move model validation into pattern classes and link from recurring_todo model

app/models/recurring_todos/abstract_repeat_pattern.rb

@@ -8,6 +8,30 @@ module RecurringTodos
       @user = user
     end
 
+    def start_from
+      get :start_from
+    end
+
+    def end_date
+      get :end_date
+    end
+
+    def ends_on
+      get :ends_on
+    end
+
+    def target
+      get :target
+    end
+
+    def show_always
+      get :show_always
+    end
+
+    def show_from_delta
+      get :show_from_delta
+    end
+
     def build_recurring_todo(attributes)
       @recurring_todo = @user.recurring_todos.build(attributes)
     end
@@ -16,7 +40,53 @@ module RecurringTodos
       recurring_todo.assign_attributes(attributes)
       recurring_todo
     end
-    
+
+    def build_from_recurring_todo(recurring_todo)
+      @recurring_todo = recurring_todo
+      @attributes = recurring_todo.attributes
+    end
+
+    def validate
+      starts_and_ends_on_validations
+      set_recurrence_on_validations
+    end
+
+    def starts_and_ends_on_validations
+      errors[:base] << "The start date needs to be filled in" if start_from.blank?
+      case ends_on
+      when 'ends_on_number_of_times'
+        errors[:base] << "The number of recurrences needs to be filled in for 'Ends on'" if number_of_occurences.blank?
+      when "ends_on_end_date"
+        errors[:base] << "The end date needs to be filled in for 'Ends on'" if end_date.blank?
+      else
+        errors[:base] << "The end of the recurrence is not selected" unless ends_on == "no_end_date"
+      end
+    end
+
+    def set_recurrence_on_validations
+      # show always or x days before due date. x not null
+      case target
+      when 'show_from_date'
+        # no validations
+      when 'due_date'
+        errors[:base] << "Please select when to show the action" if show_always.nil?
+        unless show_always
+          errors[:base] << "Please fill in the number of days to show the todo before the due date" if show_from_delta.blank?
+        end
+      else
+        raise Exception.new, "unexpected value of recurrence target selector '#{target}'"
+      end
+    end
+
+    def errors
+      @recurring_todo.errors
+    end
+
+    def get attribute
+      # handle attribute as symbol and as string
+      @attributes[attribute] || @attributes[attribute.to_s]
+    end
+
   end
   
 end