# Copyright 2018 Red Hat
#
#    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.
from __future__ import absolute_import


class TobikoException(Exception):
    """Base Tobiko Exception.

    To use this class, inherit from it and define attribute 'message' string.
    If **properties parameters is given, then it will format message string
    using properties as key-word arguments.

    Example:

        class MyException(TobikoException):
            message = "This exception occurred because of {reason}"

        try:
            raise MyException(reason="something went wrong")
        except MyException as ex:

            # It should print:
            #   This exception occurred because of something went wrong
            print(ex)

            # It should print:
            #   something went wrong
            print(ex.reason)

    :attribute message: the message to be printed out.
    """

    message = None

    def __init__(self, message=None, **properties):
        # pylint: disable=exception-message-attribute
        message = message or self.message or "unknown reason"
        if properties:
            message = message.format(**properties)
        self.message = message
        self._properties = properties or {}
        super(TobikoException, self).__init__(message)

    def __getattr__(self, name):
        try:
            return self._properties[name]
        except KeyError:
            msg = ("{!r} object has no attribute {!r}").format(self, name)
            raise AttributeError(msg)

    def __repr__(self):
        return "{class_name}({message!r})".format(
            class_name=type(self).__name__,
            message=self.message)