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|
//! Code for running websocket related functions on the web server.
//!
//! This includes the messaging system as a whole.
use std::sync::Arc;
use axum::extract::ws::{Message, WebSocket};
use futures::{
stream::{SplitSink, SplitStream},
SinkExt, StreamExt,
};
use messenger_common::{
client::MessageType as ClientMessageType,
server::{MessageType, UserMessage},
};
use thiserror::Error;
use tokio::sync::{broadcast::Receiver, Mutex};
use crate::{
app::State as AppState,
message::{self, deserialize, Server},
};
/// Represents an error that can occur during a session.
#[derive(Debug, Error)]
pub enum Error {
/// An error with a Axum
#[error("an error occurred while attempting to interact with Axum")]
Axum(#[from] axum::Error),
/// An error with serde_json
#[error("an error occurred while ser/deserializing data with serde_json")]
SerdeJson(#[from] serde_json::Error),
}
/// Represents a singular session for a user. Handles sending and receiving
/// messages for this session.
#[derive(Debug)]
pub struct Session {
/// Receiving component of the WebSocket split.
receiver: Mutex<SplitStream<WebSocket>>,
/// Sending component of the WebSocket split.
sender: Mutex<SplitSink<WebSocket, Message>>,
/// Receiver from the apps state.
state_rx: Mutex<Receiver<String>>,
/// The username associated with this session.
username: String,
}
impl Session {
/// Constructs a new instance of [`Session`].
#[must_use]
pub fn new(
receiver: SplitStream<WebSocket>,
sender: SplitSink<WebSocket, Message>,
state_rx: Receiver<String>,
username: String,
) -> Self {
Self {
receiver: Mutex::new(receiver),
sender: Mutex::new(sender),
state_rx: Mutex::new(state_rx),
username,
}
}
/// Feeds the last 100 messages to a singular sender, differentiated by the
/// `WebSocket` sender.
pub async fn feed_message_history(&self, state: &Arc<crate::app::State>) {
// Iterate through the message history and feed it to the sender
for message in &*state.message_history.lock().await {
if self
.sender
.lock()
.await
.feed(Message::Text(message.clone()))
.await
.is_err()
{
break;
}
}
}
/// Feeds a list of online users to a singular sender, differentiated by the
/// `WebSocket` sender.
pub async fn feed_online_users(&self, state: &Arc<crate::app::State>) -> Result<(), Error> {
self.sender
.lock()
.await
.feed(Message::Text(serde_json::to_string(
&MessageType::OnlineUsers(state.user_set.lock().await.clone()),
)?))
.await?;
Ok(())
}
/// Receives messages for this session. For use inside a tokio select
/// receive task.
pub async fn receive(&self, state: &Arc<AppState>) {
while let Some(Ok(Message::Text(text))) = self.receiver.lock().await.next().await {
let result = match deserialize(&text) {
Ok(ClientMessageType::UserMessage(content)) => {
// Handle the possibility of a timestamp being unable to be created when a
// message is bring processed
let Ok(timestamp) = time::OffsetDateTime::now_local() else {
tracing::error!("could not create an OffsetDateTime for received message");
let mut lock = self.sender.lock().await;
// Report to the client that their message could not be processed
message::send_error(
&mut lock,
messenger_common::server::Error::CannotProcess,
)
.await;
// Drop the lock early
drop(lock);
// Skip to the next message.
continue;
};
let message: MessageType =
UserMessage::new(content, self.username.clone(), timestamp).into();
Some(message)
}
Ok(_) | Err(_) => {
let mut lock = self.sender.lock().await;
// Messages outside of type UserMessage are unexpected, and should be
// reported
message::send_error(&mut lock, messenger_common::server::Error::InvalidMessage)
.await;
drop(lock);
None
}
};
if let Some(message) = result {
message.send(&state.tx);
if let Err(error) = message.append_to_history(state).await {
tracing::error!(
"error encountered when appending a message to history: {error}"
);
}
}
}
}
/// Processes a send operation for this session.
pub async fn send(&self) {
let mut lock = self.state_rx.lock().await;
while let Ok(msg) = lock.recv().await {
// In any websocket error, break loop.
if self
.sender
.lock()
.await
.send(Message::Text(msg))
.await
.is_err()
{
break;
}
}
}
/// Transmits a copy of the last 100 messages and a list of online users to
/// the user.
pub async fn transmit_initial_data(&self, state: &Arc<crate::app::State>) -> Result<(), Error> {
self.feed_message_history(state).await;
self.feed_online_users(state).await?;
self.sender.lock().await.flush().await?;
Ok(())
}
/// Retrieves a copy to the username associated with this session.
pub const fn username(&self) -> &String {
&self.username
}
}
|