import json
import logging

from calendar import timegm
from peewee import JOIN, fn, PeeweeException
from datetime import datetime, timedelta
from cachetools import lru_cache

import data
from data.database import LogEntry, LogEntryKind, User, RepositoryActionCount, db
from data.model import config, user, DataModelException

logger = logging.getLogger(__name__)

ACTIONS_ALLOWED_WITHOUT_AUDIT_LOGGING = ['pull_repo']


def _logs_query(selections, start_time, end_time, performer=None, repository=None, namespace=None,
                ignore=None, model=LogEntry):
  """ Returns a query for selecting logs from the table, with various options and filters. """
  # TODO(LogMigrate): Remove the branch once we're back on LogEntry only.
  joined = (model.select(*selections).switch(model)
            .where(model.datetime >= start_time, model.datetime < end_time))

  if repository:
    joined = joined.where(model.repository == repository)

  if performer:
    joined = joined.where(model.performer == performer)

  if namespace and not repository:
    namespace_user = user.get_user_or_org(namespace)
    if namespace_user is None:
      raise DataModelException('Invalid namespace requested')

    joined = joined.where(model.account == namespace_user.id)

  if ignore:
    kind_map = get_log_entry_kinds()
    ignore_ids = [kind_map[kind_name] for kind_name in ignore]
    joined = joined.where(~(model.kind << ignore_ids))

  return joined


@lru_cache(maxsize=1)
def get_log_entry_kinds():
  kind_map = {}
  for kind in LogEntryKind.select():
    kind_map[kind.id] = kind.name
    kind_map[kind.name] = kind.id

  return kind_map


def _get_log_entry_kind(name):
  kinds = get_log_entry_kinds()
  return kinds[name]


def get_aggregated_logs(start_time, end_time, performer=None, repository=None, namespace=None,
                        ignore=None, model=LogEntry):
  """ Returns the count of logs, by kind and day, for the logs matching the given filters. """
  # TODO(LogMigrate): Remove the branch once we're back on LogEntry only.
  date = db.extract_date('day', model.datetime)
  selections = [model.kind, date.alias('day'), fn.Count(model.id).alias('count')]
  query = _logs_query(selections, start_time, end_time, performer, repository, namespace, ignore,
                      model=model)
  return query.group_by(date, model.kind)


def get_logs_query(start_time, end_time, performer=None, repository=None, namespace=None,
                   ignore=None, model=LogEntry):
  """ Returns the logs matching the given filters. """
  # TODO(LogMigrate): Remove the branch once we're back on LogEntry only.
  Performer = User.alias()
  Account = User.alias()
  selections = [model, Performer]

  if namespace is None and repository is None:
    selections.append(Account)

  query = _logs_query(selections, start_time, end_time, performer, repository, namespace, ignore,
                      model=model)
  query = (query.switch(model).join(Performer, JOIN.LEFT_OUTER,
                                       on=(model.performer == Performer.id).alias('performer')))

  if namespace is None and repository is None:
    query = (query.switch(model).join(Account, JOIN.LEFT_OUTER,
                                         on=(model.account == Account.id).alias('account')))

  return query


def _json_serialize(obj):
  if isinstance(obj, datetime):
    return timegm(obj.utctimetuple())

  return obj


def log_action(kind_name, user_or_organization_name, performer=None, repository=None, ip=None,
               metadata={}, timestamp=None):
  """ Logs an entry in the LogEntry table. """
  if not timestamp:
    timestamp = datetime.today()

  account = None
  if user_or_organization_name is not None:
    account = User.get(User.username == user_or_organization_name).id
  else:
    account = config.app_config.get('SERVICE_LOG_ACCOUNT_ID')
    if account is None:
      account = User.select(fn.Min(User.id)).tuples().get()[0]

  if performer is not None:
    performer = performer.id

  if repository is not None:
    repository = repository.id

  kind = _get_log_entry_kind(kind_name)
  metadata_json = json.dumps(metadata, default=_json_serialize)
  log_data = {
    'kind': kind,
    'account': account,
    'performer': performer,
    'repository': repository,
    'ip': ip,
    'metadata_json': metadata_json,
    'datetime': timestamp
  }

  try:
    LogEntry.create(**log_data)
  except PeeweeException as ex:
    strict_logging_disabled = config.app_config.get('ALLOW_PULLS_WITHOUT_STRICT_LOGGING')
    if strict_logging_disabled and kind_name in ACTIONS_ALLOWED_WITHOUT_AUDIT_LOGGING:
      logger.exception('log_action failed', extra=({'exception': ex}).update(log_data))
    else:
      raise


def get_stale_logs_start_id(model):
  """ Gets the oldest log entry. """
  # TODO(LogMigrate): Remove the branch once we're back on LogEntry only.
  try:
    return (model.select(model.id).order_by(model.id).limit(1).tuples())[0][0]
  except IndexError:
    return None


def get_stale_logs_cutoff_id(cutoff_date, model):
  """ Gets the most recent ID created before the cutoff_date. """
  # TODO(LogMigrate): Remove the branch once we're back on LogEntry only.
  try:
    return (model.select(fn.Max(model.id)).where(model.datetime <= cutoff_date)
            .tuples())[0][0]
  except IndexError:
    return None


def get_stale_logs(start_id, end_id, model):
  """ Returns all the logs with IDs between start_id and end_id inclusively. """
  # TODO(LogMigrate): Remove the branch once we're back on LogEntry only.
  return model.select().where((model.id >= start_id), (model.id <= end_id))


def delete_stale_logs(start_id, end_id, model):
  """ Deletes all the logs with IDs between start_id and end_id. """
  # TODO(LogMigrate): Remove the branch once we're back on LogEntry only.
  model.delete().where((model.id >= start_id), (model.id <= end_id)).execute()


def get_repository_action_counts(repo, start_date):
  """ Returns the daily aggregated action counts for the given repository, starting at the given
      start date.
  """
  return RepositoryActionCount.select().where(RepositoryActionCount.repository == repo,
                                              RepositoryActionCount.date >= start_date)


def get_repositories_action_sums(repository_ids):
  """ Returns a map from repository ID to total actions within that repository in the last week. """
  if not repository_ids:
    return {}

  # Filter the join to recent entries only.
  last_week = datetime.now() - timedelta(weeks=1)
  tuples = (RepositoryActionCount.select(RepositoryActionCount.repository,
                                         fn.Sum(RepositoryActionCount.count))
            .where(RepositoryActionCount.repository << repository_ids)
            .where(RepositoryActionCount.date >= last_week)
            .group_by(RepositoryActionCount.repository).tuples())

  action_count_map = {}
  for record in tuples:
    action_count_map[record[0]] = record[1]

  return action_count_map