Move letter too long banner message over from utils, also refactor

app/utils.py

@@ -43,6 +43,8 @@ FAILURE_STATUSES = ['failed', 'temporary-failure', 'permanent-failure',
                     'technical-failure', 'virus-scan-failed', 'validation-failed']
 REQUESTED_STATUSES = SENDING_STATUSES + DELIVERED_STATUSES + FAILURE_STATUSES
 
+LETTER_MAX_PAGES = 10
+
 with open('{}/email_domains.txt'.format(
     os.path.dirname(os.path.realpath(__file__))
 )) as email_domains:
@@ -543,6 +545,12 @@ def get_letter_printing_statement(status, created_at):
         return 'Printed on {} at 5:30pm'.format(printed_date)
 
 
+def is_letter_too_long(page_count):
+    if not page_count:
+        return False
+    return page_count > LETTER_MAX_PAGES
+
+
 class PermanentRedirect(RequestRedirect):
     """
     In Werkzeug 0.15.0 the status code for RequestRedirect changed from 301 to 308.