Refactor construction API

server/services/common.go

@@ -1,3 +1,54 @@
 package services
 
+import (
+	"encoding/json"
+	"math/big"
+	"strings"
+)
+
 type objectsMap map[string]interface{}
+
+func toObjectsMap(value any) (objectsMap, error) {
+	data, err := json.Marshal(value)
+	if err != nil {
+		return nil, err
+	}
+
+	var result objectsMap
+	err = json.Unmarshal(data, &result)
+	if err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}
+
+func fromObjectsMap(obj objectsMap, value any) error {
+	data, err := json.Marshal(obj)
+	if err != nil {
+		return err
+	}
+
+	err = json.Unmarshal(data, value)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func isZeroAmount(amount string) bool {
+	return amount == "" || amount == "0" || amount == "-0"
+}
+
+func getMagnitudeOfAmount(amount string) string {
+	return strings.Trim(amount, "-")
+}
+
+func multiplyUint64(a uint64, b uint64) *big.Int {
+	return big.NewInt(0).Mul(big.NewInt(0).SetUint64(a), big.NewInt(0).SetUint64(b))
+}
+
+func addBigInt(a *big.Int, b *big.Int) *big.Int {
+	return big.NewInt(0).Add(a, b)
+}

server/services/common_test.go

@@ -0,0 +1,56 @@
+package services
+
+import (
+	"math"
+	"math/big"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+type dummy struct {
+	A string `json:"a"`
+	B string `json:"b"`
+	C uint64 `json:"c"`
+}
+
+func Test_ToObjectsMapAndFromObjectsMap(t *testing.T) {
+	t.Parallel()
+
+	dummyOriginal := &dummy{
+		A: "a",
+		B: "b",
+		C: 42,
+	}
+
+	dummyMap, err := toObjectsMap(dummyOriginal)
+	require.Nil(t, err)
+
+	dummyConverted := &dummy{}
+	err = fromObjectsMap(dummyMap, dummyConverted)
+	require.Nil(t, err)
+
+	require.Equal(t, dummyOriginal, dummyConverted)
+}
+
+func Test_IsZeroAmount(t *testing.T) {
+	require.True(t, isZeroAmount(""))
+	require.True(t, isZeroAmount("0"))
+	require.True(t, isZeroAmount("-0"))
+	require.False(t, isZeroAmount("1"))
+	require.False(t, isZeroAmount("-1"))
+}
+
+func Test_GetMagnitudeOfAmount(t *testing.T) {
+	require.Equal(t, "100", getMagnitudeOfAmount("100"))
+	require.Equal(t, "100", getMagnitudeOfAmount("-100"))
+}
+
+func Test_MultiplyUint64(t *testing.T) {
+	require.Equal(t, "340282366920938463426481119284349108225", multiplyUint64(math.MaxUint64, math.MaxUint64).String())
+	require.Equal(t, "1", multiplyUint64(1, 1).String())
+}
+
+func Test_AddBigInt(t *testing.T) {
+	require.Equal(t, "12", addBigInt(big.NewInt(7), big.NewInt(5)).String())
+}

server/services/constructionMetadata.go

@@ -0,0 +1,88 @@
+package services
+
+import (
+	"encoding/json"
+	"errors"
+
+	"github.com/ElrondNetwork/elrond-proxy-go/data"
+)
+
+type constructionMetadata struct {
+	Sender         string `json:"sender"`
+	Receiver       string `json:"receiver"`
+	Nonce          uint64 `json:"nonce"`
+	Amount         string `json:"amount"`
+	CurrencySymbol string `json:"currencySymbol"`
+	GasLimit       uint64 `json:"gasLimit"`
+	GasPrice       uint64 `json:"gasPrice"`
+	Data           []byte `json:"data"`
+	ChainID        string `json:"chainID"`
+	Version        int    `json:"version"`
+}
+
+func newConstructionMetadata(obj objectsMap) (*constructionMetadata, error) {
+	result := &constructionMetadata{}
+	err := fromObjectsMap(obj, result)
+	if err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}
+
+func (metadata *constructionMetadata) toTransactionJson() ([]byte, error) {
+	tx, err := metadata.toTransaction()
+	if err != nil {
+		return nil, err
+	}
+
+	txJson, err := json.Marshal(tx)
+	if err != nil {
+		return nil, err
+	}
+
+	return txJson, nil
+}
+
+func (metadata *constructionMetadata) toTransaction() (*data.Transaction, error) {
+	err := metadata.validate()
+	if err != nil {
+		return nil, err
+	}
+
+	tx := &data.Transaction{}
+	tx.Sender = metadata.Sender
+	tx.Receiver = metadata.Receiver
+	tx.Nonce = metadata.Nonce
+	tx.Value = metadata.Amount
+	tx.GasLimit = metadata.GasLimit
+	tx.GasPrice = metadata.GasPrice
+	tx.Data = metadata.Data
+	tx.ChainID = metadata.ChainID
+	tx.Version = uint32(metadata.Version)
+
+	return tx, nil
+}
+
+func (metadata *constructionMetadata) validate() error {
+	if len(metadata.Sender) == 0 {
+		return errors.New("missing metadata: 'sender'")
+	}
+	if len(metadata.Receiver) == 0 {
+		return errors.New("missing metadata: 'receiver'")
+	}
+	if metadata.GasLimit == 0 {
+		return errors.New("missing metadata: 'gasLimit'")
+	}
+	if metadata.GasPrice == 0 {
+		return errors.New("missing metadata: 'gasPrice'")
+	}
+	if metadata.Version != 1 {
+		return errors.New("bad metadata: unexpected 'version'")
+	}
+	if len(metadata.ChainID) == 0 {
+		return errors.New("missing metadata: 'chainID'")
+	}
+
+	return nil
+}

server/services/constructionMetadata_test.go

@@ -0,0 +1,82 @@
+package services
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestConstructionMetadata_ToTransactionJson(t *testing.T) {
+	t.Parallel()
+
+	options := &constructionMetadata{
+		Sender:         "alice",
+		Receiver:       "bob",
+		Nonce:          42,
+		Amount:         "1234",
+		CurrencySymbol: "XeGLD",
+		GasLimit:       80000,
+		GasPrice:       1000000000,
+		Data:           []byte("hello"),
+		ChainID:        "T",
+		Version:        1,
+	}
+
+	expectedJson := `{"nonce":42,"value":"1234","receiver":"bob","sender":"alice","gasPrice":1000000000,"gasLimit":80000,"data":"aGVsbG8=","chainID":"T","version":1}`
+	actualJson, err := options.toTransactionJson()
+	require.Nil(t, err)
+	require.Equal(t, expectedJson, string(actualJson))
+}
+
+func TestConstructionMetadata_Validate(t *testing.T) {
+	t.Parallel()
+
+	require.ErrorContains(t, (&constructionMetadata{}).validate(), "missing metadata: 'sender'")
+
+	require.ErrorContains(t, (&constructionMetadata{
+		Sender: "alice",
+	}).validate(), "missing metadata: 'receiver'")
+
+	require.ErrorContains(t, (&constructionMetadata{
+		Sender:   "alice",
+		Receiver: "bob",
+	}).validate(), "missing metadata: 'gasLimit'")
+
+	require.ErrorContains(t, (&constructionMetadata{
+		Sender:   "alice",
+		Receiver: "bob",
+		GasLimit: 50000,
+	}).validate(), "missing metadata: 'gasPrice'")
+
+	require.ErrorContains(t, (&constructionMetadata{
+		Sender:   "alice",
+		Receiver: "bob",
+		GasLimit: 50000,
+		GasPrice: 1000000000,
+	}).validate(), "bad metadata: unexpected 'version'")
+
+	require.ErrorContains(t, (&constructionMetadata{
+		Sender:   "alice",
+		Receiver: "bob",
+		GasLimit: 50000,
+		GasPrice: 1000000000,
+		Version:  42,
+	}).validate(), "bad metadata: unexpected 'version'")
+
+	require.ErrorContains(t, (&constructionMetadata{
+		Sender:   "alice",
+		Receiver: "bob",
+		GasLimit: 50000,
+		GasPrice: 1000000000,
+		Version:  1,
+	}).validate(), "missing metadata: 'chainID'")
+
+	require.Nil(t, (&constructionMetadata{
+		Sender:   "alice",
+		Receiver: "bob",
+		GasLimit: 50000,
+		GasPrice: 1000000000,
+		Version:  1,
+		ChainID:  "T",
+	}).validate())
+}

server/services/constructionOptions.go

@@ -0,0 +1,61 @@
+package services
+
+import (
+	"errors"
+)
+
+type constructionOptions struct {
+	Sender         string `json:"sender"`
+	Receiver       string `json:"receiver"`
+	Amount         string `json:"amount"`
+	CurrencySymbol string `json:"currencySymbol"`
+	GasLimit       uint64 `json:"gasLimit"`
+	GasPrice       uint64 `json:"gasPrice"`
+	Data           []byte `json:"data"`
+}
+
+func newConstructionOptions(obj objectsMap) (*constructionOptions, error) {
+	result := &constructionOptions{}
+	err := fromObjectsMap(obj, result)
+	if err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}
+
+func (options *constructionOptions) coalesceGasLimit(estimatedGasLimit uint64) uint64 {
+	if options.GasLimit == 0 {
+		return estimatedGasLimit
+	}
+
+	return options.GasLimit
+}
+
+func (options *constructionOptions) coalesceGasPrice(minGasPrice uint64) uint64 {
+	if options.GasPrice == 0 {
+		return minGasPrice
+	}
+
+	return options.GasPrice
+}
+
+func (options *constructionOptions) validate(nativeCurrencySymbol string) error {
+	if len(options.Sender) == 0 {
+		return errors.New("missing option: 'sender'")
+	}
+	if len(options.Receiver) == 0 {
+		return errors.New("missing option: 'receiver'")
+	}
+	if isZeroAmount(options.Amount) {
+		return errors.New("missing option: 'amount'")
+	}
+	if len(options.CurrencySymbol) == 0 {
+		return errors.New("missing option: 'currencySymbol'")
+	}
+	if len(options.Data) > 0 && options.CurrencySymbol != nativeCurrencySymbol {
+		return errors.New("for custom currencies, option 'data' must be empty")
+	}
+
+	return nil
+}