cards/server/src/api.rs

use crate::AppState;
use anyhow::Result;
use axum::{
    extract::{
        ws::{Message, WebSocket},
        ConnectInfo, State, WebSocketUpgrade,
    },
    response::IntoResponse,
};
use futures::stream::SplitSink;
use futures::{SinkExt, StreamExt};
use lib::models::*;
use rand::seq::SliceRandom;
use serde_json::to_string;
use std::{net::SocketAddr, sync::Arc};

pub mod message_handler;
use crate::message_handler::*;

fn motd() -> String {
    to_string::<ChatMessage>(&ChatMessage {
        text: "Greetings from the game server!".to_string(),
    })
    .unwrap()
}

fn server_summary_update(state: &Arc<AppState>) -> String {
    to_string::<ServerStateSummary>(&ServerStateSummary {
        online_users: state.users.lock().unwrap().len(),
        active_games: state.games.lock().unwrap().len(),
    })
    .unwrap()
}

fn chat_update(state: &Arc<AppState>) -> String {
    let mut names = vec![];

    for user in state.users.lock().unwrap().iter() {
        names.push(user.1.name.clone());
    }

    to_string::<ChatUpdate>(&ChatUpdate {
        room: "Lobby".to_string(),
        users: names,
    })
    .unwrap()
}

fn games_update(state: &Arc<AppState>) -> String {
    let mut names = vec![];

    for game in state.games.lock().unwrap().iter() {
        names.push(game.name.clone());
    }

    to_string::<GamesUpdate>(&GamesUpdate { games: names }).unwrap()
}

fn announce_join(state: &Arc<AppState>, addr: &SocketAddr) -> String {
    let msg = format!(
        "{} joined.",
        state.users.lock().unwrap().get(addr).unwrap().name
    );

    tracing::debug!("{}", &msg);

    to_string::<ChatMessage>(&ChatMessage { text: msg }).unwrap()
}

fn generate_new_user(state: &Arc<AppState>) -> User {
    User {
        name: format!(
            "{} {}",
            state.first_names.choose(&mut rand::thread_rng()).unwrap(),
            state.last_names.choose(&mut rand::thread_rng()).unwrap(),
        ),
    }
}

fn client_self_user_update(new_user: &User) -> String {
    to_string::<UserUpdate>(&UserUpdate {
        username: new_user.name.clone(),
    })
    .unwrap()
}

/// Create, Register, and Hydrate new user
async fn handle_new_user(
    sender: &mut SplitSink<WebSocket, Message>,
    state: &Arc<AppState>,
    addr: &SocketAddr,
) -> Result<()> {
    // Create
    let new_user = generate_new_user(state);

    // Notify client of new username
    sender
        .send(Message::Text(client_self_user_update(&new_user)))
        .await?;

    // Register using `addr` as key until something longer lived exists
    state.users.lock().unwrap().insert(*addr, new_user);

    // Hydrate client
    sender.send(Message::Text(chat_update(state))).await?;
    sender.send(Message::Text(motd())).await?;
    sender
        .send(Message::Text(server_summary_update(state)))
        .await?;
    sender.send(Message::Text(games_update(state))).await?;
    state.tx.send(announce_join(state, addr))?;
    state.tx.send(server_summary_update(state))?;
    state.tx.send(chat_update(state))?;

    Ok(())
}

pub async fn on_websocket_connection(stream: WebSocket, state: Arc<AppState>, addr: SocketAddr) {
    // Split channels to send and receive asynchronously.
    let (mut sender, mut receiver) = stream.split();

    handle_new_user(&mut sender, &state, &addr)
        .await
        .expect("Error creating new user!");

    // Subscribe to global broadcast channel
    let mut rx = state.tx.subscribe();

    // Submit new messages from this client to broadcast 
    let mut send_task = tokio::spawn(async move {
        while let Ok(msg) = rx.recv().await {
            if sender.send(Message::Text(msg)).await.is_err() {
                break;
            }
        }
    });

    // Send messages from broadcast down to this client
    let mut recv_task = tokio::spawn(async move {
        while let Some(Ok(message)) = receiver.next().await {
            message_handler(message, &state, addr).await
        }
    });

    // If either task completes then abort the other
    tokio::select! {
        _ = (&mut send_task) => recv_task.abort(),
        _ = (&mut recv_task) => send_task.abort(),
    };
}

pub async fn websocket_connection_handler(
    ws: WebSocketUpgrade,
    // user_agent: Option<TypedHeader<headers::UserAgent>>,
    ConnectInfo(addr): ConnectInfo<SocketAddr>,
    State(state): State<Arc<AppState>>,
) -> impl IntoResponse {
    tracing::debug!("New connection from {}", &addr);
    ws.on_upgrade(move |socket| on_websocket_connection(socket, state, addr))
}