# Copyright (c) 2012 OpenStack Foundation
#
#    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.
"""
Request Body limiting middleware.

"""


from oslo_config import cfg
import webob.dec
import webob.exc

from cinder.i18n import _
from cinder.openstack.common import log as logging
from cinder import wsgi


# Default request size is 112k
max_request_body_size_opt = cfg.IntOpt('osapi_max_request_body_size',
                                       default=114688,
                                       help='Max size for body of a request')

CONF = cfg.CONF
CONF.register_opt(max_request_body_size_opt)

LOG = logging.getLogger(__name__)


class LimitingReader(object):
    """Reader to limit the size of an incoming request."""
    def __init__(self, data, limit):
        """Initialize LimitingReader.

        :param data: Underlying data object
        :param limit: maximum number of bytes the reader should allow
        """
        self.data = data
        self.limit = limit
        self.bytes_read = 0

    def __iter__(self):
        for chunk in self.data:
            self.bytes_read += len(chunk)
            if self.bytes_read > self.limit:
                msg = _("Request is too large.")
                raise webob.exc.HTTPRequestEntityTooLarge(explanation=msg)
            else:
                yield chunk

    def read(self, i=None):
        result = self.data.read(i)
        self.bytes_read += len(result)
        if self.bytes_read > self.limit:
            msg = _("Request is too large.")
            raise webob.exc.HTTPRequestEntityTooLarge(explanation=msg)
        return result


class RequestBodySizeLimiter(wsgi.Middleware):
    """Add a 'cinder.context' to WSGI environ."""

    def __init__(self, *args, **kwargs):
        super(RequestBodySizeLimiter, self).__init__(*args, **kwargs)

    @webob.dec.wsgify(RequestClass=wsgi.Request)
    def __call__(self, req):
        if req.content_length > CONF.osapi_max_request_body_size:
            msg = _("Request is too large.")
            raise webob.exc.HTTPRequestEntityTooLarge(explanation=msg)
        if req.content_length is None and req.is_body_readable:
            limiter = LimitingReader(req.body_file,
                                     CONF.osapi_max_request_body_size)
            req.body_file = limiter
        return self.application
