Resolve "follow up visits should be based on visit one date"

Closes #169 (closed)

smash/web/models/visit.py

@@ -52,11 +52,14 @@ class Visit(models.Model):
         self.save()
 
         if (not self.subject.dead) and (not self.subject.resigned):
-            visit_started = self.datetime_begin
+            visit_started = Visit.objects.filter(subject=self.subject).filter(visit_number=1)[0].datetime_begin
+            follow_up_number = Visit.objects.filter(subject=self.subject).count() + 1
 
-            time_to_next_visit = datetime.timedelta(days=365)
+            delta_days = 365
             if self.subject.type == SUBJECT_TYPE_CHOICES_CONTROL:
-                time_to_next_visit = datetime.timedelta(days=365 * 3 + 366)
+                delta_days = 365 * 3 + 366
+
+            time_to_next_visit = datetime.timedelta(days=delta_days * (follow_up_number - 1))
 
             Visit.objects.create(
                 subject=self.subject,