import logging
from requests_aws4auth import AWS4Auth
from elasticsearch import RequestsHttpConnection
from elasticsearch_dsl import Index, Document, Integer, Date, Text, Ip
from elasticsearch_dsl.connections import connections

logger = logging.getLogger(__name__)

ELASTICSEARCH_CONNECTION_ALIAS = 'LogEntry'
INDEX_NAME_PREFIX = 'logentry_'


class LogEntry(Document):
  random_id = Integer()  # random id is the tie-breaker for sorting in pagination.
  # https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-search-after.html
  kind_id = Integer()
  account_id = Integer()
  performer_id = Integer()
  repository_id = Integer()
  ip = Ip()
  metadata_json = Text()
  datetime = Date()

  @classmethod
  def init_with_template(cls, index_prefix=INDEX_NAME_PREFIX, index_settings=None):
    """
    Create the index template, and populate LogEntry's mapping and index settings.
    """
    wildcard_index = Index(name=index_prefix + '*', using=ELASTICSEARCH_CONNECTION_ALIAS)
    wildcard_index.settings(**(index_settings or {}))
    wildcard_index.document(cls)

    cls._index = wildcard_index
    cls._index_prefix = index_prefix
    index_template = wildcard_index.as_template(index_prefix)
    index_template.save(using=ELASTICSEARCH_CONNECTION_ALIAS)

  def save(self, **kwargs):
    # We group the logs based on year and month as different indexes, so that
    # dropping those indexes based on retention range ~1 month is easy.
    kwargs['index'] = self.datetime.strftime(self._index_prefix + '%Y-%m')
    return super(LogEntry, self).save(**kwargs)


class AWSElasticsearchLogs(object):
  """
  Model for logs operations stored in an AWS Elasticsearch cluster.
  """

  def __init__(self, host, port, aws_access_key, aws_secret_key, aws_region,
               index_prefix=INDEX_NAME_PREFIX, index_settings=None):
    # for options in index_settings, please refer to:
    # https://www.elastic.co/guide/en/elasticsearch/guide/master/_index_settings.html
    # some index settings are set at index creation time, and therefore, you should NOT
    # change those settings once the index is set.
    assert len(index_prefix) >= 1
    http_auth = None
    if aws_access_key and aws_secret_key:
      http_auth = AWS4Auth(aws_access_key, aws_secret_key, aws_region, 'es')
    else:
      logger.warn("Connecting to AWS Elasticsearch without HTTP AUTH")

    connections.create_connection(
      alias=ELASTICSEARCH_CONNECTION_ALIAS,
      hosts=[{
        'host': host,
        'port': port
      }],
      http_auth=http_auth,
      use_ssl=True,
      verify_certs=True,
      connection_class=RequestsHttpConnection,
    )

    LogEntry.init_with_template(index_prefix, index_settings)