onchain balance getter implementation

api/chain/gateway/internal/service/gateway/commands/wallet/balance.go

@@ -9,7 +9,9 @@ import (
 	"github.com/tech/sendico/pkg/merrors"
 	"github.com/tech/sendico/pkg/mservice"
 	gatewayv1 "github.com/tech/sendico/pkg/proto/chain/gateway/v1"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
 	"go.uber.org/zap"
+	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
 type getWalletBalanceCommand struct {
@@ -34,7 +36,7 @@ func (c *getWalletBalanceCommand) Execute(ctx context.Context, req *gatewayv1.Ge
 		c.deps.Logger.Warn("wallet_ref missing")
 		return gsresponse.InvalidArgument[gatewayv1.GetWalletBalanceResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("wallet_ref is required"))
 	}
-	balance, err := c.deps.Storage.Wallets().GetBalance(ctx, walletRef)
+	wallet, err := c.deps.Storage.Wallets().Get(ctx, walletRef)
 	if err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
 			c.deps.Logger.Warn("not found", zap.String("wallet_ref", walletRef))
@@ -43,5 +45,33 @@ func (c *getWalletBalanceCommand) Execute(ctx context.Context, req *gatewayv1.Ge
 		c.deps.Logger.Warn("storage get failed", zap.Error(err), zap.String("wallet_ref", walletRef))
 		return gsresponse.Auto[gatewayv1.GetWalletBalanceResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
-	return gsresponse.Success(&gatewayv1.GetWalletBalanceResponse{Balance: toProtoWalletBalance(balance)})
+
+	balance, chainErr := onChainWalletBalance(ctx, c.deps, wallet)
+	if chainErr != nil {
+		c.deps.Logger.Warn("on-chain balance fetch failed, falling back to stored balance", zap.Error(chainErr), zap.String("wallet_ref", walletRef))
+		stored, err := c.deps.Storage.Wallets().GetBalance(ctx, walletRef)
+		if err != nil {
+			if errors.Is(err, merrors.ErrNoData) {
+				c.deps.Logger.Warn("stored balance not found", zap.String("wallet_ref", walletRef))
+				return gsresponse.NotFound[gatewayv1.GetWalletBalanceResponse](c.deps.Logger, mservice.ChainGateway, err)
+			}
+			return gsresponse.Auto[gatewayv1.GetWalletBalanceResponse](c.deps.Logger, mservice.ChainGateway, err)
+		}
+		return gsresponse.Success(&gatewayv1.GetWalletBalanceResponse{Balance: toProtoWalletBalance(stored)})
+	}
+
+	return gsresponse.Success(&gatewayv1.GetWalletBalanceResponse{Balance: onChainBalanceToProto(balance)})
+}
+
+func onChainBalanceToProto(balance *moneyv1.Money) *gatewayv1.WalletBalance {
+	if balance == nil {
+		return nil
+	}
+	zero := &moneyv1.Money{Currency: balance.Currency, Amount: "0"}
+	return &gatewayv1.WalletBalance{
+		Available:       balance,
+		PendingInbound:  zero,
+		PendingOutbound: zero,
+		CalculatedAt:    timestamppb.Now(),
+	}
 }

api/chain/gateway/internal/service/gateway/commands/wallet/onchain_balance.go

@@ -0,0 +1,124 @@
+package wallet
+
+import (
+	"context"
+	"math/big"
+	"strings"
+	"time"
+
+	"github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum/accounts/abi"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethclient"
+	"github.com/shopspring/decimal"
+	"github.com/tech/sendico/chain/gateway/storage/model"
+	"github.com/tech/sendico/pkg/merrors"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+)
+
+func onChainWalletBalance(ctx context.Context, deps Deps, wallet *model.ManagedWallet) (*moneyv1.Money, error) {
+	network := deps.Networks[strings.ToLower(strings.TrimSpace(wallet.Network))]
+	rpcURL := strings.TrimSpace(network.RPCURL)
+	if rpcURL == "" {
+		return nil, merrors.Internal("network rpc url is not configured")
+	}
+	contract := strings.TrimSpace(wallet.ContractAddress)
+	if contract == "" || !common.IsHexAddress(contract) {
+		return nil, merrors.InvalidArgument("invalid contract address")
+	}
+	if wallet.DepositAddress == "" || !common.IsHexAddress(wallet.DepositAddress) {
+		return nil, merrors.InvalidArgument("invalid wallet address")
+	}
+
+	client, err := ethclient.DialContext(ctx, rpcURL)
+	if err != nil {
+		return nil, merrors.Internal("failed to connect rpc: " + err.Error())
+	}
+	defer client.Close()
+
+	timeoutCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+
+	tokenABI, err := abi.JSON(strings.NewReader(erc20ABIJSON))
+	if err != nil {
+		return nil, merrors.Internal("failed to parse erc20 abi: " + err.Error())
+	}
+	tokenAddr := common.HexToAddress(contract)
+	walletAddr := common.HexToAddress(wallet.DepositAddress)
+
+	decimals, err := readDecimals(timeoutCtx, client, tokenABI, tokenAddr)
+	if err != nil {
+		return nil, err
+	}
+
+	bal, err := readBalanceOf(timeoutCtx, client, tokenABI, tokenAddr, walletAddr)
+	if err != nil {
+		return nil, err
+	}
+
+	dec := decimal.NewFromBigInt(bal, 0).Shift(-int32(decimals))
+	return &moneyv1.Money{Currency: wallet.TokenSymbol, Amount: dec.String()}, nil
+}
+
+func readDecimals(ctx context.Context, client *ethclient.Client, tokenABI abi.ABI, token common.Address) (uint8, error) {
+	data, err := tokenABI.Pack("decimals")
+	if err != nil {
+		return 0, merrors.Internal("failed to encode decimals call: " + err.Error())
+	}
+	msg := ethereum.CallMsg{To: &token, Data: data}
+	out, err := client.CallContract(ctx, msg, nil)
+	if err != nil {
+		return 0, merrors.Internal("decimals call failed: " + err.Error())
+	}
+	values, err := tokenABI.Unpack("decimals", out)
+	if err != nil || len(values) == 0 {
+		return 0, merrors.Internal("failed to unpack decimals")
+	}
+	if val, ok := values[0].(uint8); ok {
+		return val, nil
+	}
+	return 0, merrors.Internal("decimals returned unexpected type")
+}
+
+func readBalanceOf(ctx context.Context, client *ethclient.Client, tokenABI abi.ABI, token common.Address, wallet common.Address) (*big.Int, error) {
+	data, err := tokenABI.Pack("balanceOf", wallet)
+	if err != nil {
+		return nil, merrors.Internal("failed to encode balanceOf: " + err.Error())
+	}
+	msg := ethereum.CallMsg{To: &token, Data: data}
+	out, err := client.CallContract(ctx, msg, nil)
+	if err != nil {
+		return nil, merrors.Internal("balanceOf call failed: " + err.Error())
+	}
+	values, err := tokenABI.Unpack("balanceOf", out)
+	if err != nil || len(values) == 0 {
+		return nil, merrors.Internal("failed to unpack balanceOf")
+	}
+	raw, ok := values[0].(*big.Int)
+	if !ok {
+		return nil, merrors.Internal("balanceOf returned unexpected type")
+	}
+	return decimal.NewFromBigInt(raw, 0).BigInt(), nil
+}
+
+const erc20ABIJSON = `
+[
+	{
+		"constant": true,
+		"inputs": [],
+		"name": "decimals",
+		"outputs": [{ "name": "", "type": "uint8" }],
+		"payable": false,
+		"stateMutability": "view",
+        "type": "function"
+	},
+	{
+		"constant": true,
+		"inputs": [{ "name": "_owner", "type": "address" }],
+		"name": "balanceOf",
+		"outputs": [{ "name": "balance", "type": "uint256" }],
+		"payable": false,
+		"stateMutability": "view",
+		"type": "function"
+	}
+]`