cmd/server: whitelist only certain CustomerStatus transistions

Not every CustomerStatus can be converted into another, so we need to block bad transistions.

Issue: #5

cmd/server/customers.go

@@ -250,6 +250,39 @@ type updateCustomerStatusRequest struct {
 	Status  CustomerStatus `json:"status"`
 }
 
+// validCustomerStatusTransition determines if a future CustomerStatus is valid for a given
+// Customer. There are several rules which apply to a CustomerStatus, such as:
+//  - Deceased, Rejected statuses can never be changed
+//  - KYC is only valid if the Customer has first, last, address, and date of birth
+//  - OFAC can only be after an OFAC search has been performed (and search info recorded)
+//  - CIP can only be if the SSN has been set
+func validCustomerStatusTransition(existing *client.Customer, futureStatus CustomerStatus) error {
+	eql := func(s string, status CustomerStatus) bool {
+		return strings.EqualFold(s, string(status))
+	}
+	// Check Deceased and Rejected
+	if eql(existing.Status, CustomerStatusDeceased) || eql(existing.Status, CustomerStatusRejected) {
+		return fmt.Errorf("customer status '%s' cannot be changed", existing.Status)
+	}
+	switch futureStatus {
+	case CustomerStatusKYC:
+		if existing.FirstName == "" || existing.LastName == "" {
+			return fmt.Errorf("customer=%s is missing fist/last name", existing.Id)
+		}
+		if existing.BirthDate.IsZero() {
+			return fmt.Errorf("customer=%s is missing date of birth", existing.Id)
+		}
+		if len(existing.Addresses) == 0 { // TODO(adam): we should probably check existing.Addresses.exists(_.Validated)
+			return fmt.Errorf("customer=%s is missing an Address", existing.Id)
+		}
+	case CustomerStatusOFAC: // TODO(adam): need to impl lookup
+		return fmt.Errorf("customers=%s %s to OFAC transition needs to lookup OFAC search results", existing.Id, existing.Status)
+	case CustomerStatusCIP: // TODO(adam): need to impl lookup
+		return fmt.Errorf("customers=%s %s to CIP transition needs to lookup encrypted SSN", existing.Id, existing.Status)
+	}
+	return nil
+}
+
 func updateCustomerStatus(logger log.Logger, repo customerRepository) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		w = wrapResponseWriter(logger, w, r)
@@ -265,6 +298,16 @@ func updateCustomerStatus(logger log.Logger, repo customerRepository) http.Handl
 			return
 		}
 
+		cust, err := repo.getCustomer(customerId)
+		if err != nil {
+			moovhttp.Problem(w, err)
+			return
+		}
+		if err := validCustomerStatusTransition(cust, req.Status); err != nil {
+			moovhttp.Problem(w, err)
+			return
+		}
+
 		// Update Customer's status in the database
 		if err := repo.updateCustomerStatus(customerId, req.Status, req.Comment); err != nil {
 			moovhttp.Problem(w, err)

cmd/server/customers_test.go

@@ -13,6 +13,7 @@ import (
 	"net/http/httptest"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/moov-io/base"
 	client "github.com/moov-io/customers/client"
@@ -540,3 +541,49 @@ func TestCustomers__validateMetadata(t *testing.T) {
 		t.Error("expected error")
 	}
 }
+
+func TestCustomers__validCustomerStatusTransition(t *testing.T) {
+	cust := &client.Customer{
+		Id:     base.ID(),
+		Status: CustomerStatusNone,
+	}
+
+	if err := validCustomerStatusTransition(cust, CustomerStatusDeceased); err != nil {
+		t.Errorf("expected no error: %v", err)
+	}
+
+	// block Deceased and Rejected customers
+	cust.Status = CustomerStatusDeceased
+	if err := validCustomerStatusTransition(cust, CustomerStatusKYC); err == nil {
+		t.Error("expected error")
+	}
+	cust.Status = CustomerStatusRejected
+	if err := validCustomerStatusTransition(cust, CustomerStatusKYC); err == nil {
+		t.Error("expected error")
+	}
+
+	// normal KYC approval (rejected due to missing info)
+	cust.FirstName, cust.LastName = "Jane", "Doe"
+	cust.Status = CustomerStatusReviewRequired
+	if err := validCustomerStatusTransition(cust, CustomerStatusKYC); err == nil {
+		t.Error("expected error")
+	}
+	cust.BirthDate = time.Now()
+	if err := validCustomerStatusTransition(cust, CustomerStatusKYC); err == nil {
+		t.Error("expected error")
+	}
+	cust.Addresses = append(cust.Addresses, client.Address{
+		Type:     "primary",
+		Address1: "123 1st st",
+	})
+
+	// OFAC and CIP transistions are WIP // TODO(adam): impl both transistions
+	cust.Status = CustomerStatusReviewRequired
+	if err := validCustomerStatusTransition(cust, CustomerStatusOFAC); err == nil {
+		t.Error("OFAC transistion is WIP")
+	}
+	cust.Status = CustomerStatusReviewRequired
+	if err := validCustomerStatusTransition(cust, CustomerStatusCIP); err == nil {
+		t.Error("CIP transistion is WIP")
+	}
+}