# Copyright 2021 DeepMind Technologies Limited.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Download data required for training and evaluating models."""

import pathlib

from absl import app
from absl import flags
from absl import logging
from google.cloud import storage

Path = pathlib.Path


_BUCKET_NAME = 'deepmind-ogb-lsc'
_MAX_DOWNLOAD_ATTEMPTS = 5

FLAGS = flags.FLAGS

flags.DEFINE_enum('payload', None, ['data', 'models'],
                  'Download "data" or "models"?')
flags.DEFINE_string('task_root', None, 'Local task root directory')

# GCS_DATA_ROOT = Path('pcq/data')
# GCS_MODEL_ROOT = Path('pcq/models')

DATA_RELATIVE_PATHS = [
    'raw/data.csv.gz', 'preprocessed/smile_to_conformer.pkl',
    'k_fold_splits'
]


class DataCorruptionError(Exception):
  pass


def _get_gcs_root():
  return Path('pcq') / FLAGS.payload


def _get_gcs_bucket():
  storage_client = storage.Client.create_anonymous_client()
  return storage_client.bucket(_BUCKET_NAME)


def _write_blob_to_destination(blob, task_root, ignore_existing=True):
  """Write the blob."""
  logging.info("Copying blob: '%s'", blob.name)
  destination_path = Path(task_root) / Path(*Path(blob.name).parts[1:])
  logging.info("  ... to: '%s'", str(destination_path))
  if ignore_existing and destination_path.exists():
    return
  destination_path.parent.mkdir(parents=True, exist_ok=True)
  checksum = 'crc32c'
  for attempt in range(_MAX_DOWNLOAD_ATTEMPTS):
    try:
      blob.download_to_filename(destination_path.as_posix(), checksum=checksum)
    except storage.client.resumable_media.common.DataCorruption:
      pass
    else:
      break
  else:
    raise DataCorruptionError(f"Checksum ('{checksum}') for {blob.name} failed "
                              f'after {attempt + 1} attempts')


def main(unused_argv):
  bucket = _get_gcs_bucket()
  if FLAGS.payload == 'data':
    relative_paths = DATA_RELATIVE_PATHS
  else:
    relative_paths = (None,)
  for relative_path in relative_paths:
    if relative_path is None:
      relative_path = str(_get_gcs_root())
    else:
      relative_path = str(_get_gcs_root() / relative_path)
    logging.info("Copying relative path: '%s'", relative_path)
    blobs = bucket.list_blobs(prefix=relative_path)
    for blob in blobs:
      _write_blob_to_destination(blob, FLAGS.task_root)


if __name__ == '__main__':
  flags.mark_flag_as_required('payload')
  flags.mark_flag_as_required('task_root')
  app.run(main)
