[#365] settlement/basic: Check amount of collected assets

Some transfers from container owners into bank account may
fail due to lack of assets, so we have to deal with remaining
amount of assets in banking account.

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/innerring/processors/settlement/basic/collect.go

@@ -18,8 +18,6 @@ func (inc *IncomeSettlementContext) Collect() {
 	inc.mu.Lock()
 	defer inc.mu.Unlock()
 
-	// todo: save state of bank wallet
-
 	cachedRate, err := inc.rate.BasicRate()
 	if err != nil {
 		inc.log.Error("can't get basic income rate",

pkg/innerring/processors/settlement/basic/context.go

@@ -1,6 +1,7 @@
 package basic
 
 import (
+	"math/big"
 	"sync"
 
 	"github.com/mr-tron/base58"
@@ -21,6 +22,11 @@ type (
 		BasicRate() (uint64, error)
 	}
 
+	// BalanceFetcher uses NEP-17 compatible balance contract
+	BalanceFetcher interface {
+		Balance(id *owner.ID) (*big.Int, error)
+	}
+
 	IncomeSettlementContext struct {
 		mu sync.Mutex // lock to prevent collection and distribution in the same time
 
@@ -29,6 +35,7 @@ type (
 
 		rate        RateFetcher
 		estimations EstimationFetcher
+		balances    BalanceFetcher
 		container   common.ContainerStorage
 		placement   common.PlacementCalculator
 		exchange    common.Exchanger
@@ -42,6 +49,7 @@ type (
 		Epoch       uint64
 		Rate        RateFetcher
 		Estimations EstimationFetcher
+		Balances    BalanceFetcher
 		Container   common.ContainerStorage
 		Placement   common.PlacementCalculator
 		Exchange    common.Exchanger
@@ -59,6 +67,7 @@ func NewIncomeSettlementContext(p *IncomeSettlementContextPrms) (*IncomeSettleme
 		epoch:       p.Epoch,
 		rate:        p.Rate,
 		estimations: p.Estimations,
+		balances:    p.Balances,
 		container:   p.Container,
 		placement:   p.Placement,
 		exchange:    p.Exchange,

pkg/innerring/processors/settlement/basic/distribute.go

@@ -1,6 +1,20 @@
 package basic
 
+import (
+	"go.uber.org/zap"
+)
+
 func (inc *IncomeSettlementContext) Distribute() {
 	inc.mu.Lock()
 	defer inc.mu.Unlock()
+
+	bankBalance, err := inc.balances.Balance(inc.bankOwner)
+	if err != nil {
+		inc.log.Error("can't fetch balance of banking account",
+			zap.String("error", err.Error()))
+
+		return
+	}
+
+	_ = bankBalance
 }

pkg/innerring/settlement.go

@@ -259,6 +259,10 @@ func (b basicIncomeSettlementDeps) Estimations(epoch uint64) ([]*wrapper.Estimat
 	return result, nil
 }
 
+func (b basicIncomeSettlementDeps) Balance(id *owner.ID) (*big.Int, error) {
+	return b.balanceClient.BalanceOf(id)
+}
+
 func (s *auditSettlementCalculator) ProcessAuditSettlements(epoch uint64) {
 	(*audit.Calculator)(s).Calculate(&audit.CalculatePrm{
 		Epoch: epoch,
@@ -271,6 +275,7 @@ func (b *basicSettlementConstructor) CreateContext(epoch uint64) (*basic.IncomeS
 		Epoch:       epoch,
 		Rate:        b.dep,
 		Estimations: b.dep,
+		Balances:    b.dep,
 		Container:   b.dep,
 		Placement:   b.dep,
 		Exchange:    b.dep,