Refactor and harmonise metadata for invalid letters with those sent from admin app

app/letters/utils.py

@@ -1,9 +1,13 @@
+import boto3
 import io
+import json
 import math
+
+from app.models import KEY_TYPE_TEST, SECOND_CLASS, RESOLVE_POSTAGE_FOR_FILE_NAME, NOTIFICATION_VALIDATION_FAILED
+
 from datetime import datetime, timedelta
 from enum import Enum
 
-import boto3
 from flask import current_app
 
 from notifications_utils.letter_timings import LETTER_PROCESSING_DEADLINE
@@ -11,8 +15,6 @@ from notifications_utils.pdf import pdf_page_count
 from notifications_utils.s3 import s3upload
 from notifications_utils.timezones import convert_utc_to_bst
 
-from app.models import KEY_TYPE_TEST, SECOND_CLASS, RESOLVE_POSTAGE_FOR_FILE_NAME, NOTIFICATION_VALIDATION_FAILED
-
 
 class ScanErrorType(Enum):
     ERROR = 1
@@ -130,9 +132,9 @@ def move_error_pdf_to_scan_bucket(source_filename):
 def move_scan_to_invalid_pdf_bucket(source_filename, message=None, invalid_pages=None, page_count=None):
     metadata = {}
     if message:
-        metadata["validation_failed_message"] = message
+        metadata["message"] = message
     if invalid_pages:
-        metadata["invalid_pages"] = "-".join(map(str, invalid_pages))
+        metadata["invalid_pages"] = json.dumps(invalid_pages)
     if page_count:
         metadata["page_count"] = str(page_count)
 
@@ -228,7 +230,12 @@ def letter_print_day(created_at):
 
 
 def get_page_count(pdf):
-    pages = pdf_page_count(io.BytesIO(pdf))
+    return pdf_page_count(io.BytesIO(pdf))
+
+
+def get_billable_units_for_letter_page_count(page_count):
+    if not page_count:
+        return 0
     pages_per_sheet = 2
-    billable_units = math.ceil(pages / pages_per_sheet)
+    billable_units = math.ceil(page_count / pages_per_sheet)
     return billable_units