(transport);
}

fn update_state(
    mut client_stats: ResMut<ClientStats>,
    mut next_client_state: ResMut<NextState<ClientState>>,
    clients: Query<
        (Option<&Session>, Option<&Transport>, Option<&SessionStats>),
        (With<SessionEndpoint>, With<AeronetRepliconClient>),
    >,
    sampling: Res<SessionStatsSampling>,
) {
    let (
        mut endpoint_exists,
        mut num_connected,
        mut sum_rtt,
        mut sum_packet_loss,
        mut sum_bytes_recv,
        mut sum_bytes_sent,
    ) = (
        false,
        Saturating(0usize),
        Duration::ZERO,
        0.0,
        Saturating(0usize),
        Saturating(0usize),
    );

    for (session, transport, stats) in &clients {
        endpoint_exists = true;

        let (Some(_), Some(_), Some(stats)) = (session, transport, stats) else {
            continue;
        };
        let stats = stats.last().copied().unwrap_or_default();

        num_connected += 1;
        sum_rtt += stats.msg_rtt;
        sum_packet_loss += stats.loss;
        sum_bytes_recv += stats.packets_delta.bytes_recv;
        sum_bytes_sent += stats.packets_delta.bytes_sent;
    }

    let (next_status, rtt, packet_loss, received_bps, sent_bps) = if num_connected.0 > 0 {
        #[expect(clippy::cast_precision_loss, reason = "precision loss is acceptable")]
        let num_connected = num_connected.0 as f64;
        #[expect(clippy::cast_precision_loss, reason = "precision loss is acceptable")]
        let (received_bps, sent_bps) = (
            (sum_bytes_recv.0 as f64 / num_connected) * sampling.rate(),
            (sum_bytes_sent.0 as f64 / num_connected) * sampling.rate(),
        );

        (
            ClientState::Connected,
            sum_rtt.as_secs_f64() / num_connected,
            sum_packet_loss / num_connected,
            received_bps,
            sent_bps,
        )
    } else {
        let status = if endpoint_exists {
            ClientState::Connecting
        } else {
            ClientState::Disconnected
        };
        (status, 0.0, 0.0, 0.0, 0.0)
    };

    next_client_state.set(next_status);
    client_stats.rtt = rtt;
    client_stats.packet_loss = packet_loss;
    client_stats.received_bps = received_bps;
    client_stats.sent_bps = sent_bps;
}

fn poll(
    mut client_msgs: ResMut<ClientMessages>,
    mut clients: Query<(Entity, &mut Transport), With<AeronetRepliconClient>>,
) {
    for (client, mut transport) in &mut clients {
        let mut msgs_recv = Saturating(0usize);
        let mut bytes_recv = Saturating(0usize);
        for msg in transport.recv.msgs.drain() {
            msgs_recv += 1;
            bytes_recv += msg.payload.len();

            let channel_id = convert::to_channel_id(msg.lane);
            client_msgs.insert_received(channel_id, msg.payload);
        }
        if msgs_recv.0 > 0 || bytes_recv.0 > 0 {
            trace!(
                "Client {client} received {msgs_recv} messages ({bytes_recv} bytes) from server"
            );
        }

        for _ in transport.recv.acks.drain() {
            // we don't use the acks for anything
        }
    }
}

fn flush(
    mut client_msgs: ResMut<ClientMessages>,
    mut clients: Query<&mut Transport, With<AeronetRepliconClient>>,
) {
    let now = Instant::now();
    for (channel_id, msg) in client_msgs.drain_sent() {
        let Some(lane_index) = convert::to_lane_index(channel_id) else {
            warn!("Channel {channel_id} is too large to convert to a lane index");
            continue;
        };

        trace!(
            "Sent 1 message ({} bytes) along all clients to all servers",
            msg.len()
        );
        for mut transport in &mut clients {
            _ = transport.send.push(lane_index, msg.clone(), now);
        }
    }
}