More advance signup flow

app/services/new_supplier.rb

@@ -1,19 +1,20 @@
 class NewSupplier
   include ActiveAttr::Model
   attr_accessor :current_employee
+  attr_reader :employee, :supplier
 
   attribute :supplier_name
   attribute :email
   attribute :password
   attribute :password_confirmation
 
-  without_current_supplier = { unless: 'current_employee.present?' }
+  without_current_employee = { unless: 'current_employee.present?' }
   validates :supplier_name, presence: true
-  validates :email, email: without_current_supplier
-  validates :password, presence: without_current_supplier, confirmation: without_current_supplier
+  validates :email, email: without_current_employee
+  validates :password, presence: without_current_employee, confirmation: without_current_employee
 
   validate :supplier_name_uniqueness
-  validate :employee_uniqueness
+  validate :employee_uniqueness_or_existence
 
   def save
     if valid?
@@ -27,15 +28,22 @@ class NewSupplier
   private
 
   def persist!
-    employee = Employee.new unconfirmed_email: email, password: password, password_confirmation: password_confirmation
+    @employee ||= Employee.new email: email, password: password, password_confirmation: password_confirmation
     raise "Cannot create employee with #{attributes.inspect}" unless employee.save
-    supplier = Supplier.create name: supplier_name
+    @supplier = Supplier.create name: supplier_name
     supplier.add_manager employee
   end
 
-  def employee_uniqueness
+  def employee_uniqueness_or_existence
     return if current_employee.present?
-    errors.add :email, :taken if Employee.count_by_email(email) > 0
+    if Employee.count_by_email(email) > 0
+      employee = Employee.find_by_email(email)
+      if employee.valid_password? password
+        @employee = employee
+      else
+        errors.add :email, :taken
+      end
+    end
   end
 
   def supplier_name_uniqueness