Prototype minting circuits for token contracts

src/blockchain/error.rs

@@ -121,4 +121,6 @@ pub enum BlockchainError {
     ValidatorProofNotGiven,
     #[error("epoch randomness can only be changed with vrf-proofs on 0th attempt")]
     RandomnessChangeNotPermitted,
+    #[error("contract is not a token")]
+    ContractNotToken,
 }

src/blockchain/ops/apply_tx/update_contract/mint.rs

@@ -0,0 +1,40 @@
+use super::*;
+
+pub fn mint<K: KvStore>(
+    chain: &mut KvStoreChain<K>,
+    contract_id: &ContractId,
+    contract: &zk::ZkContract,
+    function_id: &u32,
+    amount: &Amount,
+    executor_fees: &mut Vec<Money>,
+) -> Result<(zk::ZkVerifierKey, zk::ZkCompressedState), BlockchainError> {
+    if let Some(token) = &contract.token {
+        /*let mut bal = chain.get_contract_balance(contract_id.clone(), *token_id)?;
+        if bal + *amount < bal || token.token.supply + *amount < token.token.supply {
+            return Err(BlockchainError::TokenSupplyOverflow);
+        }
+        bal += *amount;
+        token.supply += *amount;
+        chain
+            .database
+            .update(&[WriteOp::Put(keys::token(token_id), (&token).into())])?;
+        chain.database.update(&[WriteOp::Put(
+            keys::account_balance(&tx_src, *token_id),
+            bal.into(),
+        )])?;*/
+
+        let func = token
+            .mint_functions
+            .get(*function_id as usize)
+            .ok_or(BlockchainError::ContractFunctionNotFound)?;
+        let circuit = &func.verifier_key;
+        let mut state_builder = zk::ZkStateBuilder::<CoreZkHasher>::new(zk::ZkStateModel::Scalar);
+        state_builder.batch_set(&zk::ZkDeltaPairs(
+            [(zk::ZkDataLocator(vec![]), Some((*amount).into()))].into(),
+        ))?;
+        let aux_data = state_builder.compress()?;
+        Ok((circuit.clone(), aux_data))
+    } else {
+        Err(BlockchainError::ContractNotToken)
+    }
+}

src/blockchain/ops/apply_tx/update_contract/mod.rs

@@ -1,5 +1,6 @@
 mod deposit;
 mod function_call;
+mod mint;
 mod withdraw;
 
 use super::*;
@@ -83,7 +84,15 @@ pub fn update_contract<K: KvStore>(
                 (circuit, aux_data)
             }
             ContractUpdateData::Mint { amount } => {
-                unimplemented!();
+                let (circuit, aux_data) = mint::mint(
+                    chain,
+                    &contract_id,
+                    &contract,
+                    &update.circuit_id,
+                    amount,
+                    &mut executor_fees,
+                )?;
+                (circuit, aux_data)
             }
         };