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

#
#    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 functools
import os
import os.path
import sys
import base64
from lxml import etree
import re
import logging

from glance import client as glance_client
from heat.common import exception


SUCCESS = 0
FAILURE = 1


def catch_error(action):
    """Decorator to provide sensible default error handling for CLI actions."""
    def wrap(func):
        @functools.wraps(func)
        def wrapper(*arguments, **kwargs):
            try:
                ret = func(*arguments, **kwargs)
                return SUCCESS if ret is None else ret
            except exception.NotAuthorized:
                logging.error("Not authorized to make this request. Check " +
                      "your credentials (OS_USERNAME, OS_PASSWORD, " +
                      "OS_TENANT_NAME, OS_AUTH_URL and OS_AUTH_STRATEGY).")
                return FAILURE
            except exception.ClientConfigurationError:
                raise
            except Exception, e:
                options = arguments[0]
                if options.debug:
                    raise
                logging.error("Failed to %s. Got error:" % action)
                pieces = unicode(e).split('\n')
                for piece in pieces:
                    logging.error(piece)
                return FAILURE

        return wrapper
    return wrap


class LazyPluggable(object):
    """A pluggable backend loaded lazily based on some value."""

    def __init__(self, pivot, **backends):
        self.__backends = backends
        self.__pivot = pivot
        self.__backend = None

    def __get_backend(self):
        if not self.__backend:
            backend_name = 'sqlalchemy'
            backend = self.__backends[backend_name]
            if isinstance(backend, tuple):
                name = backend[0]
                fromlist = backend[1]
            else:
                name = backend
                fromlist = backend

            self.__backend = __import__(name, None, None, fromlist)
        return self.__backend

    def __getattr__(self, key):
        backend = self.__get_backend()
        return getattr(backend, key)