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

# Copyright 2011 OpenStack LLC.
# All Rights Reserved.
#
#    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.

"""
Exception definitions.
"""

class OpenStackException(Exception):
    """
    The base exception class for all exceptions this library raises.
    """
    def __init__(self, code, message=None, details=None):
        self.code = code
        self.message = message or self.__class__.message
        self.details = details

    def __str__(self):
        return "%s (HTTP %s)" % (self.message, self.code)


class BadRequest(OpenStackException):
    """
    HTTP 400 - Bad request: you sent some malformed data.
    """
    http_status = 400
    message = "Bad request"


class Unauthorized(OpenStackException):
    """
    HTTP 401 - Unauthorized: bad credentials.
    """
    http_status = 401
    message = "Unauthorized"


class Forbidden(OpenStackException):
    """
    HTTP 403 - Forbidden: your credentials don't give you access to this
    resource.
    """
    http_status = 403
    message = "Forbidden"


class NotFound(OpenStackException):
    """
    HTTP 404 - Not found
    """
    http_status = 404
    message = "Not found"


class OverLimit(OpenStackException):
    """
    HTTP 413 - Over limit: you're over the API limits for this time period.
    """
    http_status = 413
    message = "Over limit"


# NotImplemented is a python keyword.
class HTTPNotImplemented(OpenStackException):
    """
    HTTP 501 - Not Implemented: the server does not support this operation.
    """
    http_status = 501
    message = "Not Implemented"


# In Python 2.4 Exception is old-style and thus doesn't have a __subclasses__()
# so we can do this:
#     _code_map = dict((c.http_status, c)
#                      for c in OpenStackException.__subclasses__())
#
# Instead, we have to hardcode it:
_code_map = dict((c.http_status, c) for c in [BadRequest, Unauthorized,
                   Forbidden, NotFound, OverLimit, HTTPNotImplemented])


def from_response(response, body):
    """
    Return an instance of an OpenStackException or subclass
    based on an httplib2 response.

    Usage::

        resp, body = http.request(...)
        if resp.status != 200:
            raise exception_from_response(resp, body)
    """
    cls = _code_map.get(response.status, OpenStackException)
    if body:
        message = "n/a"
        details = "n/a"
        if hasattr(body, 'keys'):
            error = body[body.keys()[0]]
            message = error.get('message', None)
            details = error.get('details', None)
        return cls(code=response.status, message=message, details=details)
    else:
        return cls(code=response.status)