# Copyright 2016 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Purge old build artifacts to free up space.

Looks at build artifacts in gs://chromeos-releases and
gs://chromeos-image-archive. If they are old enough (and not protected for
some reason), they are moved to the matching backup bucket
gs://chromeos-releases-backup, or gs://chromeos-image-archive-backup.

Files in the backup buckets have a limited lifespan (currently 30 days), and are
deleted from there permanently after that time.

See go/cros-gs-cleanup-design for an overview.
"""

from __future__ import print_function

import datetime
import urlparse

from chromite.lib import commandline
from chromite.lib import cros_logging as logging
from chromite.lib import gs
from chromite.lib import purge_lib

# Roughly 6 months.
BUILD_CLEANUP = datetime.timedelta(weeks=6*4)


def GetParser():
  """Creates the argparse parser."""
  parser = commandline.ArgumentParser(
      description=__doc__,
      default_log_level='debug')

  parser.add_argument(
      '--dry-run', action='store_true', default=False,
      help='This is a dryrun, no files will be moved.')

  parser.add_argument(
      '--chromeos-releases', action='store_true', default=False,
      help='Cleanup files from gs://chromeos-releases.')

  parser.add_argument(
      '--chromeos-image-archive', action='store_true', default=False,
      help='Cleanup files from gs://chromeos-image-archive.')

  return parser


def Expire(ctx, url, dryrun):
  """Given a url, move it to the backup buckets.

  Args:
    ctx: GS context.
    url: Address of file to move.
    dryrun: Do we actually move the file?
  """
  logging.info('Expiring: %s', url)
  # Move gs://foo/some/file -> gs://foo-backup/some/file
  parts = urlparse.urlparse(url)
  expired_parts = list(parts)
  expired_parts[1] = parts.netloc + '-backup'
  target_url = urlparse.urlunparse(expired_parts)
  if dryrun:
    logging.notice('gsutil mv %s %s', url, target_url)
  else:
    try:
      ctx.Move(url, target_url)
    except Exception as e:
      # We can fail for lots of repeated random reasons.
      logging.warn('Move of "%s" failed, ignoring: "%s"', url, e)


def Examine(ctx, expired_cutoff, candidates, dryrun):
  """Given a list of candidates to move, move them to the backup buckets.

  Args:
    ctx: GS context.
    expired_cutoff: datetime.datetime of cutoff for expiring candidates.
    candidates: Iterable of gs.GSListResult objects.
    dryrun: Flag to turn on/off bucket updates.
  """
  for candidate in candidates:
    if candidate.creation_time < expired_cutoff:
      Expire(ctx, candidate.url, dryrun)


def main(argv):
  parser = GetParser()
  options = parser.parse_args(argv)
  options.Freeze()

  ctx = gs.GSContext()
  ctx.GetDefaultGSUtilBin()  # To force caching of gsutil pre-forking.

  now = datetime.datetime.now()
  expired_cutoff = now - BUILD_CLEANUP
  logging.info('Cutoff: %s', expired_cutoff)

  if options.chromeos_image_archive:
    archiveExcludes = purge_lib.LocateChromeosImageArchiveProtectedPrefixes(ctx)
    logging.info('Excluding:%s', '\n  '.join(archiveExcludes))

    archiveCandidates = purge_lib.ProduceFilteredCandidates(
        ctx, 'gs://chromeos-image-archive/', archiveExcludes, 2)
    Examine(ctx, expired_cutoff, archiveCandidates, dryrun=options.dry_run)

  if options.chromeos_releases:
    remote_branches = purge_lib.ListRemoteBranches()
    protected_branches = purge_lib.ProtectedBranchVersions(remote_branches)
    logging.info('Protected branch versions: %s',
                 '\n  '.join(protected_branches))

    releasesExcludes = purge_lib.LocateChromeosReleasesProtectedPrefixes(
        ctx, protected_branches)
    logging.info('Excluding:%s', '\n  '.join(releasesExcludes))

    releasesCandidates = purge_lib.ProduceFilteredCandidates(
        ctx, 'gs://chromeos-releases/', releasesExcludes, 3)
    Examine(ctx, expired_cutoff, releasesCandidates, dryrun=options.dry_run)

  return