text: from io import BytesIO
  
  from flask import current_app, jsonify, request, send_file, url_for
  
  from app import api_user, authenticated_service
  from app.dao import notifications_dao
  from app.letters.utils import get_letter_pdf_and_metadata
  from app.models import (
      LETTER_TYPE,
      NOTIFICATION_PENDING_VIRUS_CHECK,
      NOTIFICATION_TECHNICAL_FAILURE,
      NOTIFICATION_VIRUS_SCAN_FAILED,
  )
  from app.schema_validation import validate
  from app.v2.errors import BadRequestError, PDFNotReadyError
  from app.v2.notifications import v2_notification_blueprint
  from app.v2.notifications.notification_schemas import (
      get_notifications_request,
      notification_by_id,
  )
  
  
  @v2_notification_blueprint.route("/<notification_id>", methods=['GET'])
  def get_notification_by_id(notification_id):
      _data = {"notification_id": notification_id}
      validate(_data, notification_by_id)
      notification = notifications_dao.get_notification_with_personalisation(
          authenticated_service.id, notification_id, key_type=None
      )
      return jsonify(notification.serialize()), 200
  
  
  @v2_notification_blueprint.route('/<notification_id>/pdf', methods=['GET'])
  def get_pdf_for_notification(notification_id):
      _data = {"notification_id": notification_id}
      validate(_data, notification_by_id)
      notification = notifications_dao.get_notification_by_id(
          notification_id, authenticated_service.id, _raise=True
      )
  
      if notification.notification_type != LETTER_TYPE:
          raise BadRequestError(message="Notification is not a letter")
  
      if notification.status == NOTIFICATION_VIRUS_SCAN_FAILED:
          raise BadRequestError(message='File did not pass the virus scan')
  
      if notification.status == NOTIFICATION_TECHNICAL_FAILURE:
          raise BadRequestError(message='PDF not available for letters in status {}'.format(notification.status))
  
      if notification.status == NOTIFICATION_PENDING_VIRUS_CHECK:
          raise PDFNotReadyError()
  
      try:
          pdf_data, metadata = get_letter_pdf_and_metadata(notification)
      except Exception:
          raise PDFNotReadyError()
  
      return send_file(path_or_file=BytesIO(pdf_data), mimetype='application/pdf')
  
  
  @v2_notification_blueprint.route("", methods=['GET'])
  def get_notifications():
      _data = request.args.to_dict(flat=False)
  
      # flat=False makes everything a list, but we only ever allow one value for "older_than"
      if 'older_than' in _data:
          _data['older_than'] = _data['older_than'][0]
  
      # and client reference
      if 'reference' in _data:
          _data['reference'] = _data['reference'][0]
  
      if 'include_jobs' in _data:
          _data['include_jobs'] = _data['include_jobs'][0]
  
      data = validate(_data, get_notifications_request)
  
      paginated_notifications = notifications_dao.get_notifications_for_service(
          str(authenticated_service.id),
          filter_dict=data,
          key_type=api_user.key_type,
          personalisation=True,
          older_than=data.get('older_than'),
          client_reference=data.get('reference'),
          page_size=current_app.config.get('API_PAGE_SIZE'),
          include_jobs=data.get('include_jobs'),
          count_pages=False
      )
  
      def _build_links(notifications):
          _links = {
              'current': url_for(".get_notifications", _external=True, **data),
          }
  
          if len(notifications):
              next_query_params = dict(data, older_than=notifications[-1].id)
              _links['next'] = url_for(".get_notifications", _external=True, **next_query_params)
  
          return _links
  
      return jsonify(
          notifications=[notification.serialize() for notification in paginated_notifications.items],
          links=_build_links(paginated_notifications.items)
      ), 200
  