feat(asb): Take ongoing swaps into consideration when crafting quote

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- ASB: The maker will take Monero funds needed for ongoing swaps into consideration when making a quote. A warning will be displayed if the Monero funds do not cover all ongoing swaps.
+
 ## [1.0.0-rc.17] - 2025-04-18
 
 - GUI: The user will now be asked to approve the swap offer again before the Bitcoin lock transaction is published. Makers should take care to only assume a swap has been accepted by the taker if the Bitcoin lock transaction is detected (`Advancing state state=bitcoin lock transaction in mempool ...`). Swaps that have been safely aborted will not be displayed in the GUI anymore.
@@ -30,7 +32,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [1.0.0-rc.12] - 2025-01-14
 
 - GUI: Fixed a bug where the CLI wasn't passed the correct Monero node.
--
 
 ## [1.0.0-rc.11] - 2024-12-22
 

Cargo.toml

@@ -1,6 +1,6 @@
 [workspace]
 resolver = "2"
-members = [ "monero-harness", "monero-rpc", "swap", "monero-wallet", "src-tauri" ]
+members = [ "monero-harness", "monero-rpc", "swap", "monero-wallet", "src-tauri", "monero-sys" ]
 
 [patch.crates-io]
 # patch until new release https://github.com/thomaseizinger/rust-jsonrpc-client/pull/51

dev-docs/asb/README.md

@@ -31,7 +31,9 @@ Consider joining the designated [Matrix chat](https://matrix.to/#/%23unstoppable
 
 ### Using Docker
 
-Running the ASB and its required services (Bitcoin node, Monero node, wallet RPC) can be complex to set up manually. We provide a Docker Compose solution that handles all of this automatically. See our [docker-compose repository](https://github.com/UnstoppableSwap/asb-docker-compose) for setup instructions and configuration details.
+Running the ASB and its required services (Bitcoin node, Monero node, wallet RPC) can be complex to set up manually. 
+We provide a Docker Compose solution that handles all of this automatically. 
+See our [docker-compose repository](https://github.com/UnstoppableSwap/asb-docker-compose) for setup instructions and configuration details.
 
 ## ASB Details
 

swap/src/asb/event_loop.rs

@@ -1,5 +1,5 @@
 use crate::asb::{Behaviour, OutEvent, Rate};
-use crate::monero::Amount;
+use crate::monero::{Amount, MONERO_FEE};
 use crate::network::cooperative_xmr_redeem_after_punish::CooperativeXmrRedeemRejectReason;
 use crate::network::cooperative_xmr_redeem_after_punish::Response::{Fullfilled, Rejected};
 use crate::network::quote::BidQuote;
@@ -511,44 +511,71 @@ where
         result
     }
 
+    /// Returns the unreserved Monero balance
+    /// Meaning the Monero balance that is not reserved for ongoing swaps and can be used for new swaps
+    async fn unreserved_monero_balance(&self) -> Result<Amount, Arc<anyhow::Error>> {
+        /// This is how long we maximally wait to get access to the wallet
+        const MAX_WAIT_DURATION: Duration = Duration::from_secs(60);
+
+        let balance = timeout(MAX_WAIT_DURATION, self.monero_wallet.lock())
+            .await
+            .context("Timeout while waiting for lock on monero wallet while making quote")?
+            .get_balance()
+            .await
+            .map_err(|e| Arc::new(e.context("Failed to get Monero balance")))?;
+
+        let balance = Amount::from_piconero(balance.unlocked_balance);
+
+        // From our full balance we need to subtract any Monero that is 'reserved' for ongoing swaps
+        // Those swaps where the Bitcoin has been locked (may be unconfirmed or confirmed) but we haven't locked the Monero yet
+        // This is a naive approach because:
+        // - Suppose we have two UTXOs each 5 XMR
+        // - We have a pending swap for 6 XMR
+        // The code will assume we only have reserved 6 XMR but once we lock the 6 XMR our two outputs will be spent
+        // and it'll take 10 blocks before we can use our new output (4 XMR change) again
+        let reserved: Amount = self
+            .db
+            .all()
+            .await?
+            .iter()
+            .filter_map(|(_, state)| match state {
+                State::Alice(AliceState::BtcLockTransactionSeen { state3 })
+                | State::Alice(AliceState::BtcLocked { state3 }) => Some(state3.xmr + MONERO_FEE),
+                _ => None,
+            })
+            .fold(Amount::ZERO, |acc, amount| acc + amount);
+
+        let free_monero_balance = balance.checked_sub(reserved).unwrap_or(Amount::ZERO);
+
+        Ok(free_monero_balance)
+    }
+
     /// Computes a quote and returns the result wrapped in Arcs.
     async fn make_quote(
         &mut self,
         min_buy: bitcoin::Amount,
         max_buy: bitcoin::Amount,
     ) -> Result<Arc<BidQuote>, Arc<anyhow::Error>> {
-        /// This is how long we maximally wait for the wallet lock
-        /// -- else the quote will be out of date and we will return
-        /// an error.
-        const MAX_WAIT_DURATION: Duration = Duration::from_secs(60);
-
         let ask_price = self
             .latest_rate
             .latest_rate()
             .map_err(|e| Arc::new(anyhow!(e).context("Failed to get latest rate")))?
             .ask()
             .map_err(|e| Arc::new(e.context("Failed to compute asking price")))?;
 
-        let balance = timeout(MAX_WAIT_DURATION, self.monero_wallet.lock())
-            .await
-            .context("Timeout while waiting for lock on monero wallet while making quote")?
-            .get_balance()
-            .await
-            .map_err(|e| Arc::new(e.context("Failed to get Monero balance")))?;
-        let xmr_balance = Amount::from_piconero(balance.unlocked_balance);
-
-        let max_bitcoin_for_monero =
-            xmr_balance
-                .max_bitcoin_for_price(ask_price)
-                .ok_or_else(|| {
-                    Arc::new(anyhow!(
-                        "Bitcoin price ({}) x Monero ({}) overflow",
-                        ask_price,
-                        xmr_balance
-                    ))
-                })?;
-
-        tracing::trace!(%ask_price, %xmr_balance, %max_bitcoin_for_monero, "Computed quote");
+        let unreserved_xmr_balance = self.unreserved_monero_balance().await?;
+
+        let max_bitcoin_for_monero = unreserved_xmr_balance
+            .max_bitcoin_for_price(ask_price)
+            .ok_or_else(|| {
+                Arc::new(anyhow!(
+                    "Bitcoin price ({}) x Monero ({}) overflow",
+                    ask_price,
+                    unreserved_xmr_balance
+                ))
+            })?;
+
+        tracing::trace!(%ask_price, %unreserved_xmr_balance, %max_bitcoin_for_monero, "Computed quote");
 
         if min_buy > max_bitcoin_for_monero {
             tracing::trace!(

swap/src/monero.rs

@@ -9,7 +9,7 @@ pub use wallet::Wallet;
 pub use wallet_rpc::{WalletRpc, WalletRpcProcess};
 
 use crate::bitcoin;
-use anyhow::Result;
+use anyhow::{bail, Result};
 use rand::{CryptoRng, RngCore};
 use rust_decimal::prelude::*;
 use rust_decimal::Decimal;
@@ -164,6 +164,15 @@ impl Amount {
             .ok_or_else(|| OverflowError(amount.to_string()))?;
         Ok(Amount(piconeros))
     }
+
+    /// Subtract but throw an error on underflow.
+    pub fn checked_sub(self, rhs: Amount) -> Result<Self> {
+        if self.0 < rhs.0 {
+            bail!("checked sub would underflow");
+        }
+
+        Ok(Amount::from_piconero(self.0 - rhs.0))
+    }
 }
 
 impl Add for Amount {
@@ -174,7 +183,7 @@ impl Add for Amount {
     }
 }
 
-impl Sub for Amount {
+impl Sub<Amount> for Amount {
     type Output = Amount;
 
     fn sub(self, rhs: Self) -> Self::Output {