# Copyright 2014 OpenStack Foundation
# 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.

__all__ = [
    'get_task',
    'unpack_task_input',
    'set_base_image_properties',
    'validate_location_uri',
    'get_image_data_iter',
]


from oslo_log import log as logging
from six.moves import urllib

from glance.common import exception
from glance.i18n import _, _LE

LOG = logging.getLogger(__name__)


def get_task(task_repo, task_id):
    """Gets a TaskProxy object.

    :param task_repo: TaskRepo object used to perform DB operations
    :param task_id: ID of the Task
    """
    task = None
    try:
        task = task_repo.get(task_id)
    except exception.NotFound:
        msg = _LE('Task not found for task_id %s') % task_id
        LOG.exception(msg)

    return task


def unpack_task_input(task):
    """Verifies and returns valid task input dictionary.

    :param task: Task domain object
    """
    task_type = task.type
    task_input = task.task_input

    if task_type == 'api_image_import':
        if not task_input:
            msg = _("Input to api_image_import task is empty.")
            raise exception.Invalid(msg)
        if 'image_id' not in task_input:
            msg = _("Missing required 'image_id' field")
            raise exception.Invalid(msg)
    else:
        for key in ["import_from", "import_from_format", "image_properties"]:
            if key not in task_input:
                msg = (_("Input does not contain '%(key)s' field") %
                       {"key": key})
                raise exception.Invalid(msg)

    return task_input


def set_base_image_properties(properties=None):
    """Sets optional base properties for creating Image.

    :param properties: Input dict to set some base properties
    """
    if isinstance(properties, dict) and len(properties) == 0:
        # TODO(nikhil): We can make these properties configurable while
        # implementing the pipeline logic for the scripts. The below shown
        # are placeholders to show that the scripts work on 'devstack'
        # environment.
        properties['disk_format'] = 'qcow2'
        properties['container_format'] = 'bare'


def validate_location_uri(location):
    """Validate location uri into acceptable format.

    :param location: Location uri to be validated
    """
    if not location:
        raise exception.BadStoreUri(_('Invalid location: %s') % location)

    elif location.startswith(('http://', 'https://')):
        return location

    # NOTE: file type uri is being avoided for security reasons,
    # see LP bug #942118 #1400966.
    elif location.startswith(("file:///", "filesystem:///")):
        msg = _("File based imports are not allowed. Please use a non-local "
                "source of image data.")
        # NOTE: raise BadStoreUri and let the encompassing block save the error
        # msg in the task.message.
        raise exception.BadStoreUri(msg)

    else:
        # TODO(nikhil): add other supported uris
        supported = ['http', ]
        msg = _("The given uri is not valid. Please specify a "
                "valid uri from the following list of supported uri "
                "%(supported)s") % {'supported': supported}
        raise urllib.error.URLError(msg)


def get_image_data_iter(uri):
    """Returns iterable object either for local file or uri

    :param uri: uri (remote or local) to the datasource we want to iterate

    Validation/sanitization of the uri is expected to happen before we get
    here.
    """
    # NOTE(flaper87): This is safe because the input uri is already
    # verified before the task is created.
    if uri.startswith("file://"):
        uri = uri.split("file://")[-1]
        # NOTE(flaper87): The caller of this function expects to have
        # an iterable object. FileObjects in python are iterable, therefore
        # we are returning it as is.
        # The file descriptor will be eventually cleaned up by the garbage
        # collector once its ref-count is dropped to 0. That is, when there
        # wont be any references pointing to this file.
        #
        # We're not using StringIO or other tools to avoid reading everything
        # into memory. Some images may be quite heavy.
        return open(uri, "r")

    return urllib.request.urlopen(uri)
