First pass at GetBalance

indexer/indexer.go

@@ -87,6 +87,7 @@ type Indexer struct {
 	asserter       *asserter.Asserter
 	database       storage.Database
 	blockStorage   *storage.BlockStorage
+	balanceStorage *storage.BalanceStorage
 	coinStorage    *storage.CoinStorage
 	workers        []storage.BlockWorker
 
@@ -208,6 +209,7 @@ func Initialize(
 		&BalanceStorageHelper{asserter},
 		&BalanceStorageHandler{},
 	)
+	i.balanceStorage = balanceStorage
 
 	i.workers = []storage.BlockWorker{coinStorage, balanceStorage}
 
@@ -758,7 +760,11 @@ func (i *Indexer) GetBlockTransaction(
 	blockIdentifier *types.BlockIdentifier,
 	transactionIdentifier *types.TransactionIdentifier,
 ) (*types.Transaction, error) {
-	return i.blockStorage.GetBlockTransaction(ctx, blockIdentifier, transactionIdentifier)
+	return i.blockStorage.GetBlockTransaction(
+		ctx,
+		blockIdentifier,
+		transactionIdentifier,
+	)
 }
 
 // GetCoins returns all unspent coins for a particular *types.AccountIdentifier.
@@ -768,3 +774,27 @@ func (i *Indexer) GetCoins(
 ) ([]*types.Coin, *types.BlockIdentifier, error) {
 	return i.coinStorage.GetCoins(ctx, accountIdentifier)
 }
+
+func (i *Indexer) GetBalance(
+	ctx context.Context,
+	accountIdentifier *types.AccountIdentifier,
+	currency *types.Currency,
+	blockIdentifier *types.PartialBlockIdentifier,
+) (*types.Amount, *types.BlockIdentifier, error) {
+	blockResponse, err := i.GetBlockLazy(ctx, blockIdentifier)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	amount, err := i.balanceStorage.GetBalance(
+		ctx,
+		accountIdentifier,
+		currency,
+		blockResponse.Block.BlockIdentifier,
+	)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return amount, blockResponse.Block.BlockIdentifier, nil
+}

main.go

@@ -154,7 +154,7 @@ func main() {
 	// requests.
 	asserter, err := asserter.NewServer(
 		bitcoin.OperationTypes,
-		false,
+		true,
 		[]*types.NetworkIdentifier{cfg.Network},
 		nil,
 	)

services/account_service.go

@@ -49,6 +49,10 @@ func (s *AccountAPIService) AccountBalance(
 		return nil, wrapErr(ErrUnavailableOffline, nil)
 	}
 
+	// If we are fetching the current balance,
+	// return all coins for an address and calculate
+	// the balance from those coins.
+	if request.BlockIdentifier == nil {
 		coins, block, err := s.i.GetCoins(ctx, request.AccountIdentifier)
 		if err != nil {
 			return nil, wrapErr(ErrUnableToGetCoins, err)
@@ -72,4 +76,24 @@ func (s *AccountAPIService) AccountBalance(
 				},
 			},
 		}, nil
+	}
+
+	// If we are fetching a historical balance,
+	// use balance storage and don't return coins.
+	amount, block, err := s.i.GetBalance(
+		ctx,
+		request.AccountIdentifier,
+		s.config.Currency,
+		request.BlockIdentifier,
+	)
+	if err != nil {
+		return nil, wrapErr(ErrUnableToGetBalance, err)
+	}
+
+	return &types.AccountBalanceResponse{
+		BlockIdentifier: block,
+		Balances: []*types.Amount{
+			amount,
+		},
+	}, nil
 }

services/errors.go

@@ -40,6 +40,7 @@ var (
 		ErrUnableToGetCoins,
 		ErrTransactionNotFound,
 		ErrCouldNotGetFeeRate,
+		ErrUnableToGetBalance,
 	}
 
 	// ErrUnimplemented is returned when an endpoint
@@ -61,6 +62,7 @@ var (
 	ErrNotReady = &types.Error{
 		Code:      2, //nolint
 		Message:   "Bitcoind is not ready",
+		Retriable: true,
 	}
 
 	// ErrBitcoind is returned when bitcoind
@@ -173,6 +175,14 @@ var (
 		Code:    17, // nolint
 		Message: "Could not get suggested fee rate",
 	}
+
+	// ErrUnableToGetBalance is returned by the indexer
+	// when it is not possible to get the balance
+	// of a *types.AccountIdentifier.
+	ErrUnableToGetBalance = &types.Error{
+		Code:    18, //nolint
+		Message: "Unable to get balance",
+	}
 )
 
 // wrapErr adds details to the types.Error provided. We use a function

services/types.go

@@ -48,7 +48,10 @@ type Client interface {
 
 // Indexer is used by the servicers to get block and account data.
 type Indexer interface {
-	GetBlockLazy(context.Context, *types.PartialBlockIdentifier) (*types.BlockResponse, error)
+	GetBlockLazy(
+		context.Context,
+		*types.PartialBlockIdentifier,
+	) (*types.BlockResponse, error)
 	GetBlockTransaction(
 		context.Context,
 		*types.BlockIdentifier,
@@ -62,6 +65,12 @@ type Indexer interface {
 		context.Context,
 		[]*types.Coin,
 	) ([]*bitcoin.ScriptPubKey, error)
+	GetBalance(
+		context.Context,
+		*types.AccountIdentifier,
+		*types.Currency,
+		*types.PartialBlockIdentifier,
+	) (*types.Amount, *types.BlockIdentifier, error)
 }
 
 type unsignedTransaction struct {