# Copyright 2015 Google LLC
#
# 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.

"""Client for interacting with the Google Cloud Storage API."""

from six.moves.urllib.parse import urlsplit

from google.auth.credentials import AnonymousCredentials

from google.api_core import page_iterator
from google.cloud._helpers import _LocalStack
from google.cloud.client import ClientWithProject
from google.cloud.exceptions import NotFound
from google.cloud.storage._http import Connection
from google.cloud.storage.batch import Batch
from google.cloud.storage.bucket import Bucket
from google.cloud.storage.blob import Blob


_marker = object()


class Client(ClientWithProject):
    """Client to bundle configuration needed for API requests.

    :type project: str or None
    :param project: the project which the client acts on behalf of. Will be
                    passed when creating a topic.  If not passed,
                    falls back to the default inferred from the environment.

    :type credentials: :class:`~google.auth.credentials.Credentials`
    :param credentials: (Optional) The OAuth2 Credentials to use for this
                        client. If not passed (and if no ``_http`` object is
                        passed), falls back to the default inferred from the
                        environment.

    :type _http: :class:`~requests.Session`
    :param _http: (Optional) HTTP object to make requests. Can be any object
                  that defines ``request()`` with the same interface as
                  :meth:`requests.Session.request`. If not passed, an
                  ``_http`` object is created that is bound to the
                  ``credentials`` for the current object.
                  This parameter should be considered private, and could
                  change in the future.

    :type client_info: :class:`~google.api_core.client_info.ClientInfo`
    :param client_info:
        The client info used to send a user-agent string along with API
        requests. If ``None``, then default info will be used. Generally,
        you only need to set this if you're developing your own library
        or partner tool.
    """

    SCOPE = (
        "https://www.googleapis.com/auth/devstorage.full_control",
        "https://www.googleapis.com/auth/devstorage.read_only",
        "https://www.googleapis.com/auth/devstorage.read_write",
    )
    """The scopes required for authenticating as a Cloud Storage consumer."""

    def __init__(self, project=_marker, credentials=None, _http=None, client_info=None):
        self._base_connection = None
        if project is None:
            no_project = True
            project = "<none>"
        else:
            no_project = False
        if project is _marker:
            project = None
        super(Client, self).__init__(
            project=project, credentials=credentials, _http=_http
        )
        if no_project:
            self.project = None
        self._connection = Connection(self, client_info=client_info)
        self._batch_stack = _LocalStack()

    @classmethod
    def create_anonymous_client(cls):
        """Factory: return client with anonymous credentials.

        .. note::

           Such a client has only limited access to "public" buckets:
           listing their contents and downloading their blobs.

        :rtype: :class:`google.cloud.storage.client.Client`
        :returns: Instance w/ anonymous credentials and no project.
        """
        client = cls(project="<none>", credentials=AnonymousCredentials())
        client.project = None
        return client

    @property
    def _connection(self):
        """Get connection or batch on the client.

        :rtype: :class:`google.cloud.storage._http.Connection`
        :returns: The connection set on the client, or the batch
                  if one is set.
        """
        if self.current_batch is not None:
            return self.current_batch
        else:
            return self._base_connection

    @_connection.setter
    def _connection(self, value):
        """Set connection on the client.

        Intended to be used by constructor (since the base class calls)
            self._connection = connection
        Will raise if the connection is set more than once.

        :type value: :class:`google.cloud.storage._http.Connection`
        :param value: The connection set on the client.

        :raises: :class:`ValueError` if connection has already been set.
        """
        if self._base_connection is not None:
            raise ValueError("Connection already set on client")
        self._base_connection = value

    def _push_batch(self, batch):
        """Push a batch onto our stack.

        "Protected", intended for use by batch context mgrs.

        :type batch: :class:`google.cloud.storage.batch.Batch`
        :param batch: newly-active batch
        """
        self._batch_stack.push(batch)

    def _pop_batch(self):
        """Pop a batch from our stack.

        "Protected", intended for use by batch context mgrs.

        :raises: IndexError if the stack is empty.
        :rtype: :class:`google.cloud.storage.batch.Batch`
        :returns: the top-most batch/transaction, after removing it.
        """
        return self._batch_stack.pop()

    @property
    def current_batch(self):
        """Currently-active batch.

        :rtype: :class:`google.cloud.storage.batch.Batch` or ``NoneType`` (if
                no batch is active).
        :returns: The batch at the top of the batch stack.
        """
        return self._batch_stack.top

    def get_service_account_email(self, project=None):
        """Get the email address of the project's GCS service account

        :type project: str
        :param project:
            (Optional) Project ID to use for retreiving GCS service account
            email address.  Defaults to the client's project.

        :rtype: str
        :returns: service account email address
        """
        if project is None:
            project = self.project
        path = "/projects/%s/serviceAccount" % (project,)
        api_response = self._base_connection.api_request(method="GET", path=path)
        return api_response["email_address"]

    def bucket(self, bucket_name, user_project=None):
        """Factory constructor for bucket object.

        .. note::
          This will not make an HTTP request; it simply instantiates
          a bucket object owned by this client.

        :type bucket_name: str
        :param bucket_name: The name of the bucket to be instantiated.

        :type user_project: str
        :param user_project: (Optional) the project ID to be billed for API
                             requests made via the bucket.

        :rtype: :class:`google.cloud.storage.bucket.Bucket`
        :returns: The bucket object created.
        """
        return Bucket(client=self, name=bucket_name, user_project=user_project)

    def batch(self):
        """Factory constructor for batch object.

        .. note::
          This will not make an HTTP request; it simply instantiates
          a batch object owned by this client.

        :rtype: :class:`google.cloud.storage.batch.Batch`
        :returns: The batch object created.
        """
        return Batch(client=self)

    def get_bucket(self, bucket_or_name):
        """API call: retrieve a bucket via a GET request.

        See
        https://cloud.google.com/storage/docs/json_api/v1/buckets/get

        Args:
            bucket_or_name (Union[ \
                :class:`~google.cloud.storage.bucket.Bucket`, \
                 str, \
            ]):
                The bucket resource to pass or name to create.

        Returns:
            google.cloud.storage.bucket.Bucket
                The bucket matching the name provided.

        Raises:
            google.cloud.exceptions.NotFound
                If the bucket is not found.

        Examples:
            Retrieve a bucket using a string.

            .. literalinclude:: snippets.py
                :start-after: [START get_bucket]
                :end-before: [END get_bucket]

            Get a bucket using a resource.

            >>> from google.cloud import storage
            >>> client = storage.Client()

            >>> # Set properties on a plain resource object.
            >>> bucket = client.get_bucket("my-bucket-name")

            >>> # Time passes. Another program may have modified the bucket
            ... # in the meantime, so you want to get the latest state.
            >>> bucket = client.get_bucket(bucket)  # API request.

        """

        bucket = None
        if isinstance(bucket_or_name, Bucket):
            bucket = bucket_or_name
        else:
            bucket = Bucket(self, name=bucket_or_name)

        bucket.reload(client=self)
        return bucket

    def lookup_bucket(self, bucket_name):
        """Get a bucket by name, returning None if not found.

        You can use this if you would rather check for a None value
        than catching an exception:

        .. literalinclude:: snippets.py
            :start-after: [START lookup_bucket]
            :end-before: [END lookup_bucket]

        :type bucket_name: str
        :param bucket_name: The name of the bucket to get.

        :rtype: :class:`google.cloud.storage.bucket.Bucket`
        :returns: The bucket matching the name provided or None if not found.
        """
        try:
            return self.get_bucket(bucket_name)
        except NotFound:
            return None

    def create_bucket(self, bucket_or_name, requester_pays=None, project=None):
        """API call: create a new bucket via a POST request.

        See
        https://cloud.google.com/storage/docs/json_api/v1/buckets/insert

        Args:
            bucket_or_name (Union[ \
                :class:`~google.cloud.storage.bucket.Bucket`, \
                 str, \
            ]):
                The bucket resource to pass or name to create.
            requester_pays (bool):
                Optional. Whether requester pays for API requests for this
                bucket and its blobs.
            project (str):
                Optional. the project under which the  bucket is to be created.
                If not passed, uses the project set on the client.

        Returns:
            google.cloud.storage.bucket.Bucket
                The newly created bucket.

        Raises:
            google.cloud.exceptions.Conflict
                If the bucket already exists.

        Examples:
            Create a bucket using a string.

            .. literalinclude:: snippets.py
                :start-after: [START create_bucket]
                :end-before: [END create_bucket]

            Create a bucket using a resource.

            >>> from google.cloud import storage
            >>> client = storage.Client()

            >>> # Set properties on a plain resource object.
            >>> bucket = storage.Bucket("my-bucket-name")
            >>> bucket.location = "europe-west6"
            >>> bucket.storage_class = "COLDLINE"

            >>> # Pass that resource object to the client.
            >>> bucket = client.create_bucket(bucket)  # API request.

        """

        bucket = None
        if isinstance(bucket_or_name, Bucket):
            bucket = bucket_or_name
        else:
            bucket = Bucket(self, name=bucket_or_name)

        if requester_pays is not None:
            bucket.requester_pays = requester_pays
        bucket.create(client=self, project=project)
        return bucket

    def download_blob_to_file(self, blob_or_uri, file_obj, start=None, end=None):
        """Download the contents of a blob object or blob URI into a file-like object.

        Args:
            blob_or_uri (Union[ \
            :class:`~google.cloud.storage.blob.Blob`, \
             str, \
            ]):
                The blob resource to pass or URI to download.
            file_obj (file):
                A file handle to which to write the blob's data.
            start (int):
                Optional. The first byte in a range to be downloaded.
            end (int):
                Optional. The last byte in a range to be downloaded.

        Examples:
            Download a blob using using a blob resource.

            >>> from google.cloud import storage
            >>> client = storage.Client()

            >>> bucket = client.get_bucket('my-bucket-name')
            >>> blob = storage.Blob('path/to/blob', bucket)

            >>> with open('file-to-download-to') as file_obj:
            >>>     client.download_blob_to_file(blob, file)  # API request.


            Download a blob using a URI.

            >>> from google.cloud import storage
            >>> client = storage.Client()

            >>> with open('file-to-download-to') as file_obj:
            >>>     client.download_blob_to_file(
            >>>         'gs://bucket_name/path/to/blob', file)


        """
        try:
            blob_or_uri.download_to_file(file_obj, client=self, start=start, end=end)
        except AttributeError:
            scheme, netloc, path, query, frag = urlsplit(blob_or_uri)
            if scheme != "gs":
                raise ValueError("URI scheme must be gs")
            bucket = Bucket(self, name=netloc)
            blob_or_uri = Blob(path, bucket)

            blob_or_uri.download_to_file(file_obj, client=self, start=start, end=end)

    def list_buckets(
        self,
        max_results=None,
        page_token=None,
        prefix=None,
        projection="noAcl",
        fields=None,
        project=None,
    ):
        """Get all buckets in the project associated to the client.

        This will not populate the list of blobs available in each
        bucket.

        .. literalinclude:: snippets.py
            :start-after: [START list_buckets]
            :end-before: [END list_buckets]

        This implements "storage.buckets.list".

        :type max_results: int
        :param max_results: Optional. The maximum number of buckets to return.

        :type page_token: str
        :param page_token:
            Optional. If present, return the next batch of buckets, using the
            value, which must correspond to the ``nextPageToken`` value
            returned in the previous response.  Deprecated: use the ``pages``
            property of the returned iterator instead of manually passing the
            token.

        :type prefix: str
        :param prefix: Optional. Filter results to buckets whose names begin
                       with this prefix.

        :type projection: str
        :param projection:
            (Optional) Specifies the set of properties to return. If used, must
            be 'full' or 'noAcl'. Defaults to 'noAcl'.

        :type fields: str
        :param fields:
            (Optional) Selector specifying which fields to include in a partial
            response. Must be a list of fields. For example to get a partial
            response with just the next page token and the language of each
            bucket returned: 'items/id,nextPageToken'

        :type project: str
        :param project: (Optional) the project whose buckets are to be listed.
                        If not passed, uses the project set on the client.

        :rtype: :class:`~google.api_core.page_iterator.Iterator`
        :raises ValueError: if both ``project`` is ``None`` and the client's
                            project is also ``None``.
        :returns: Iterator of all :class:`~google.cloud.storage.bucket.Bucket`
                  belonging to this project.
        """
        if project is None:
            project = self.project

        if project is None:
            raise ValueError("Client project not set:  pass an explicit project.")

        extra_params = {"project": project}

        if prefix is not None:
            extra_params["prefix"] = prefix

        extra_params["projection"] = projection

        if fields is not None:
            extra_params["fields"] = fields

        return page_iterator.HTTPIterator(
            client=self,
            api_request=self._connection.api_request,
            path="/b",
            item_to_value=_item_to_bucket,
            page_token=page_token,
            max_results=max_results,
            extra_params=extra_params,
        )


def _item_to_bucket(iterator, item):
    """Convert a JSON bucket to the native object.

    :type iterator: :class:`~google.api_core.page_iterator.Iterator`
    :param iterator: The iterator that has retrieved the item.

    :type item: dict
    :param item: An item to be converted to a bucket.

    :rtype: :class:`.Bucket`
    :returns: The next bucket in the page.
    """
    name = item.get("name")
    bucket = Bucket(iterator.client, name)
    bucket._set_properties(item)
    return bucket