import logging
import json
import time

from datetime import timedelta, datetime
from gzip import GzipFile
from tempfile import SpooledTemporaryFile

import features
from app import app, storage
from data.database import UseThenDisconnect, LogEntry, LogEntry2
from data.model.log import (get_stale_logs, get_stale_logs_start_id,
                            get_stale_logs_cutoff_id, delete_stale_logs)
from data.userfiles import DelegateUserfiles
from util.locking import GlobalLock, LockNotAcquiredException
from util.log import logfile_path
from util.streamingjsonencoder import StreamingJSONEncoder
from workers.worker import Worker

logger = logging.getLogger(__name__)

JSON_MIMETYPE = 'application/json'
STALE_AFTER = timedelta(days=30)
MIN_LOGS_PER_ROTATION = 10000
MEMORY_TEMPFILE_SIZE = 12 * 1024 * 1024

WORKER_FREQUENCY = app.config.get('ACTION_LOG_ROTATION_FREQUENCY', 60 * 60 * 12)
SAVE_PATH = app.config.get('ACTION_LOG_ARCHIVE_PATH')
SAVE_LOCATION = app.config.get('ACTION_LOG_ARCHIVE_LOCATION')

class LogRotateWorker(Worker):
  """ Worker used to rotate old logs out the database and into storage. """
  def __init__(self):
    super(LogRotateWorker, self).__init__()
    self.add_operation(self._archive_logs, WORKER_FREQUENCY)

  def _archive_logs(self):
    # TODO(LogMigrate): Remove the branch once we're back on LogEntry only.
    models = [LogEntry, LogEntry2]
    for model in models:
      self._archive_logs_for_model(model)

  def _archive_logs_for_model(self, model):
    logger.debug('Attempting to rotate log entries')

    with UseThenDisconnect(app.config):
      cutoff_date = datetime.now() - STALE_AFTER
      cutoff_id = get_stale_logs_cutoff_id(cutoff_date, model)
      if cutoff_id is None:
        logger.warning('Failed to find cutoff id')
        return

    logs_archived = True
    while logs_archived:
      try:
        with GlobalLock('ACTION_LOG_ROTATION'):
          logs_archived = self._perform_archiving(cutoff_id, model)
      except LockNotAcquiredException:
        return

  def _perform_archiving(self, cutoff_id, model):
    save_location = SAVE_LOCATION
    if not save_location:
      # Pick the *same* save location for all instances. This is a fallback if
      # a location was not configured.
      save_location = storage.locations[0]

    log_archive = DelegateUserfiles(app, storage, save_location, SAVE_PATH)

    with UseThenDisconnect(app.config):
      start_id = get_stale_logs_start_id(model)

      if start_id is None:
        logger.warning('Failed to find start id')
        return False

      logger.debug('Found starting ID %s and cutoff ID %s', start_id, cutoff_id)

      approx_count = cutoff_id - start_id
      if approx_count < MIN_LOGS_PER_ROTATION:
        logger.debug('Not enough stale logs to warrant rotation (approx %d)', approx_count)
        return False

      end_id = start_id + MIN_LOGS_PER_ROTATION
      logs = [log_dict(log) for log in get_stale_logs(start_id, end_id, model)]

    logger.debug('Archiving logs from IDs %s to %s', start_id, end_id)
    with SpooledTemporaryFile(MEMORY_TEMPFILE_SIZE) as tempfile:
      with GzipFile('temp_action_log_rotate', fileobj=tempfile, compresslevel=1) as zipstream:
        for chunk in StreamingJSONEncoder().iterencode(logs):
          zipstream.write(chunk)

      tempfile.seek(0)
      filename = '%d-%d-%s.txt.gz' % (start_id, end_id, model.__name__.lower())
      log_archive.store_file(tempfile, JSON_MIMETYPE, content_encoding='gzip',
                             file_id=filename)
      logger.debug('Finished archiving logs from IDs %s to %s', start_id, end_id)

    with UseThenDisconnect(app.config):
      logger.debug('Deleting logs from IDs %s to %s', start_id, end_id)
      delete_stale_logs(start_id, end_id, model)

    return True


def log_dict(log):
  """ Pretty prints a LogEntry in JSON. """
  return {'kind_id': log.kind_id,
          'account_id': log.account_id,
          'performer_id': log.performer_id,
          'repository_id': log.repository_id,
          'datetime': str(log.datetime),
          'ip': str(log.ip),
          'metadata_json': json.loads(str(log.metadata_json))}


def main():
  logging.config.fileConfig(logfile_path(debug=False), disable_existing_loggers=False)

  if not features.ACTION_LOG_ROTATION or None in [SAVE_PATH, SAVE_LOCATION]:
    logger.debug('Action log rotation worker not enabled; skipping')
    while True:
      time.sleep(100000)

  worker = LogRotateWorker()
  worker.start()


if __name__ == "__main__":
  main()