#!/usr/bin/env python
# -*- encoding: utf-8 -*-
#
# Copyright © 2012 eNovance <licensing@enovance.com>
#
# Author: Julien Danjou <julien@danjou.info>
#
# 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.


"""
Ceilometer Middleware for Swift Proxy

Configuration:

In /etc/swift/proxy-server.conf on the main pipeline add "ceilometer" just
before "proxy-server" and add the following filter in the file:

[filter:ceilometer]
use = egg:ceilometer#swift

# Some optional configuration
# this allow to publish additional metadata
metadata_headers = X-TEST
"""

from __future__ import absolute_import

from oslo.config import cfg
from swift.common.utils import split_path
import webob

REQUEST = webob
try:
    # Swift >= 1.7.5
    import swift.common.swob
    REQUEST = swift.common.swob
except ImportError:
    pass

try:
    # Swift > 1.7.5 ... module exists but doesn't contain class.
    from swift.common.utils import InputProxy
except ImportError:
    # Swift <= 1.7.5 ... module exists and has class.
    from swift.common.middleware.proxy_logging import InputProxy

from ceilometer import counter
from ceilometer.openstack.common import context
from ceilometer.openstack.common import timeutils
from ceilometer import pipeline
from ceilometer import publisher
from ceilometer import service
from ceilometer import transformer


class CeilometerMiddleware(object):
    """
    Ceilometer middleware used for counting requests.
    """

    def __init__(self, app, conf):
        self.app = app

        self.metadata_headers = [h.strip().replace('-', '_').lower()
                                 for h in conf.get(
                                     "metadata_headers",
                                     "").split(",") if h.strip()]

        service.prepare_service()

        self.pipeline_manager = pipeline.setup_pipeline(
            transformer.TransformerExtensionManager(
                'ceilometer.transformer',
            ),
            publisher.PublisherExtensionManager(
                'ceilometer.publisher',
            ),
        )

    def __call__(self, env, start_response):
        start_response_args = [None]
        input_proxy = InputProxy(env['wsgi.input'])
        env['wsgi.input'] = input_proxy

        def my_start_response(status, headers, exc_info=None):
            start_response_args[0] = (status, list(headers), exc_info)

        def iter_response(iterable):
            if start_response_args[0]:
                start_response(*start_response_args[0])
            bytes_sent = 0
            try:
                for chunk in iterable:
                    if chunk:
                        bytes_sent += len(chunk)
                    yield chunk
            finally:
                self.publish_counter(env,
                                     input_proxy.bytes_received,
                                     bytes_sent)

        try:
            iterable = self.app(env, my_start_response)
        except Exception:
            self.publish_counter(env, input_proxy.bytes_received, 0)
            raise
        else:
            return iter_response(iterable)

    def publish_counter(self, env, bytes_received, bytes_sent):
        req = REQUEST.Request(env)
        version, account, container, obj = split_path(req.path, 1, 4, True)
        now = timeutils.utcnow().isoformat()

        resource_metadata = {
            "path": req.path,
            "version": version,
            "container": container,
            "object": obj,
        }

        for header in self.metadata_headers:
            if header.upper() in req.headers:
                resource_metadata['http_header_%s' % header] = req.headers.get(
                    header.upper())

        with pipeline.PublishContext(
                context.get_admin_context(),
                cfg.CONF.counter_source,
                self.pipeline_manager.pipelines,
        ) as publisher:
            if bytes_received:
                publisher([counter.Counter(
                    name='storage.objects.incoming.bytes',
                    type=counter.TYPE_DELTA,
                    unit='B',
                    volume=bytes_received,
                    user_id=env.get('HTTP_X_USER_ID'),
                    project_id=env.get('HTTP_X_TENANT_ID'),
                    resource_id=account.partition('AUTH_')[2],
                    timestamp=now,
                    resource_metadata=resource_metadata)])

            if bytes_sent:
                publisher([counter.Counter(
                    name='storage.objects.outgoing.bytes',
                    type=counter.TYPE_DELTA,
                    unit='B',
                    volume=bytes_sent,
                    user_id=env.get('HTTP_X_USER_ID'),
                    project_id=env.get('HTTP_X_TENANT_ID'),
                    resource_id=account.partition('AUTH_')[2],
                    timestamp=now,
                    resource_metadata=resource_metadata)])

            # publish the event for each request
            # request method will be recorded in the metadata
            resource_metadata['method'] = req.method.lower()
            publisher([counter.Counter(
                name='storage.api.request',
                type=counter.TYPE_DELTA,
                unit='request',
                volume=1,
                user_id=env.get('HTTP_X_USER_ID'),
                project_id=env.get('HTTP_X_TENANT_ID'),
                resource_id=account.partition('AUTH_')[2],
                timestamp=now,
                resource_metadata=resource_metadata)])


def filter_factory(global_conf, **local_conf):
    conf = global_conf.copy()
    conf.update(local_conf)

    def ceilometer_filter(app):
        return CeilometerMiddleware(app, conf)
    return ceilometer_filter