Updated API to handle pre-compiled pdfs

* added a method to letter/utils.py to get the PDF document from the S3
bucket
* added the logic to return the pdf or to produce a png of the pdf

app/letters/utils.py

@@ -1,5 +1,6 @@
 from datetime import datetime, timedelta
 
+import boto3
 from flask import current_app
 
 from notifications_utils.s3 import s3upload
@@ -10,6 +11,8 @@ from app.variables import Retention
 LETTERS_PDF_FILE_LOCATION_STRUCTURE = \
     '{folder}/NOTIFY.{reference}.{duplex}.{letter_class}.{colour}.{crown}.{date}.pdf'
 
+PRECOMPILED_BUCKET_PREFIX = '{folder}/NOTIFY.{reference}'
+
 
 def get_letter_pdf_filename(reference, crown):
     now = datetime.utcnow()
@@ -31,6 +34,15 @@ def get_letter_pdf_filename(reference, crown):
     return upload_file_name
 
 
+def get_bucket_prefix_for_notification(notification):
+    upload_file_name = PRECOMPILED_BUCKET_PREFIX.format(
+        folder=notification.created_at.date(),
+        reference=notification.reference
+    ).upper()
+
+    return upload_file_name
+
+
 def upload_letter_pdf(notification, pdf_data):
     current_app.logger.info("PDF Letter {} reference {} created at {}, {} bytes".format(
         notification.id, notification.reference, notification.created_at, len(pdf_data)))
@@ -48,3 +60,19 @@ def upload_letter_pdf(notification, pdf_data):
 
     current_app.logger.info("Uploaded letters PDF {} to {} for notification id {}".format(
         upload_file_name, current_app.config['LETTERS_PDF_BUCKET_NAME'], notification.id))
+
+
+def get_letter_pdf(notification):
+    bucket_name = current_app.config['LETTERS_PDF_BUCKET_NAME']
+
+    s3 = boto3.resource('s3')
+    bucket = s3.Bucket(bucket_name)
+
+    for item in bucket.objects.filter(Prefix=get_bucket_prefix_for_notification(notification)):
+        obj = s3.Object(
+            bucket_name=bucket_name,
+            key=item.key
+        )
+        file_content = obj.get()["Body"].read()
+
+    return file_content

app/template/rest.py

@@ -18,6 +18,7 @@ from app.dao.templates_dao import (
     dao_get_template_by_id)
 from notifications_utils.template import SMSMessageTemplate
 from app.dao.services_dao import dao_fetch_service_by_id
+from app.letters.utils import get_letter_pdf
 from app.models import SMS_TYPE
 from app.notifications.validators import service_has_permission, check_reply_to
 from app.schemas import (template_schema, template_history_schema)
@@ -185,6 +186,7 @@ def redact_template(template, data):
 
 @template_blueprint.route('/preview/<uuid:notification_id>/<file_type>', methods=['GET'])
 def preview_letter_template_by_notification_id(service_id, notification_id, file_type):
+
     if file_type not in ('pdf', 'png'):
         raise InvalidRequest({'content': ["file_type must be pdf or png"]}, status_code=400)
 
@@ -194,36 +196,65 @@ def preview_letter_template_by_notification_id(service_id, notification_id, file
 
     template = dao_get_template_by_id(notification.template_id)
 
-    template_for_letter_print = {
+    if template.hidden and template.name == 'Pre-compiled PDF':
-        "id": str(notification.template_id),
-        "subject": template.subject,
-        "content": template.content,
-        "version": str(template.version)
-    }
 
-    service = dao_fetch_service_by_id(service_id)
+        pdf_file = get_letter_pdf(notification)
 
-    data = {
+        content = base64.b64encode(pdf_file).decode('utf-8')
-        'letter_contact_block': notification.reply_to_text,
-        'template': template_for_letter_print,
-        'values': notification.personalisation,
-        'dvla_org_id': service.dvla_organisation_id,
-    }
 
-    resp = requests_post(
+        if file_type == 'png':
-        '{}/preview.{}{}'.format(
-            current_app.config['TEMPLATE_PREVIEW_API_HOST'],
-            file_type,
-            '?page={}'.format(page) if page else ''
-        ),
-        json=data,
-        headers={'Authorization': 'Token {}'.format(current_app.config['TEMPLATE_PREVIEW_API_KEY'])}
-    )
 
-    if resp.status_code != 200:
+            url = '{}//precompiled-preview.png{}'.format(
-        raise InvalidRequest(
+                    current_app.config['TEMPLATE_PREVIEW_API_HOST'],
-            'Error generating preview for {}'.format(notification_id), status_code=500
+                    '?page={}'.format(page) if page else ''
+                )
+
+            resp = requests_post(
+                url,
+                data=content,
+                headers={'Authorization': 'Token {}'.format(current_app.config['TEMPLATE_PREVIEW_API_KEY'])}
+            )
+
+            if resp.status_code != 200:
+                raise InvalidRequest(
+                    'Error generating preview for {}'.format(notification_id), status_code=500
+                )
+
+            content = base64.b64encode(resp.content).decode('utf-8')
+
+    else:
+
+        template_for_letter_print = {
+            "id": str(notification.template_id),
+            "subject": template.subject,
+            "content": template.content,
+            "version": str(template.version)
+        }
+
+        service = dao_fetch_service_by_id(service_id)
+
+        data = {
+            'letter_contact_block': notification.reply_to_text,
+            'template': template_for_letter_print,
+            'values': notification.personalisation,
+            'dvla_org_id': service.dvla_organisation_id,
+        }
+
+        resp = requests_post(
+            '{}/preview.{}{}'.format(
+                current_app.config['TEMPLATE_PREVIEW_API_HOST'],
+                file_type,
+                '?page={}'.format(page) if page else ''
+            ),
+            json=data,
+            headers={'Authorization': 'Token {}'.format(current_app.config['TEMPLATE_PREVIEW_API_KEY'])}
         )
 
-    content = base64.b64encode(resp.content).decode('utf-8')
+        if resp.status_code != 200:
+            raise InvalidRequest(
+                'Error generating preview for {}'.format(notification_id), status_code=500
+            )
+
+        content = base64.b64encode(resp.content).decode('utf-8')
+
     return jsonify({"content": content})