# 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.

import hashlib

"""
Download an image with the Image service.

For a full guide see
http://developer.openstack.org/sdks/python/openstacksdk/users/guides/image.html
"""


def download_image_stream(conn):
    print("Download Image via streaming:")

    # Find the image you would like to download.
    image = conn.image.find_image("myimage")

    # As the actual download now takes place outside of the library
    # and in your own code, you are now responsible for checking
    # the integrity of the data. Create an MD5 has to be computed
    # after all of the data has been consumed.
    md5 = hashlib.md5()

    with open("myimage.qcow2", "wb") as local_image:
        response = conn.image.download_image(image, stream=True)

        # Read only 1024 bytes of memory at a time until
        # all of the image data has been consumed.
        for chunk in response.iter_content(chunk_size=1024):

            # With each chunk, add it to the hash to be computed.
            md5.update(chunk)

            local_image.write(chunk)

        # Now that you've consumed all of the data the response gave you,
        # ensure that the checksums of what the server offered and
        # what you downloaded are the same.
        if response.headers["Content-MD5"] != md5.hexdigest():
            raise Exception("Checksum mismatch in downloaded content")


def download_image(conn):
    print("Download Image:")

    # Find the image you would like to download.
    image = conn.image.find_image("myimage")

    with open("myimage.qcow2", "w") as local_image:
        response = conn.image.download_image(image)

        # Response will contain the entire contents of the Image.
        local_image.write(response)

Add image download example