analyzer/runtime: enable balance tracking for ERC-721

analyzer/runtime/evm/client.go

@@ -255,6 +255,13 @@ func EVMDownloadTokenBalance(ctx context.Context, logger *log.Logger, source nod
 		}
 		return balance, nil
 
+	case EVMTokenTypeERC721:
+		balance, err := evmDownloadTokenBalanceERC721(ctx, logger, source, round, tokenEthAddr, accountEthAddr)
+		if err != nil {
+			return nil, fmt.Errorf("download token balance ERC-721: %w", err)
+		}
+		return balance, nil
+
 	// todo: add support for other token types
 	// see https://github.com/oasisprotocol/oasis-indexer/issues/225
 

analyzer/runtime/evm/erc721.go

@@ -2,8 +2,10 @@ package evm
 
 import (
 	"context"
+	"encoding/hex"
 	"fmt"
 
+	ethCommon "github.com/ethereum/go-ethereum/common"
 	"github.com/oasisprotocol/oasis-core/go/common/errors"
 
 	"github.com/oasisprotocol/oasis-indexer/analyzer/evmabi"
@@ -59,3 +61,18 @@ func evmDownloadTokenERC721(ctx context.Context, logger *log.Logger, source node
 	tokenData.EVMTokenMutableData = mutable
 	return &tokenData, nil
 }
+
+func evmDownloadTokenBalanceERC721(ctx context.Context, logger *log.Logger, source nodeapi.RuntimeApiLite, round uint64, tokenEthAddr []byte, accountEthAddr []byte) (*EVMTokenBalanceData, error) {
+	var balanceData EVMTokenBalanceData
+	accountECAddr := ethCommon.BytesToAddress(accountEthAddr)
+	if err := evmCallWithABI(ctx, source, round, tokenEthAddr, evmabi.ERC721, &balanceData.Balance, "balanceOf", accountECAddr); err != nil {
+		if !errors.Is(err, EVMDeterministicError{}) {
+			return nil, fmt.Errorf("calling balanceOf: %w", err)
+		}
+		logDeterministicError(logger, round, tokenEthAddr, "ERC721", "balanceOf", err,
+			"account_eth_addr_hex", hex.EncodeToString(accountEthAddr),
+		)
+		return nil, nil
+	}
+	return &balanceData, nil
+}

analyzer/runtime/extract.go

@@ -739,13 +739,15 @@ func extractEvents(blockData *BlockData, relatedAccountAddresses map[apiTypes.Ad
 							return fmt.Errorf("from: %w", err2)
 						}
 						eventData.RelatedAddresses[fromAddr] = true
+						registerTokenDecrease(blockData.TokenBalanceChanges, eventAddr, fromAddr, big.NewInt(1))
 					}
 					if !toZero {
 						toAddr, err2 := registerRelatedEthAddress(blockData.AddressPreimages, relatedAccountAddresses, toEthAddr)
 						if err2 != nil {
 							return fmt.Errorf("to: %w", err2)
 						}
 						eventData.RelatedAddresses[toAddr] = true
+						registerTokenIncrease(blockData.TokenBalanceChanges, eventAddr, toAddr, big.NewInt(1))
 					}
 					// todo: reckon ownership
 					if _, ok := blockData.PossibleTokens[eventAddr]; !ok {