# Copyright 2018 The Lucid Authors. All Rights Reserved.
#
# 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
#
#     http://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.
# ==============================================================================

"""Methods for writing bytes to arbitrary destinations.

This module takes data and a URL, and attempts to save that data at that URL.

"""

from __future__ import absolute_import, division, print_function

import os
import logging
from contextlib import contextmanager
from urllib.parse import urlparse
from tensorflow.io import gfile

from lucid.misc.io.scoping import scope_url

log = logging.getLogger(__name__)


def _supports_make_dirs(path):
    """Whether this path implies a storage system that supports and requires
    intermediate directories to be created explicitly."""
    prefixes = ["/bigstore", "gs://"]
    return not any(path.startswith(prefix) for prefix in prefixes)


def _supports_binary_writing(path):
    """Whether this path implies a storage system that supports and requires
    intermediate directories to be created explicitly."""
    return not path.startswith("/bigstore")


def _write_to_path(data, path, mode="wb"):
    with write_handle(path, mode) as handle:
        handle.write(data)


# Public functions


def write(data, url, mode="wb"):
    if urlparse(url).scheme in ("http", "https"):
        message = "Writing to remote URL (%s) is not yet supported."
        raise ValueError(message, url)

    _write_to_path(data, url, mode=mode)


@contextmanager
def write_handle(path, mode=None):
    path = scope_url(path)

    if _supports_make_dirs(path):
        gfile.makedirs(os.path.dirname(path))

    if mode is None:
        if _supports_binary_writing(path):
            mode = "wb"
        else:
            mode = "w"

    handle = gfile.GFile(path, mode)
    yield handle
    handle.close()
