accounts: add functionality to update balance by given amount

.github/workflows/main.yml

@@ -253,6 +253,8 @@ jobs:
         unit_type:
           - unit-race
           - unit
+          - unit dbbackend=postgres
+          - unit dbbackend=sqlite
     steps:
       - name: git checkout
         uses: actions/checkout@v4

accounts/interface.go

@@ -1,7 +1,9 @@
 package accounts
 
 import (
+	"bytes"
 	"context"
+	"encoding/binary"
 	"encoding/hex"
 	"errors"
 	"fmt"
@@ -55,6 +57,31 @@ func ParseAccountID(idStr string) (*AccountID, error) {
 	return &id, nil
 }
 
+// ToInt64 converts an AccountID to its int64 representation.
+func (a AccountID) ToInt64() (int64, error) {
+	var value int64
+	buf := bytes.NewReader(a[:])
+	if err := binary.Read(buf, byteOrder, &value); err != nil {
+		return 0, err
+	}
+
+	return value, nil
+}
+
+// AccountIDFromInt64 converts an int64 to an AccountID.
+func AccountIDFromInt64(value int64) (AccountID, error) {
+	var (
+		a   = AccountID{}
+		buf = new(bytes.Buffer)
+	)
+	if err := binary.Write(buf, binary.BigEndian, value); err != nil {
+		return a, err
+	}
+	copy(a[:], buf.Bytes())
+
+	return a, nil
+}
+
 // String returns the string representation of the AccountID.
 func (a AccountID) String() string {
 	return hex.EncodeToString(a[:])
@@ -241,6 +268,12 @@ type Store interface {
 		status lnrpc.Payment_PaymentStatus,
 		options ...UpsertPaymentOption) (bool, error)
 
+	// AdjustAccountBalance modifies the given account balance by adding or
+	// deducting the specified amount, depending on whether isAddition is
+	// true or false.
+	AdjustAccountBalance(ctx context.Context, alias AccountID,
+		amount lnwire.MilliSatoshi, isAddition bool) error
+
 	// DeleteAccountPayment removes a payment entry from the account with
 	// the given ID. It will return the ErrPaymentNotAssociated error if the
 	// payment is not associated with the account.

accounts/rpcserver.go

@@ -132,6 +132,53 @@ func (s *RPCServer) UpdateAccount(ctx context.Context,
 	return marshalAccount(account), nil
 }
 
+// UpdateBalance adds or deducts an amount from an existing account in the
+// account database.
+func (s *RPCServer) UpdateBalance(ctx context.Context,
+	req *litrpc.UpdateAccountBalanceRequest) (*litrpc.Account, error) {
+
+	var (
+		isAddition bool
+		amount     lnwire.MilliSatoshi
+	)
+
+	switch reqType := req.GetUpdate().(type) {
+	case *litrpc.UpdateAccountBalanceRequest_Add:
+		log.Infof("[addbalance] id=%s, label=%v, amount=%d",
+			req.Id, req.Label, reqType.Add)
+
+		isAddition = true
+		amount = lnwire.MilliSatoshi(reqType.Add * 1000)
+
+	case *litrpc.UpdateAccountBalanceRequest_Deduct:
+		log.Infof("[deductbalance] id=%s, label=%v, amount=%d",
+			req.Id, req.Label, reqType.Deduct)
+
+		isAddition = false
+		amount = lnwire.MilliSatoshi(reqType.Deduct * 1000)
+	}
+
+	if amount <= 0 {
+		return nil, fmt.Errorf("amount %v must be greater than 0",
+			int64(amount/1000))
+	}
+
+	accountID, err := s.findAccount(ctx, req.Id, req.Label)
+	if err != nil {
+		return nil, err
+	}
+
+	// Ask the service to update the account.
+	account, err := s.service.UpdateBalance(
+		ctx, accountID, amount, isAddition,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	return marshalAccount(account), nil
+}
+
 // ListAccounts returns all accounts that are currently stored in the account
 // database.
 func (s *RPCServer) ListAccounts(ctx context.Context,

accounts/service.go

@@ -345,6 +345,32 @@ func (s *InterceptorService) UpdateAccount(ctx context.Context,
 	return s.store.Account(ctx, accountID)
 }
 
+// UpdateBalance adds or deducts an amount from an existing account in the
+// account database.
+func (s *InterceptorService) UpdateBalance(ctx context.Context,
+	accountID AccountID, amount lnwire.MilliSatoshi,
+	isAddition bool) (*OffChainBalanceAccount, error) {
+
+	s.Lock()
+	defer s.Unlock()
+
+	// As this function updates account balances, we require that the
+	// service is running before we execute it.
+	if !s.isRunningUnsafe() {
+		// This case can only happen if the service is disabled while
+		// we're processing a request.
+		return nil, ErrAccountServiceDisabled
+	}
+
+	// Adjust the balance of the account in the db.
+	err := s.store.AdjustAccountBalance(ctx, accountID, amount, isAddition)
+	if err != nil {
+		return nil, fmt.Errorf("unable to update account: %w", err)
+	}
+
+	return s.store.Account(ctx, accountID)
+}
+
 // Account retrieves an account from the bolt DB and un-marshals it. If the
 // account cannot be found, then ErrAccNotFound is returned.
 func (s *InterceptorService) Account(ctx context.Context,

accounts/store_kvdb.go

@@ -307,6 +307,45 @@ func (s *BoltStore) UpsertAccountPayment(_ context.Context, id AccountID,
 	return known, s.updateAccount(id, update)
 }
 
+// AdjustAccountBalance modifies the given account balance by adding or
+// deducting the specified amount, depending on whether isAddition is true or
+// false.
+//
+// NOTE: This is part of the Store interface.
+func (s *BoltStore) AdjustAccountBalance(_ context.Context,
+	id AccountID, amount lnwire.MilliSatoshi, isAddition bool) error {
+
+	update := func(account *OffChainBalanceAccount) error {
+		if amount > math.MaxInt64 {
+			return fmt.Errorf("amount %v exceeds the maximum of %v",
+				int64(amount/1000), int64(math.MaxInt64)/1000)
+		}
+
+		if amount <= 0 {
+			return fmt.Errorf("amount %v must be greater that 0",
+				amount)
+		}
+
+		if isAddition {
+			account.CurrentBalance += int64(amount)
+		} else {
+			if account.CurrentBalance-int64(amount) < 0 {
+				return fmt.Errorf("cannot deduct %v from the "+
+					"current balance %v, as the resulting "+
+					"balance would be below 0",
+					int64(amount/1000),
+					account.CurrentBalance/1000)
+			}
+
+			account.CurrentBalance -= int64(amount)
+		}
+
+		return nil
+	}
+
+	return s.updateAccount(id, update)
+}
+
 // DeleteAccountPayment removes a payment entry from the account with the given
 // ID. It will return the ErrPaymentNotAssociated error if the payment is not
 // associated with the account.