feat: modulr connector (#25)

* add structure for wise connector

* laying out structure for modulr connector

* chore: lint

* fix: lint workflow

* chore: Rename docker images

* feat: modulr readiness

Signed-off-by: Lawrence Zawila <113581282+darkmatterpool@users.noreply.github.com>

* fix: modulr linter issue

Signed-off-by: Lawrence Zawila <113581282+darkmatterpool@users.noreply.github.com>

Signed-off-by: Lawrence Zawila <113581282+darkmatterpool@users.noreply.github.com>
Co-authored-by: Geoffrey Ragot <geoffrey.ragot@gmail.com>
Co-authored-by: Lawrence Zawila <113581282+darkmatterpool@users.noreply.github.com>

cmd/server.go

@@ -23,6 +23,7 @@ import (
 	"github.com/numary/payments/pkg/api"
 	"github.com/numary/payments/pkg/bridge/cdi"
 	"github.com/numary/payments/pkg/bridge/connectors/dummypay"
+	"github.com/numary/payments/pkg/bridge/connectors/modulr"
 	"github.com/numary/payments/pkg/bridge/connectors/stripe"
 	"github.com/numary/payments/pkg/bridge/connectors/wise"
 	bridgeHttp "github.com/numary/payments/pkg/bridge/http"
@@ -288,5 +289,9 @@ func HTTPModule() fx.Option {
 			viper.GetBool(authBearerUseScopesFlag),
 			wise.NewLoader(),
 		),
+		cdi.ConnectorModule(
+			viper.GetBool(authBearerUseScopesFlag),
+			modulr.NewLoader(),
+		),
 	)
 }

pkg/bridge/connectors/modulr/client/accounts.go

@@ -0,0 +1,43 @@
+package client
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+)
+
+type Account struct {
+	ID          string `json:"id"`
+	Name        string `json:"name"`
+	Status      string `json:"status"`
+	Balance     string `json:"balance"`
+	Currency    string `json:"currency"`
+	CustomerId  string `json:"customerId"`
+	Identifiers []struct {
+		AccountNumber string `json:"accountNumber"`
+		SortCode      string `json:"sortCode"`
+		Type          string `json:"type"`
+	} `json:"identifiers"`
+	DirectDebit bool   `json:"directDebit"`
+	CreatedDate string `json:"createdDate"`
+}
+
+func (m *Client) GetAccounts() ([]Account, error) {
+	resp, err := m.httpClient.Get(m.buildEndpoint("accounts"))
+	if err != nil {
+		return nil, err
+	}
+
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	var res responseWrapper[[]Account]
+	if err = json.NewDecoder(resp.Body).Decode(&res); err != nil {
+		return nil, err
+	}
+
+	return res.Content, nil
+}

pkg/bridge/connectors/modulr/client/client.go

@@ -0,0 +1,59 @@
+package client
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/numary/payments/pkg/bridge/connectors/modulr/hmac"
+)
+
+type apiTransport struct {
+	apiKey  string
+	headers map[string]string
+}
+
+func (t *apiTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	req.Header.Add("Authorization", t.apiKey)
+
+	return http.DefaultTransport.RoundTrip(req)
+}
+
+type responseWrapper[t any] struct {
+	Content    t   `json:"content"`
+	Size       int `json:"size"`
+	TotalSize  int `json:"totalSize"`
+	Page       int `json:"page"`
+	TotalPages int `json:"totalPages"`
+}
+
+type Client struct {
+	httpClient *http.Client
+	endpoint   string
+}
+
+func (m *Client) buildEndpoint(path string, args ...interface{}) string {
+	return fmt.Sprintf("%s/%s", m.endpoint, fmt.Sprintf(path, args...))
+}
+
+const sandboxApiEndpoint = "https://api-sandbox.modulrfinance.com/api-sandbox-token"
+
+func NewClient(apiKey, apiSecret, endpoint string) (*Client, error) {
+	if endpoint == "" {
+		endpoint = sandboxApiEndpoint
+	}
+
+	headers, err := hmac.GenerateHeaders(apiKey, apiSecret, "", false)
+	if err != nil {
+		return nil, fmt.Errorf("failed to generate headers: %w", err)
+	}
+
+	return &Client{
+		httpClient: &http.Client{
+			Transport: &apiTransport{
+				headers: headers,
+				apiKey:  apiKey,
+			},
+		},
+		endpoint: endpoint,
+	}, nil
+}

pkg/bridge/connectors/modulr/client/transactions.go

@@ -0,0 +1,41 @@
+package client
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+)
+
+type Transaction struct {
+	ID              string      `json:"id"`
+	Type            string      `json:"type"`
+	Amount          float64     `json:"amount"`
+	Credit          bool        `json:"credit"`
+	SourceID        string      `json:"sourceId"`
+	Description     string      `json:"description"`
+	PostedDate      string      `json:"postedDate"`
+	TransactionDate string      `json:"transactionDate"`
+	Account         Account     `json:"account"`
+	AdditionalInfo  interface{} `json:"additionalInfo"`
+}
+
+func (m *Client) GetTransactions(accountId string) ([]Transaction, error) {
+	resp, err := m.httpClient.Get(m.buildEndpoint("accounts/%s/transactions", accountId))
+	if err != nil {
+		return nil, err
+	}
+
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	var res responseWrapper[[]Transaction]
+	if err = json.NewDecoder(resp.Body).Decode(&res); err != nil {
+		return nil, err
+	}
+
+	return res.Content, nil
+
+}

pkg/bridge/connectors/modulr/config.go

@@ -0,0 +1,19 @@
+package modulr
+
+type Config struct {
+	APIKey    string `json:"apiKey" bson:"apiKey"`
+	APISecret string `json:"apiSecret" bson:"apiSecret"`
+	Endpoint  string `json:"endpoint" bson:"endpoint"`
+}
+
+func (c Config) Validate() error {
+	if c.APIKey == "" {
+		return ErrMissingAPIKey
+	}
+
+	if c.APISecret == "" {
+		return ErrMissingAPISecret
+	}
+
+	return nil
+}

pkg/bridge/connectors/modulr/errors.go

@@ -0,0 +1,14 @@
+package modulr
+
+import "github.com/pkg/errors"
+
+var (
+	// ErrMissingTask is returned when the task is missing.
+	ErrMissingTask = errors.New("task is not implemented")
+
+	// ErrMissingAPIKey is returned when the api key is missing from config.
+	ErrMissingAPIKey = errors.New("missing apiKey from config")
+
+	// ErrMissingAPISecret is returned when the api secret is missing from config.
+	ErrMissingAPISecret = errors.New("missing apiSecret from config")
+)

pkg/bridge/connectors/modulr/hmac/hmac.go

@@ -0,0 +1,58 @@
+package hmac
+
+import (
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/pkg/errors"
+)
+
+const (
+	authorizationHeader = "Authorization"
+	dateHeader          = "Date"
+	emptyString         = ""
+	nonceHeader         = "x-mod-nonce"
+	retry               = "x-mod-retry"
+	retryTrue           = "true"
+	retryFalse          = "false"
+)
+
+var ErrInvalidCredentials = errors.New("invalid api credentials")
+
+func GenerateHeaders(apiKey string, apiSecret string, nonce string, hasRetry bool) (map[string]string, error) {
+	if apiKey == "" || apiSecret == "" {
+		return nil, ErrInvalidCredentials
+	}
+
+	return constructHeadersMap(apiKey, apiSecret, nonce, hasRetry, time.Now()), nil
+}
+
+func constructHeadersMap(apiKey string, apiSecret string, nonce string, hasRetry bool,
+	timestamp time.Time) map[string]string {
+	headers := make(map[string]string)
+	date := timestamp.Format(time.RFC1123)
+	nonce = generateNonceIfEmpty(nonce)
+
+	headers[dateHeader] = date
+	headers[authorizationHeader] = buildSignature(apiKey, apiSecret, nonce, date)
+	headers[nonceHeader] = nonce
+	headers[retry] = parseRetryBool(hasRetry)
+
+	return headers
+}
+
+func generateNonceIfEmpty(nonce string) string {
+	if nonce == emptyString {
+		nonce = uuid.New().String()
+	}
+
+	return nonce
+}
+
+func parseRetryBool(hasRetry bool) string {
+	if hasRetry {
+		return retryTrue
+	}
+
+	return retryFalse
+}

pkg/bridge/connectors/modulr/hmac/hmac_test.go

@@ -0,0 +1,55 @@
+package hmac
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGenerateReturnsAnHMACString(t *testing.T) {
+	headers, _ := GenerateHeaders("api_key", "api_secret", "", false)
+	expectedSignature := "Signature keyId=\"api_key\",algorithm=\"hmac-sha1\",headers=\"date x-mod-nonce\",signature=\""
+	assert.Equal(t, expectedSignature, headers["Authorization"][0:86], "generate should return the hmac headers")
+}
+
+func TestGenerateReturnsADateHeader(t *testing.T) {
+	timestamp := time.Date(2020, 1, 2, 15, 4, 5, 0, time.UTC)
+
+	headers := constructHeadersMap("api_key", "api_secret", "", false, timestamp)
+
+	expectedDate := "Thu, 02 Jan 2020 15:04:05 UTC"
+
+	assert.Equal(t, expectedDate, headers["Date"])
+}
+
+func TestGenerateReturnsANonceHeaderWithExpectedValue(t *testing.T) {
+	nonce := "thisIsTheNonce"
+	headers, _ := GenerateHeaders("api_key", "api_secret", nonce, false)
+	assert.Equal(t, nonce, headers["x-mod-nonce"])
+}
+
+func TestGenerateReturnsARetryHeaderWithTrueIfRetryIsExpected(t *testing.T) {
+	headers, _ := GenerateHeaders("api_key", "api_secret", "", true)
+	assert.Equal(t, "true", headers["x-mod-retry"])
+}
+
+func TestGenerateReturnsARetryHeaderWithFalseIfRetryIsNotExpected(t *testing.T) {
+	headers, _ := GenerateHeaders("api_key", "api_secret", "", false)
+	assert.Equal(t, "false", headers["x-mod-retry"])
+}
+
+func TestGenerateReturnsAGeneratedNonceHeaderIfNonceIsEmpty(t *testing.T) {
+	headers, _ := GenerateHeaders("api_key", "api_secret", "", false)
+	assert.True(t, headers["x-mod-nonce"] != "", "x-mod-nonce header should have been populated")
+}
+
+func TestGenerateThrowsErrorIfApiKeyIsNull(t *testing.T) {
+	_, err := GenerateHeaders("", "api_secret", "", false)
+	assert.ErrorIs(t, err, ErrInvalidCredentials)
+}
+
+func TestGenerateThrowsErrorIfApiSecretIsNull(t *testing.T) {
+	_, err := GenerateHeaders("api_key", "", "", false)
+	assert.ErrorIs(t, err, ErrInvalidCredentials)
+}

pkg/bridge/connectors/modulr/hmac/signature_generator.go

@@ -0,0 +1,32 @@
+package hmac
+
+import (
+	"crypto/hmac"
+	"crypto/sha1"
+	"encoding/base64"
+	"net/url"
+)
+
+const (
+	algorithm   = "algorithm=\"hmac-sha1\","
+	datePrefix  = "date: "
+	headers     = "headers=\"date x-mod-nonce\","
+	prefix      = "signature=\""
+	suffix      = "\""
+	newline     = "\n"
+	nonceKey    = "x-mod-nonce: "
+	keyIdPrefix = "Signature keyId=\""
+)
+
+func buildSignature(apiKey string, apiSecret string, nonce string, date string) string {
+	keyID := keyIdPrefix + apiKey + "\","
+
+	mac := hmac.New(sha1.New, []byte(apiSecret))
+	mac.Write([]byte(datePrefix + date + newline + nonceKey + nonce))
+
+	encodedMac := mac.Sum(nil)
+	base64Encoded := base64.StdEncoding.EncodeToString(encodedMac)
+	encodedSignature := prefix + url.QueryEscape(base64Encoded) + suffix
+
+	return keyID + algorithm + headers + encodedSignature
+}