# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright (c) 2013 TrilioData, Inc.
# All Rights Reserved.

import webob.dec
import webob.exc

from workloadmgr.api import wsgi
from workloadmgr.openstack.common import log as logging
from workloadmgr import utils
from workloadmgr import wsgi as base_wsgi


LOG = logging.getLogger(__name__)


class FaultWrapper(base_wsgi.Middleware):
    """Calls down the middleware stack, making exceptions into faults."""

    _status_to_type = {}

    @staticmethod
    def status_to_type(status):
        if not FaultWrapper._status_to_type:
            for clazz in utils.walk_class_hierarchy(webob.exc.HTTPError):
                FaultWrapper._status_to_type[clazz.code] = clazz
        return FaultWrapper._status_to_type.get(
            status, webob.exc.HTTPInternalServerError
        )()

    def _error(self, inner, req):
        LOG.exception(_("Caught error: %s"), str(inner))

        safe = getattr(inner, "safe", False)
        headers = getattr(inner, "headers", None)
        status = getattr(inner, "code", 500)
        if status is None:
            status = 500

        msg_dict = dict(url=req.url, status=status)
        LOG.info(_("%(url)s returned with HTTP %(status)d") % msg_dict)
        outer = self.status_to_type(status)
        if headers:
            outer.headers = headers
        # NOTE(giri): We leave the explanation empty here on
        # purpose. It could possibly have sensitive information
        # that should not be returned back to the user. See
        # bugs 868360 and 874472
        # NOTE(giri): However, it would be over-conservative and
        # inconsistent with the EC2 API to hide every exception,
        # including those that are safe to expose, see bug 1021373
        if safe:
            outer.explanation = "%s: %s" % (inner.__class__.__name__, str(inner))
        return wsgi.Fault(outer)

    @webob.dec.wsgify(RequestClass=wsgi.Request)
    def __call__(self, req):
        try:
            return req.get_response(self.application)
        except Exception as ex:
            return self._error(ex, req)