from math import log10

from app import app
from data.model.image import (get_images_eligible_for_scan, get_image_pk_field,
                              get_max_id_for_sec_scan, get_min_id_for_sec_scan)
from util.migrate.allocator import yield_random_entries

from workers.securityworker.models_interface import (
  ScanToken,
  SecurityWorkerDataInterface
)

class PreOCIModel(SecurityWorkerDataInterface):
  def candidates_to_scan(self, target_version, start_token=None):
    def batch_query():
      return get_images_eligible_for_scan(target_version)

    # Find the minimum ID.
    min_id = None
    if start_token is not None:
      min_id = start_token.min_id
    else:
      min_id = app.config.get('SECURITY_SCANNER_INDEXING_MIN_ID')
      if min_id is None:
        min_id = get_min_id_for_sec_scan(target_version)

    # Get the ID of the last image we can analyze. Will be None if there are no images in the
    # database.
    max_id = get_max_id_for_sec_scan()
    if max_id is None:
      return (None, None)

    if min_id is None or min_id > max_id:
      return (None, None)

    # 4^log10(total) gives us a scalable batch size into the billions.
    batch_size = int(4 ** log10(max(10, max_id - min_id)))

    # TODO: Once we have a clean shared NamedTuple for Images, send that to the secscan analyzer
    # rather than the database Image itself.
    iterator = yield_random_entries(
      batch_query,
      get_image_pk_field(),
      batch_size,
      max_id,
      min_id,
    )

    return (iterator, ScanToken(max_id + 1))


pre_oci_model = PreOCIModel()