Grab metadata when getting pdf letter preview from S3

Also use this metadata to decide whether preview pages need
overlay or not. So far we have always added overlay when validation
has failed. Now we will only show it when validation failed due to
content being outside of printable area.

app/letters/utils.py

@@ -164,7 +164,7 @@ def get_file_names_from_error_bucket():
     return bucket.objects.filter(Prefix="ERROR")
 
 
-def get_letter_pdf(notification):
+def get_letter_pdf_and_metadata(notification):
     bucket_name, prefix = get_bucket_name_and_prefix_for_notification(notification)
 
     s3 = boto3.resource('s3')
@@ -174,8 +174,8 @@ def get_letter_pdf(notification):
     obj = s3.Object(
         bucket_name=bucket_name,
         key=item.key
-    )
-    return obj.get()["Body"].read()
+    ).get()
+    return obj["Body"].read(), obj["Metadata"]
 
 
 def _move_s3_object(source_bucket, source_filename, target_bucket, target_filename, metadata=None):

app/template/rest.py

@@ -32,7 +32,7 @@ from app.errors import (
     register_errors,
     InvalidRequest
 )
-from app.letters.utils import get_letter_pdf
+from app.letters.utils import get_letter_pdf_and_metadata
 from app.models import SMS_TYPE, Template, SECOND_CLASS, LETTER_TYPE
 from app.notifications.validators import service_has_permission, check_reply_to
 from app.schema_validation import validate
@@ -231,11 +231,12 @@ def preview_letter_template_by_notification_id(service_id, notification_id, file
     notification = get_notification_by_id(notification_id)
 
     template = dao_get_template_by_id(notification.template_id)
+    metadata = {}
 
     if template.is_precompiled_letter:
         try:
 
-            pdf_file = get_letter_pdf(notification)
+            pdf_file, metadata = get_letter_pdf_and_metadata(notification)
 
         except botocore.exceptions.ClientError as e:
             raise InvalidRequest(
@@ -245,7 +246,7 @@ def preview_letter_template_by_notification_id(service_id, notification_id, file
             )
 
         content = base64.b64encode(pdf_file).decode('utf-8')
-        overlay = request.args.get('overlay')
+        overlay = metadata.get("message") == "content-outside-printable-area"
         page_number = page if page else "1"
 
         if overlay:
@@ -300,7 +301,7 @@ def preview_letter_template_by_notification_id(service_id, notification_id, file
         )
         response_content = _get_png_preview_or_overlaid_pdf(url, data, notification.id, json=True)
 
-    return jsonify({"content": response_content})
+    return jsonify({"content": response_content, "metadata": metadata})
 
 
 def _get_png_preview_or_overlaid_pdf(url, data, notification_id, json=True):

app/v2/notifications/get_notifications.py

@@ -4,7 +4,7 @@ from flask import jsonify, request, url_for, current_app, send_file
 
 from app import api_user, authenticated_service
 from app.dao import notifications_dao
-from app.letters.utils import get_letter_pdf
+from app.letters.utils import get_letter_pdf_and_metadata
 from app.schema_validation import validate
 from app.v2.errors import BadRequestError, PDFNotReadyError
 from app.v2.notifications import v2_notification_blueprint
@@ -48,7 +48,7 @@ def get_pdf_for_notification(notification_id):
         raise PDFNotReadyError()
 
     try:
-        pdf_data = get_letter_pdf(notification)
+        pdf_data, metadata = get_letter_pdf_and_metadata(notification)
     except Exception:
         raise PDFNotReadyError()