fix: readd priceoracle

pkg/settlement/swap/priceoracle/mock/priceoracle.go

@@ -0,0 +1,48 @@
+// Copyright 2021 The Swarm Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package mock
+
+import (
+	"context"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+type Service struct {
+	rate   *big.Int
+	deduct *big.Int
+}
+
+func New(rate *big.Int, deduct *big.Int) Service {
+	return Service{
+		rate:   rate,
+		deduct: deduct,
+	}
+}
+
+func (s Service) Start() {
+}
+
+func (s Service) GetPrice(ctx context.Context) (*big.Int, *big.Int, error) {
+	return s.rate, s.deduct, nil
+}
+
+func (s Service) CurrentRates() (exchangeRate *big.Int, deduction *big.Int, err error) {
+	return s.rate, s.deduct, nil
+}
+
+func (s Service) Close() error {
+	return nil
+}
+
+func DiscoverPriceOracleAddress(chainID int64) (priceOracleAddress common.Address, found bool) {
+	return common.Address{}, false
+}
+
+func (s Service) SetValues(rate *big.Int, deduct *big.Int) {
+	s.rate = rate
+	s.deduct = deduct
+}

pkg/settlement/swap/priceoracle/priceoracle.go

@@ -0,0 +1,154 @@
+// Copyright 2021 The Swarm Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package priceoracle
+
+import (
+	"context"
+	"errors"
+	"io"
+	"math/big"
+	"time"
+
+	"github.com/ethereum/go-ethereum/accounts/abi"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethersphere/bee/pkg/logging"
+	"github.com/ethersphere/bee/pkg/transaction"
+	"github.com/ethersphere/go-price-oracle-abi/priceoracleabi"
+)
+
+var (
+	errDecodeABI          = errors.New("could not decode abi data")
+	goerliContractAddress = common.HexToAddress("0x0c9de531dcb38b758fe8a2c163444a5e54ee0db2")
+)
+
+type service struct {
+	logger             logging.Logger
+	priceOracleAddress common.Address
+	transactionService transaction.Service
+	exchangeRate       *big.Int
+	deduction          *big.Int
+	timeDivisor        int64
+	quitC              chan struct{}
+}
+
+type Service interface {
+	io.Closer
+	// Deposit starts depositing erc20 token into the chequebook. This returns once the transactions has been broadcast.
+	CurrentRates() (exchangeRate *big.Int, deduction *big.Int, err error)
+	GetPrice(ctx context.Context) (*big.Int, *big.Int, error)
+	Start()
+}
+
+var (
+	priceOracleABI = transaction.ParseABIUnchecked(priceoracleabi.PriceOracleABIv0_1_0)
+)
+
+func New(logger logging.Logger, priceOracleAddress common.Address, transactionService transaction.Service, timeDivisor int64) Service {
+	return &service{
+		logger:             logger,
+		priceOracleAddress: priceOracleAddress,
+		transactionService: transactionService,
+		exchangeRate:       big.NewInt(0),
+		deduction:          nil,
+		quitC:              make(chan struct{}),
+		timeDivisor:        timeDivisor,
+	}
+}
+
+func (s *service) Start() {
+	ctx, cancel := context.WithCancel(context.Background())
+	go func() {
+		defer cancel()
+		<-s.quitC
+	}()
+
+	go func() {
+		defer cancel()
+		for {
+			exchangeRate, deduction, err := s.getPrice(ctx)
+			if err != nil {
+				s.logger.Errorf("could not get price: %v", err)
+			}
+
+			s.exchangeRate = exchangeRate
+			s.deduction = deduction
+
+			ts := time.Now().Unix()
+
+			timeUntilNextPoll := time.Duration(s.timeDivisor-ts%s.timeDivisor) * time.Second
+
+			s.logger.Tracef("updated exchange rate to %d and deduction to %d", exchangeRate, deduction)
+
+			select {
+			case <-s.quitC:
+				return
+			case <-time.After(timeUntilNextPoll):
+			}
+		}
+	}()
+}
+
+func (s *service) GetPrice(ctx context.Context) (*big.Int, *big.Int, error) {
+	return s.getPrice(ctx)
+}
+
+func (s *service) getPrice(ctx context.Context) (*big.Int, *big.Int, error) {
+	callData, err := priceOracleABI.Pack("getPrice")
+	if err != nil {
+		return nil, nil, err
+	}
+	result, err := s.transactionService.Call(ctx, &transaction.TxRequest{
+		To:   &s.priceOracleAddress,
+		Data: callData,
+	})
+	if err != nil {
+		return nil, nil, err
+	}
+
+	results, err := priceOracleABI.Unpack("getPrice", result)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	if len(results) != 2 {
+		return nil, nil, errDecodeABI
+	}
+
+	exchangeRate, ok := abi.ConvertType(results[0], new(big.Int)).(*big.Int)
+	if !ok || exchangeRate == nil {
+		return nil, nil, errDecodeABI
+	}
+
+	deduction, ok := abi.ConvertType(results[1], new(big.Int)).(*big.Int)
+	if !ok || deduction == nil {
+		return nil, nil, errDecodeABI
+	}
+
+	return exchangeRate, deduction, nil
+}
+
+func (s *service) CurrentRates() (exchangeRate *big.Int, deduction *big.Int, err error) {
+	if s.exchangeRate.Cmp(big.NewInt(0)) == 0 {
+		return nil, nil, errors.New("exchange rate not yet available")
+	}
+	if s.deduction == nil {
+		return nil, nil, errors.New("deduction amount not yet available")
+	}
+	return s.exchangeRate, s.deduction, nil
+}
+
+func (s *service) Close() error {
+	close(s.quitC)
+	return nil
+}
+
+// DiscoverPriceOracleAddress returns the canonical price oracle for this chainID
+func DiscoverPriceOracleAddress(chainID int64) (priceOracleAddress common.Address, found bool) {
+	if chainID == 5 {
+		// goerli
+		return goerliContractAddress, true
+	}
+	return common.Address{}, false
+}

pkg/settlement/swap/priceoracle/priceoracle_test.go

@@ -0,0 +1,61 @@
+// Copyright 2021 The Swarm Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package priceoracle_test
+
+import (
+	"context"
+	"io/ioutil"
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethersphere/bee/pkg/logging"
+	"github.com/ethersphere/bee/pkg/settlement/swap/priceoracle"
+	"github.com/ethersphere/bee/pkg/transaction"
+	transactionmock "github.com/ethersphere/bee/pkg/transaction/mock"
+	"github.com/ethersphere/go-price-oracle-abi/priceoracleabi"
+)
+
+var (
+	priceOracleABI = transaction.ParseABIUnchecked(priceoracleabi.PriceOracleABIv0_1_0)
+)
+
+func TestExchangeGetPrice(t *testing.T) {
+	priceOracleAddress := common.HexToAddress("0xabcd")
+
+	expectedPrice := big.NewInt(100)
+	expectedDeduce := big.NewInt(200)
+
+	result := make([]byte, 64)
+	expectedPrice.FillBytes(result[0:32])
+	expectedDeduce.FillBytes(result[32:64])
+
+	ex := priceoracle.New(
+		logging.New(ioutil.Discard, 0),
+		priceOracleAddress,
+		transactionmock.New(
+			transactionmock.WithABICall(
+				&priceOracleABI,
+				priceOracleAddress,
+				result,
+				"getPrice",
+			),
+		),
+		1,
+	)
+
+	price, deduce, err := ex.GetPrice(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if expectedPrice.Cmp(price) != 0 {
+		t.Fatalf("got wrong price. wanted %d, got %d", expectedPrice, price)
+	}
+
+	if expectedDeduce.Cmp(deduce) != 0 {
+		t.Fatalf("got wrong deduce. wanted %d, got %d", expectedDeduce, deduce)
+	}
+}