payments: unsubscribe (#7)

What
Adds a new POST /payments/unsubscribe endpoint.

Why
So that a Proprietary wallet backend can call to unregister its user accounts for payments tracking.

internal/data/payments.go

@@ -20,3 +20,13 @@ func (m *PaymentModel) SubscribeAddress(ctx context.Context, address string) err
 
 	return nil
 }
+
+func (m *PaymentModel) UnsubscribeAddress(ctx context.Context, address string) error {
+	const query = `DELETE FROM accounts WHERE stellar_address = $1`
+	_, err := m.db.ExecContext(ctx, query, address)
+	if err != nil {
+		return errors.Wrapf(err, "unsubscribing address %s to payments tracking", address)
+	}
+
+	return nil
+}

internal/serve/httphandler/payments_handler.go

@@ -33,3 +33,21 @@ func (h PaymentsHandler) SubscribeAddress(w http.ResponseWriter, r *http.Request
 		return
 	}
 }
+
+func (h PaymentsHandler) UnsubscribeAddress(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+
+	var reqBody PaymentsSubscribeRequest
+	err := httpdecode.DecodeJSON(r, &reqBody)
+	if err != nil {
+		httperror.BadRequest("Invalid request body").Render(w)
+		return
+	}
+
+	err = h.PaymentModel.UnsubscribeAddress(ctx, reqBody.Address)
+	if err != nil {
+		httperror.InternalServerError.Render(w)
+		// TODO: track in Sentry
+		return
+	}
+}

internal/serve/httphandler/payments_handler_test.go

@@ -42,9 +42,9 @@ func TestSubscribeAddress(t *testing.T) {
 		require.NoError(t, err)
 	}
 
-	t.Run("success", func(t *testing.T) {
+	t.Run("success_happy_path", func(t *testing.T) {
 		// Prepare request
-		address := "GANZZQ5WFFDAUVI4RDMRJN2QAEWO7WCLXBVIME6ZXAWO5ZEQA4ZPFWFL"
+		address := keypair.MustRandom().Address()
 		payload := fmt.Sprintf(`{ "address": "%s" }`, address)
 		req, err := http.NewRequest(http.MethodPost, "/payments/subscribe", strings.NewReader(payload))
 		require.NoError(t, err)
@@ -99,3 +99,69 @@ func TestSubscribeAddress(t *testing.T) {
 		clearAccounts(ctx)
 	})
 }
+
+func TestUnsubscribeAddress(t *testing.T) {
+	dbtest := dbtest.Open(t)
+	defer dbtest.Close()
+
+	dbConnectionPool, err := db.OpenDBConnectionPool(dbtest.DSN)
+	require.NoError(t, err)
+	defer dbConnectionPool.Close()
+
+	models, err := data.NewModels(dbConnectionPool)
+	require.NoError(t, err)
+	handler := &PaymentsHandler{
+		PaymentModel: models.Payments,
+	}
+
+	// Setup router
+	r := chi.NewRouter()
+	r.Post("/payments/unsubscribe", handler.UnsubscribeAddress)
+
+	t.Run("successHappyPath", func(t *testing.T) {
+		address := keypair.MustRandom().Address()
+		ctx := context.Background()
+
+		// Insert address in DB
+		_, err = dbConnectionPool.ExecContext(ctx, "INSERT INTO accounts (stellar_address) VALUES ($1)", address)
+		require.NoError(t, err)
+
+		// Prepare request
+		payload := fmt.Sprintf(`{ "address": "%s" }`, address)
+		req, err := http.NewRequest(http.MethodPost, "/payments/unsubscribe", strings.NewReader(payload))
+		require.NoError(t, err)
+
+		// Serve request
+		rr := httptest.NewRecorder()
+		r.ServeHTTP(rr, req)
+
+		// Assert 200 response
+		assert.Equal(t, http.StatusOK, rr.Code)
+
+		// Assert no address no longer in DB
+		var dbAddress sql.NullString
+		err = dbConnectionPool.GetContext(ctx, &dbAddress, "SELECT stellar_address FROM accounts")
+		assert.ErrorIs(t, err, sql.ErrNoRows)
+	})
+
+	t.Run("idempotency", func(t *testing.T) {
+		address := keypair.MustRandom().Address()
+		ctx := context.Background()
+
+		// Make sure DB is empty
+		_, err = dbConnectionPool.ExecContext(ctx, "DELETE FROM accounts")
+		require.NoError(t, err)
+
+		// Prepare request
+		payload := fmt.Sprintf(`{ "address": "%s" }`, address)
+		req, err := http.NewRequest(http.MethodPost, "/payments/unsubscribe", strings.NewReader(payload))
+		require.NoError(t, err)
+
+		// Serve request
+		rr := httptest.NewRecorder()
+		r.ServeHTTP(rr, req)
+
+		// Assert 200 response
+		assert.Equal(t, http.StatusOK, rr.Code)
+	})
+}

internal/serve/serve.go

@@ -81,6 +81,7 @@ func handler(deps handlerDeps) http.Handler {
 			}
 
 			r.Post("/subscribe", handler.SubscribeAddress)
+			r.Post("/unsubscribe", handler.UnsubscribeAddress)
 		})
 	})