Add Bob refund execution

swap/src/bob/swap.rs

@@ -10,7 +10,7 @@ use rand::{CryptoRng, RngCore};
 use std::{fmt, sync::Arc};
 use tracing::info;
 use uuid::Uuid;
-use xmr_btc::bob::{self};
+use xmr_btc::bob::{self, Epoch};
 
 // The same data structure is used for swap execution and recovery.
 // This allows for a seamless transition from a failed swap to recovery.
@@ -259,17 +259,41 @@ where
                 )
                 .await
             }
-            BobState::Cancelled(_state) => {
+            BobState::Cancelled(state) => {
                 // Bob has cancelled the swap
-                // If <t2 Bob refunds
-                // if unimplemented!("<t2") {
-                //     // Submit TxRefund
-                //     abort(BobState::BtcRefunded, io).await
-                // } else {
-                //     // Bob failed to refund in time and has been punished
-                //     abort(BobState::Punished, io).await
-                // }
-                Ok(BobState::BtcRefunded)
+                match state.current_epoch(bitcoin_wallet.as_ref()).await? {
+                    // todo: Is this an invalid state?. Should I remove the T0 match branch
+                    Epoch::T0 => panic!("Cancelled before t1??? Something is really wrong"),
+                    Epoch::T1 => {
+                        state.refund_btc(bitcoin_wallet.as_ref()).await?;
+                        run_until(
+                            BobState::BtcRefunded,
+                            is_target_state,
+                            swarm,
+                            db,
+                            bitcoin_wallet,
+                            monero_wallet,
+                            rng,
+                            swap_id,
+                        )
+                        .await
+                    }
+                    Epoch::T2 => {
+                        // todo: If t2 has elapsed should we check whether Alice has punished? If
+                        // not can we still refund?
+                        run_until(
+                            BobState::Punished,
+                            is_target_state,
+                            swarm,
+                            db,
+                            bitcoin_wallet,
+                            monero_wallet,
+                            rng,
+                            swap_id,
+                        )
+                        .await
+                    }
+                }
             }
             BobState::BtcRefunded => Ok(BobState::BtcRefunded),
             BobState::Punished => Ok(BobState::Punished),

xmr-btc/src/bob.rs

@@ -799,11 +799,80 @@ impl State4 {
         t1_timeout.await;
         Ok(())
     }
+
+    pub async fn current_epoch<W>(&self, bitcoin_wallet: &W) -> Result<Epoch>
+    where
+        W: WatchForRawTransaction + TransactionBlockHeight + BlockHeight,
+    {
+        let current_block_height = bitcoin_wallet.block_height().await;
+        let t0 = bitcoin_wallet
+            .transaction_block_height(self.tx_lock.txid())
+            .await;
+        let t1 = t0 + self.refund_timelock;
+        let t2 = t1 + self.punish_timelock;
+
+        match (current_block_height < t1, current_block_height < t2) {
+            (true, _) => Ok(Epoch::T0),
+            (false, true) => Ok(Epoch::T1),
+            (false, false) => Ok(Epoch::T2),
+        }
+    }
+
+    pub async fn refund_btc<W: bitcoin::BroadcastSignedTransaction>(
+        &self,
+        bitcoin_wallet: &W,
+    ) -> Result<()> {
+        let tx_cancel =
+            bitcoin::TxCancel::new(&self.tx_lock, self.refund_timelock, self.A, self.b.public());
+        let tx_refund = bitcoin::TxRefund::new(&tx_cancel, &self.refund_address);
+
+        {
+            let sig_b = self.b.sign(tx_cancel.digest());
+            let sig_a = self.tx_cancel_sig_a.clone();
+
+            let signed_tx_cancel = tx_cancel.clone().add_signatures(
+                &self.tx_lock,
+                (self.A, sig_a),
+                (self.b.public(), sig_b),
+            )?;
+
+            let _ = bitcoin_wallet
+                .broadcast_signed_transaction(signed_tx_cancel)
+                .await?;
+        }
+
+        {
+            let adaptor = Adaptor::<Sha256, Deterministic<Sha256>>::default();
+
+            let sig_b = self.b.sign(tx_refund.digest());
+            let sig_a = adaptor
+                .decrypt_signature(&self.s_b.into_secp256k1(), self.tx_refund_encsig.clone());
+
+            let signed_tx_refund = tx_refund.add_signatures(
+                &tx_cancel.clone(),
+                (self.A, sig_a),
+                (self.b.public(), sig_b),
+            )?;
+
+            let _ = bitcoin_wallet
+                .broadcast_signed_transaction(signed_tx_refund)
+                .await?;
+        }
+        Ok(())
+    }
+
     pub fn tx_lock_id(&self) -> bitcoin::Txid {
         self.tx_lock.txid()
     }
 }
 
+#[derive(Debug, Clone, Copy)]
+pub enum Epoch {
+    T0,
+    T1,
+    T2,
+}
+
 #[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct State5 {
     A: bitcoin::PublicKey,