pools: Update smart contract balance after UTXO transfer

If the UTXO transfer from contract to P2PK or contract succeeds,
zero the balance of the smart contract as the contract no longer
holds any funds.

pallets/pp/src/lib.rs

@@ -144,7 +144,12 @@ fn send_p2pk_tx<T: Config>(
     ensure!(fund_info.funds >= value, "Caller doesn't have enough funds");
     let outpoints = fund_info.utxos.iter().map(|x| x.0).collect::<Vec<H256>>();
 
-    T::Utxo::submit_c2pk_tx(caller, dest, value, &outpoints)
+    T::Utxo::submit_c2pk_tx(caller, dest, value, &outpoints).map(|_| {
+        <ContractBalances<T>>::mutate(&caller, |info| {
+            info.as_mut().unwrap().utxos = Vec::new();
+            info.as_mut().unwrap().funds = 0;
+        });
+    })
 }
 
 /// Create Contract-to-Contract transfer that allows smart contracts to
@@ -169,7 +174,12 @@ fn send_c2c_tx<T: Config>(
     ))?;
     let outpoints = fund_info.utxos.iter().map(|x| x.0).collect::<Vec<H256>>();
 
-    T::Utxo::submit_c2c_tx(caller, dest, fund_info.funds, data, &outpoints)
+    T::Utxo::submit_c2c_tx(caller, dest, fund_info.funds, data, &outpoints).map(|_| {
+        <ContractBalances<T>>::mutate(&caller, |info| {
+            info.as_mut().unwrap().utxos = Vec::new();
+            info.as_mut().unwrap().funds = 0;
+        });
+    })
 }
 
 impl<T: Config> ProgrammablePoolApi for Pallet<T>