Use log filtering instead of getting latest root

internal/config/poll_verifier.go

@@ -98,18 +98,22 @@ func (v *PollVerifier) VerifyProof(proof zkptypes.ZKProof, proposalID, proposalE
 		return ErrInvalidProposalEventID
 	}
 
-	proposalSMTAddress := proposalInfo.ProposalSMT
-	proposalSMTCaller, err := proposalsmt.NewProposalSMTCaller(proposalSMTAddress, v.RPC)
+	root := decimalTo32Bytes(proof.PubSignals[PollNullifierTreeRoot])
+	if root == [32]byte{} {
+		return ErrInvalidRoot
+	}
+
+	proposalSMTCaller, err := proposalsmt.NewProposalSMTFilterer(proposalInfo.ProposalSMT, v.RPC)
 	if err != nil {
 		return fmt.Errorf("failed to create proposal smt caller: %w", err)
 	}
 
-	root, err := proposalSMTCaller.GetRoot(nil)
+	it, err := proposalSMTCaller.FilterRootUpdated(nil, [][32]byte{root})
 	if err != nil {
 		return fmt.Errorf("failed to get root: %w", err)
 	}
 
-	if new(big.Int).SetBytes(root[:]).String() != proof.PubSignals[PollNullifierTreeRoot] {
+	if ok := it.Next(); !ok {
 		return ErrInvalidRoot
 	}
 
@@ -123,3 +127,15 @@ func (v *PollVerifier) VerifyProof(proof zkptypes.ZKProof, proposalID, proposalE
 
 	return nil
 }
+
+func decimalTo32Bytes(root string) [32]byte {
+	b, ok := new(big.Int).SetString(root, 10)
+	if !ok {
+		return [32]byte{}
+	}
+
+	var bytes [32]byte
+	b.FillBytes(bytes[:])
+
+	return bytes
+}