feat: add suggested fees api (#2604)

services/wallet/api.go

@@ -266,3 +266,8 @@ func (api *API) FetchPrices(ctx context.Context, symbols []string, currency stri
 	log.Debug("call to FetchPrices")
 	return fetchCryptoComparePrices(symbols, currency)
 }
+
+func (api *API) GetSuggestedFees(ctx context.Context, chainID uint64) (*SuggestedFees, error) {
+	log.Debug("call to GetSuggestedFees")
+	return api.s.feesManager.suggestedFees(ctx, chainID)
+}

services/wallet/fees.go

@@ -0,0 +1,107 @@
+package wallet
+
+import (
+	"context"
+	"math/big"
+	"sort"
+	"strings"
+
+	"github.com/ethereum/go-ethereum/consensus/misc"
+	"github.com/ethereum/go-ethereum/params"
+	"github.com/status-im/status-go/rpc"
+)
+
+type SuggestedFees struct {
+	GasPrice             *big.Float `json:"gasPrice"`
+	BaseFee              *big.Float `json:"baseFee"`
+	MaxPriorityFeePerGas *big.Float `json:"maxPriorityFeePerGas"`
+	MaxFeePerGasLow      *big.Float `json:"maxFeePerGasLow"`
+	MaxFeePerGasMedium   *big.Float `json:"maxFeePerGasMedium"`
+	MaxFeePerGasHigh     *big.Float `json:"maxFeePerGasHigh"`
+}
+
+type FeeHistory struct {
+	BaseFeePerGas []string `json:"baseFeePerGas"`
+}
+
+type FeeManager struct {
+	RPCClient *rpc.Client
+}
+
+func weiToGwei(val *big.Int) *big.Float {
+	result := new(big.Float)
+	result.SetInt(val)
+
+	unit := new(big.Int)
+	unit.SetInt64(params.GWei)
+
+	return result.Quo(result, new(big.Float).SetInt(unit))
+}
+
+func (f *FeeManager) suggestedFees(ctx context.Context, chainID uint64) (*SuggestedFees, error) {
+	backend, err := f.RPCClient.EthClient(chainID)
+	if err != nil {
+		return nil, err
+	}
+
+	gasPrice, err := backend.SuggestGasPrice(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	maxPriorityFeePerGas, err := backend.SuggestGasTipCap(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	block, err := backend.BlockByNumber(ctx, nil)
+	if err != nil {
+		return nil, err
+	}
+	config := params.MainnetChainConfig
+	baseFee := misc.CalcBaseFee(config, block.Header())
+
+	var feeHistory FeeHistory
+
+	err = f.RPCClient.Call(&feeHistory, chainID, "eth_feeHistory", 101, "latest", nil)
+	if err != nil {
+		return nil, err
+	}
+
+	fees := []*big.Int{}
+	for _, fee := range feeHistory.BaseFeePerGas {
+		i := new(big.Int)
+		i.SetString(strings.Replace(fee, "0x", "", 1), 16)
+		fees = append(fees, i)
+	}
+	sort.Slice(fees, func(i, j int) bool { return fees[i].Cmp(fees[j]) < 0 })
+
+	perc10 := fees[int64(0.1*float64(len(fees)))-1]
+	perc20 := fees[int64(0.2*float64(len(fees)))-1]
+
+	var maxFeePerGasMedium *big.Int
+	if baseFee.Cmp(perc20) >= 0 {
+		maxFeePerGasMedium = baseFee
+	} else {
+		maxFeePerGasMedium = perc20
+	}
+
+	if maxPriorityFeePerGas.Cmp(maxFeePerGasMedium) > 0 {
+		maxFeePerGasMedium = maxPriorityFeePerGas
+	}
+
+	maxFeePerGasHigh := new(big.Int).Mul(maxPriorityFeePerGas, big.NewInt(2))
+	twoTimesBaseFee := new(big.Int).Mul(baseFee, big.NewInt(2))
+	if twoTimesBaseFee.Cmp(maxFeePerGasHigh) > 0 {
+		maxFeePerGasHigh = twoTimesBaseFee
+	}
+
+	return &SuggestedFees{
+		GasPrice:             weiToGwei(gasPrice),
+		BaseFee:              weiToGwei(baseFee),
+		MaxPriorityFeePerGas: weiToGwei(maxPriorityFeePerGas),
+		MaxFeePerGasLow:      weiToGwei(perc10),
+		MaxFeePerGasMedium:   weiToGwei(maxFeePerGasMedium),
+		MaxFeePerGasHigh:     weiToGwei(maxFeePerGasHigh),
+	}, nil
+}

services/wallet/service.go

@@ -32,6 +32,7 @@ func NewService(db *sql.DB, rpcClient *rpc.Client, accountFeed *event.Feed, open
 		transferController:    transferController,
 		cryptoOnRampManager:   cryptoOnRampManager,
 		openseaAPIKey:         openseaAPIKey,
+		feesManager:           &FeeManager{rpcClient},
 	}
 }
 
@@ -44,6 +45,7 @@ type Service struct {
 	favouriteManager      *FavouriteManager
 	cryptoOnRampManager   *CryptoOnRampManager
 	transferController    *transfer.Controller
+	feesManager           *FeeManager
 	started               bool
 	openseaAPIKey         string
 }