# -*- encoding: utf-8 -*-
#
# Copyright © 2013 Unitedstack Inc.
#
# Author: Jianing YANG (jianingy@unitedstack.com)
#
# 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.

"""A middleware that turns exceptions into parsable string. Inspired by
Cinder's faultwrapper
"""

import traceback
import webob

from heat.common import exception
from heat.openstack.common import log as logging
import heat.openstack.common.rpc.common as rpc_common

from heat.common import wsgi

logger = logging.getLogger(__name__)


class Fault(object):

    def __init__(self, error):
        self.error = error

    @webob.dec.wsgify(RequestClass=wsgi.Request)
    def __call__(self, req):
        if req.content_type == 'application/xml':
            serializer = wsgi.XMLResponseSerializer()
        else:
            serializer = wsgi.JSONResponseSerializer()
        resp = webob.Response(request=req)
        default_webob_exc = webob.exc.HTTPInternalServerError()
        resp.status_code = self.error.get('code', default_webob_exc.code)
        serializer.default(resp, self.error)
        return resp


class FaultWrapper(wsgi.Middleware):
    """Replace error body with something the client can parse."""

    error_map = {
        'AttributeError': webob.exc.HTTPBadRequest,
        'ValueError': webob.exc.HTTPBadRequest,
        'StackNotFound': webob.exc.HTTPNotFound,
        'ResourceNotFound': webob.exc.HTTPNotFound,
        'ResourceTypeNotFound': webob.exc.HTTPNotFound,
        'ResourceNotAvailable': webob.exc.HTTPNotFound,
        'PhysicalResourceNotFound': webob.exc.HTTPNotFound,
        'InvalidTenant': webob.exc.HTTPForbidden,
        'StackExists': webob.exc.HTTPConflict,
        'StackValidationFailed': webob.exc.HTTPBadRequest,
        'InvalidTemplateReference': webob.exc.HTTPBadRequest,
        'UnknownUserParameter': webob.exc.HTTPBadRequest,
        'RevertFailed': webob.exc.HTTPInternalServerError,
        'ServerBuildFailed': webob.exc.HTTPInternalServerError,
        'NotSupported': webob.exc.HTTPBadRequest,
        'MissingCredentialError': webob.exc.HTTPBadRequest,
        'UserParameterMissing': webob.exc.HTTPBadRequest,
    }

    def _error(self, ex):

        ex_type = ex.__class__.__name__

        if ex_type.endswith(rpc_common._REMOTE_POSTFIX):
            ex_type = ex_type[:-len(rpc_common._REMOTE_POSTFIX)]

        if isinstance(ex, exception.OpenstackException):
            # If the exception is an OpenstackException it is going to have a
            # translated Message object as the message, let's recreate it here
            message = (ex.message % ex.kwargs
                       if hasattr(ex, 'kwargs') else ex.message)
        else:
            message = ex.message

        trace = str(ex)
        if trace.find('\n') > -1:
            unused, trace = trace.split('\n', 1)
        else:
            trace = traceback.format_exc()

        webob_exc = self.error_map.get(ex_type,
                                       webob.exc.HTTPInternalServerError)

        error = {
            'code': webob_exc.code,
            'title': webob_exc.title,
            'explanation': webob_exc.explanation,
            'error': {
                'message': message,
                'type': ex_type,
                'traceback': trace,
            }
        }

        return error

    def process_request(self, req):
        try:
            return req.get_response(self.application)
        except Exception as exc:
            return req.get_response(Fault(self._error(exc)))