Quote websocket

Instead of just sending a price we properly create a bid quote analogue to the libp2p quote protocol.
The service websocket sends `BidQuote`s or an Error.
The `BidQuote` sent reuses the struct from the libp2p quote protocol.

swap/src/asb.rs

@@ -1,6 +1,6 @@
 pub mod command;
 pub mod config;
-pub mod price_websocket;
+pub mod quote_websocket;
 mod rate;
 pub mod tracing;
 

swap/src/asb/price_websocket.rs

@@ -1,28 +0,0 @@
-use crate::kraken::PriceUpdates;
-use anyhow::Context;
-use futures::{stream, StreamExt, TryStreamExt};
-use warp::ws::{Message, WebSocket};
-
-pub async fn latest_rate(ws: WebSocket, subscription: PriceUpdates) {
-    let stream = stream::try_unfold(subscription.inner, |mut receiver| async move {
-        // todo print error message but don't forward it to the user and don't panic
-        receiver
-            .changed()
-            .await
-            .context("failed to receive latest rate update")
-            .expect("Should not fail :)");
-
-        let latest_rate = receiver.borrow().clone().expect("Should work");
-
-        // TODO: Proper definition of what to send over the wire
-        // TODO: Properly calculate the actual rate (using spread) and add min and max
-        // amounts tradeable
-        let msg = Message::text(serde_json::to_string(&latest_rate).expect("to serialize"));
-
-        Ok(Some((msg, receiver)))
-    })
-    .into_stream();
-
-    let (ws_tx, mut _ws_rx) = ws.split();
-    tokio::task::spawn(stream.forward(ws_tx));
-}

swap/src/asb/quote_websocket.rs

@@ -0,0 +1,88 @@
+use crate::asb::Rate;
+use crate::kraken::PriceUpdates;
+use crate::network::quote::BidQuote;
+use anyhow::Context;
+use futures::{stream, StreamExt, TryStreamExt};
+use rust_decimal::Decimal;
+use serde::Serialize;
+use warp::ws::{Message, WebSocket};
+use warp::Filter;
+
+pub async fn setup_quote_websocket(
+    price_updates: PriceUpdates,
+    spread: Decimal,
+    min: bitcoin::Amount,
+    max: bitcoin::Amount,
+) {
+    let latest_quote = warp::get()
+        .and(warp::path!("api" / "quote" / "xmr-btc"))
+        .and(warp::ws())
+        .map(move |ws: warp::ws::Ws| {
+            let price_updates = price_updates.clone();
+            tracing::info!("New quote websocket connection");
+            ws.on_upgrade(move |socket| {
+                quote_stream(socket, price_updates, spread, min, max)
+            })
+        });
+    tokio::spawn(async move {
+        warp::serve(latest_quote).run(([0, 0, 0, 0], 3030)).await;
+    });
+}
+
+async fn quote_stream(
+    ws: WebSocket,
+    subscription: PriceUpdates,
+    spread: Decimal,
+    min: bitcoin::Amount,
+    max: bitcoin::Amount,
+) {
+    let stream = stream::try_unfold(subscription.inner, move |mut receiver| async move {
+        if let Err(e) = receiver.changed().await {
+            tracing::error!(
+                "Failed to initialize price update stream for quote websocket: {:#}",
+                e
+            );
+        }
+
+        let quote = match receiver.borrow().clone() {
+            Ok(latest_price_update) => match Rate::new(latest_price_update.ask, spread).ask() {
+                Ok(amount) => WebsocketBidQuote::Quote(BidQuote {
+                    price: amount,
+                    min_quantity: min,
+                    max_quantity: max,
+                }),
+                Err(e) => {
+                    tracing::error!("Failed to create quote for quote websocket: {:#}", e);
+                    WebsocketBidQuote::Error(Error::BidQuoteError)
+                }
+            },
+            Err(e) => {
+                tracing::error!(
+                    "Failed to fetch latest price update for quote websocket: {:#}",
+                    e
+                );
+                WebsocketBidQuote::Error(Error::PriceUpdateError)
+            }
+        };
+
+        let msg = Message::text(serde_json::to_string(&quote).expect("quote to serialize"));
+
+        Ok(Some((msg, receiver)))
+    })
+    .into_stream();
+
+    let (ws_tx, mut _ws_rx) = ws.split();
+    tokio::task::spawn(stream.forward(ws_tx));
+}
+
+#[derive(Serialize, Debug, Clone)]
+enum WebsocketBidQuote {
+    Quote(BidQuote),
+    Error(Error),
+}
+
+#[derive(Clone, Debug, Serialize)]
+enum Error {
+    PriceUpdateError,
+    BidQuoteError,
+}

swap/src/bin/asb.rs

@@ -26,9 +26,8 @@ use swap::asb::command::{parse_args, Arguments, Command};
 use swap::asb::config::{
     initial_setup, query_user_for_initial_config, read_config, Config, ConfigNotInitialized,
 };
-use swap::asb::price_websocket::latest_rate;
+use swap::asb::quote_websocket::setup_quote_websocket;
 use swap::database::Database;
-use swap::kraken::PriceUpdates;
 use swap::monero::Amount;
 use swap::network::swarm;
 use swap::protocol::alice;
@@ -39,7 +38,6 @@ use swap::tor::AuthenticatedClient;
 use swap::{asb, bitcoin, kraken, monero, tor};
 use tracing::{debug, info, warn};
 use tracing_subscriber::filter::LevelFilter;
-use warp::Filter;
 
 #[macro_use]
 extern crate prettytable;
@@ -130,7 +128,13 @@ async fn main() -> Result<()> {
 
             let kraken_price_updates = kraken::connect()?;
 
-            setup_price_websocket(kraken_price_updates.clone()).await;
+            setup_quote_websocket(
+                kraken_price_updates.clone(),
+                config.maker.ask_spread,
+                config.maker.min_buy_btc,
+                config.maker.max_buy_btc,
+            )
+            .await;
 
             // setup Tor hidden services
             let tor_client =
@@ -301,20 +305,6 @@ async fn main() -> Result<()> {
     Ok(())
 }
 
-async fn setup_price_websocket(price_updates: PriceUpdates) {
-    let latest_rate = warp::get()
-        .and(warp::path!("api" / "price" / "xmr-btc"))
-        .and(warp::ws())
-        .map(move |ws: warp::ws::Ws| {
-            let price_updates = price_updates.clone();
-            info!("New price websocket connection");
-            ws.on_upgrade(move |socket| latest_rate(socket, price_updates))
-        });
-    tokio::spawn(async move {
-        warp::serve(latest_rate).run(([0, 0, 0, 0], 3030)).await;
-    });
-}
-
 async fn init_bitcoin_wallet(
     config: &Config,
     seed: &Seed,