feat: add AccountBalanceChange proto message (propeller-heads#137)

Author: louise-poole

proto/tycho/evm/v1/common.proto

@@ -55,7 +55,6 @@ enum FinancialType{
   PSM = 3;
 }
 
-
 enum ImplementationType {
   VM = 0;
   CUSTOM = 1;
@@ -128,6 +127,14 @@ message ContractSlot {
   bytes value = 3;
 }
 
+// A struct for following the token balance changes for a contract.
+message AccountBalanceChange {
+  // The address of the ERC20 token whose balance changed.
+  bytes token = 1;
+  // The new balance of the token. Note: it must be a big endian encoded int.
+  bytes balance = 2;
+}
+
 // Changes made to a single contract's state.
 message ContractChange {
   // The contract's address
@@ -140,6 +147,8 @@ message ContractChange {
   repeated ContractSlot slots = 4;
   // Whether this is an update, a creation or a deletion.
   ChangeType change = 5;
+  // The new ERC20 balances of the contract.
+  repeated AccountBalanceChange token_balances = 6;
 }
 
 // Aggregate entities

substreams/crates/tycho-substreams/src/models.rs

@@ -467,6 +467,7 @@ pub struct InterimContractChange {
     code: Vec<u8>,
     slots: HashMap<Vec<u8>, SlotValue>,
     change: ChangeType,
+    token_balances: HashMap<Vec<u8>, Vec<u8>>,
 }
 
 impl InterimContractChange {
@@ -477,6 +478,7 @@ impl InterimContractChange {
             code: vec![],
             slots: Default::default(),
             change: if creation { ChangeType::Creation } else { ChangeType::Update },
+            token_balances: Default::default(),
         }
     }
 
@@ -530,6 +532,11 @@ impl From<InterimContractChange> for Option<ContractChange> {
                 .map(|(slot, value)| ContractSlot { slot, value: value.new_value })
                 .collect(),
             change: value.change.into(),
+            token_balances: value
+                .token_balances
+                .into_iter()
+                .map(|(k, v)| AccountBalanceChange { token: k, balance: v })
+                .collect(),
         };
         if contract_change.is_empty() {
             None