# Copyright 2012 New Dream Network, LLC (DreamHost)
#
#    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 httplib
import socket

import eventlet
eventlet.monkey_patch()

import httplib2
from oslo.config import cfg
import six.moves.urllib.parse as urlparse
import webob

from neutron.agent.linux import daemon
from neutron.common import config
from neutron.common import utils
from neutron.i18n import _LE
from neutron.openstack.common import log as logging
from neutron import wsgi

LOG = logging.getLogger(__name__)


class UnixDomainHTTPConnection(httplib.HTTPConnection):
    """Connection class for HTTP over UNIX domain socket."""
    def __init__(self, host, port=None, strict=None, timeout=None,
                 proxy_info=None):
        httplib.HTTPConnection.__init__(self, host, port, strict)
        self.timeout = timeout

    def connect(self):
        self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
        if self.timeout:
            self.sock.settimeout(self.timeout)
        self.sock.connect(cfg.CONF.metadata_proxy_socket)


class NetworkMetadataProxyHandler(object):
    """Proxy AF_INET metadata request through Unix Domain socket.

    The Unix domain socket allows the proxy access resource that are not
    accessible within the isolated tenant context.
    """

    def __init__(self, network_id=None, router_id=None):
        self.network_id = network_id
        self.router_id = router_id

        if network_id is None and router_id is None:
            msg = _('network_id and router_id are None. One must be provided.')
            raise ValueError(msg)

    @webob.dec.wsgify(RequestClass=webob.Request)
    def __call__(self, req):
        LOG.debug("Request: %s", req)
        try:
            return self._proxy_request(req.remote_addr,
                                       req.method,
                                       req.path_info,
                                       req.query_string,
                                       req.body)
        except Exception:
            LOG.exception(_LE("Unexpected error."))
            msg = _('An unknown error has occurred. '
                    'Please try your request again.')
            return webob.exc.HTTPInternalServerError(explanation=unicode(msg))

    def _proxy_request(self, remote_address, method, path_info,
                       query_string, body):
        headers = {
            'X-Forwarded-For': remote_address,
        }

        if self.router_id:
            headers['X-Neutron-Router-ID'] = self.router_id
        else:
            headers['X-Neutron-Network-ID'] = self.network_id

        url = urlparse.urlunsplit((
            'http',
            '169.254.169.254',  # a dummy value to make the request proper
            path_info,
            query_string,
            ''))

        h = httplib2.Http()
        resp, content = h.request(
            url,
            method=method,
            headers=headers,
            body=body,
            connection_type=UnixDomainHTTPConnection)

        if resp.status == 200:
            LOG.debug(resp)
            LOG.debug(content)
            response = webob.Response()
            response.status = resp.status
            response.headers['Content-Type'] = resp['content-type']
            response.body = content
            return response
        elif resp.status == 400:
            return webob.exc.HTTPBadRequest()
        elif resp.status == 404:
            return webob.exc.HTTPNotFound()
        elif resp.status == 409:
            return webob.exc.HTTPConflict()
        elif resp.status == 500:
            msg = _(
                'Remote metadata server experienced an internal server error.'
            )
            LOG.debug(msg)
            return webob.exc.HTTPInternalServerError(explanation=unicode(msg))
        else:
            raise Exception(_('Unexpected response code: %s') % resp.status)


class ProxyDaemon(daemon.Daemon):
    def __init__(self, pidfile, port, network_id=None, router_id=None):
        uuid = network_id or router_id
        super(ProxyDaemon, self).__init__(pidfile, uuid=uuid)
        self.network_id = network_id
        self.router_id = router_id
        self.port = port

    def run(self):
        handler = NetworkMetadataProxyHandler(
            self.network_id,
            self.router_id)
        proxy = wsgi.Server('neutron-network-metadata-proxy')
        proxy.start(handler, self.port)
        proxy.wait()


def main():
    opts = [
        cfg.StrOpt('network_id',
                   help=_('Network that will have instance metadata '
                          'proxied.')),
        cfg.StrOpt('router_id',
                   help=_('Router that will have connected instances\' '
                          'metadata proxied.')),
        cfg.StrOpt('pid_file',
                   help=_('Location of pid file of this process.')),
        cfg.BoolOpt('daemonize',
                    default=True,
                    help=_('Run as daemon.')),
        cfg.IntOpt('metadata_port',
                   default=9697,
                   help=_("TCP Port to listen for metadata server "
                          "requests.")),
        cfg.StrOpt('metadata_proxy_socket',
                   default='$state_path/metadata_proxy',
                   help=_('Location of Metadata Proxy UNIX domain '
                          'socket'))
    ]

    cfg.CONF.register_cli_opts(opts)
    # Don't get the default configuration file
    cfg.CONF(project='neutron', default_config_files=[])
    config.setup_logging()
    utils.log_opt_values(LOG)
    proxy = ProxyDaemon(cfg.CONF.pid_file,
                        cfg.CONF.metadata_port,
                        network_id=cfg.CONF.network_id,
                        router_id=cfg.CONF.router_id)

    if cfg.CONF.daemonize:
        proxy.start()
    else:
        proxy.run()