# Copyright (c) 2019  PaddlePaddle Authors. 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.

import inspect

__all__ = ["Registry"]


class Registry(object):
    def __init__(self, name):
        self._name = name
        self._module_dict = dict()

    def __repr__(self):
        format_str = self.__class__.__name__ + '(name={}, items={})'.format(
            self._name, list(self._module_dict.keys()))
        return format_str

    @property
    def name(self):
        return self._name

    @property
    def module_dict(self):
        return self._module_dict

    def get(self, key):
        return self._module_dict.get(key, None)

    def _register_module(self, module_class):
        if not inspect.isclass(module_class):
            raise TypeError('module must be a class, but receive {}.'.format(
                type(module_class)))
        module_name = module_class.__name__
        if module_name in self._module_dict:
            raise KeyError('{} is already registered in {}.'.format(
                module_name, self.name))
        self._module_dict[module_name] = module_class

    def register(self, cls):
        self._register_module(cls)
        return cls