# -*- coding: utf-8 -*-
# Copyright (c) Alibaba, Inc. and its affiliates.

# Modified Based on the following original code.

# Registry class & build_from_config function partially modified from
# https://github.com/open-mmlab/mmcv/blob/master/mmcv/utils/registry.py
# Copyright 2018-2020 Open-MMLab. 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
import sys
import warnings

from scepter.modules.utils.config import dict_to_yaml

old_python_version = '3.6' in sys.version
if old_python_version:

    def deep_copy(obj):
        return obj
else:
    import copy

    def deep_copy(obj):
        return copy.deepcopy(obj)


def build_from_config(cfg, registry, logger=None, *args, **kwargs):
    """ Default builder function.

    Args:
        cfg (objective attribution): A set of objective attirbutions
            which contain parameters passes to target class or function.
            Must contains key 'type', indicates the target class or function name.
        registry (Registry): An registry to search target class or function.
        kwargs (dict, optional): Other params not in config dict.

    Returns:
        Target class object or object returned by invoking function.

    Raises:
        TypeError:
        KeyError:
        Exception:
    """
    from scepter.modules.utils.config import Config
    if not isinstance(cfg, Config):
        raise TypeError(f'config must be type dict, got {type(cfg)}')
    if not cfg.have('NAME'):
        raise KeyError(f'config must contain key NAME, got {cfg}')
    if not isinstance(registry, Registry):
        raise TypeError(
            f'registry must be type Registry, got {type(registry)}')

    cfg = deep_copy(cfg)
    req_type = cfg.get('NAME')
    if isinstance(req_type, str):
        req_type_entry = registry.get(req_type)
        if req_type_entry is None:
            raise KeyError(f'{req_type} not found in {registry.name} registry')

    if kwargs is not None:
        cfg._update_dict(kwargs)

    if inspect.isclass(req_type_entry):
        try:
            return req_type_entry(cfg, logger=logger, *args, **kwargs)
        except Exception as e:
            raise Exception(f'Failed to init class {req_type_entry}, with {e}')
    elif inspect.isfunction(req_type_entry):
        try:
            return req_type_entry(cfg, logger=logger, *args, **kwargs)
        except Exception as e:
            raise Exception(
                f'Failed to invoke function {req_type_entry}, with {e}')
    else:
        raise TypeError(
            f'type must be str or class, got {type(req_type_entry)}')


REGISTRY_LIST = []


class Registry(object):
    """ A registry maps key to classes or functions.

    Example:
         # >>> MODELS = Registry('MODELS')
         # >>> @MODELS.register_class()
         # >>> class ResNet(object):
         # >>>     pass
         # >>> config = Config(cfg_dict = {"NAME":"ResNet"})
         # >>> resnet = MODELS.build(config)
         # >>>
         # >>> import torchvision
         # >>> @MODELS.register_function("InceptionV3")
         # >>> def get_inception_v3(pretrained=False, progress=True):
         # >>>     return torchvision.model.inception_v3(pretrained=pretrained, progress=progress)
         # >>> config = Config(cfg_dict = {"NAME":"InceptionV3"})
         # >>> inception_v3 = MODELS.build(config)

    Args:
        name (str): Registry name.
        build_func (func, None): Instance construct function. Default is build_from_config.
        allow_types (tuple): Indicates how to construct the instance, by constructing class or invoking function.
    """
    def __init__(self,
                 name,
                 build_func=None,
                 common_para=None,
                 allow_types=('class', 'function')):
        self.name = name
        self.allow_types = allow_types
        self.class_map = {}
        self.func_map = {}
        self.common_para = common_para
        self.build_func = build_func or build_from_config
        REGISTRY_LIST.append(self)

    def get(self, req_type):
        return self.class_map.get(req_type) or self.func_map.get(req_type)

    def build(self, cfg, logger=None, *args, **kwargs):
        return self.build_func(cfg,
                               registry=self,
                               logger=logger,
                               *args,
                               **kwargs)

    def register_class(self, name=None):
        def _register(cls):
            if not inspect.isclass(cls):
                raise TypeError(f'Module must be type class, got {type(cls)}')
            if 'class' not in self.allow_types:
                raise TypeError(
                    f'Register {self.name} only allows type {self.allow_types}, got class'
                )
            module_name = name or cls.__name__
            if module_name in self.class_map:
                warnings.warn(
                    f'Class {module_name} already registered by {self.class_map[module_name]}, '
                    f'will be replaced by {cls}')
            self.class_map[module_name] = cls
            return cls

        return _register

    def register_function(self, name=None):
        def _register(func):
            if not inspect.isfunction(func):
                raise TypeError(
                    f'Registry must be type function, got {type(func)}')
            if 'function' not in self.allow_types:
                raise TypeError(
                    f'Registry {self.name} only allows type {self.allow_types}, got function'
                )
            func_name = name or func.__name__
            if func_name in self.class_map:
                warnings.warn(
                    f'Function {func_name} already registered by {self.func_map[func_name]}, '
                    f'will be replaced by {func}')
            self.func_map[func_name] = func
            return func

        return _register

    def _list(self):
        keys = sorted(list(self.class_map.keys()) + list(self.func_map.keys()))
        descriptions = []
        for key in keys:
            if key in self.class_map:
                descriptions.append(f'{key}: {self.class_map[key]}')
            else:
                descriptions.append(
                    f"{key}: <function '{self.func_map[key].__module__}.{self.func_map[key].__name__}'>"
                )
        return '\n'.join(descriptions)

    def __repr__(self):
        description = self._list()
        description = '\n'.join(['\t' + s for s in description.split('\n')])
        return f'{self.__class__.__name__} [{self.name}], \n' + description

    def get_config_template(self, name):
        common_yaml_str = ''
        if self.common_para is not None:
            common_yaml_str += 'The following para are used for this class.\n'
            common_yaml_str += dict_to_yaml('common_parameter',
                                            __class__.__name__,
                                            self.common_para,
                                            set_name=False)

        req_type_entry = self.get(name)
        if req_type_entry is None:
            raise KeyError(f'{name} not found in {self.name} registry')
        if inspect.isclass(req_type_entry):
            return req_type_entry.get_config_template() + common_yaml_str
        elif inspect.isfunction(req_type_entry):
            return '{} is a function!'.format(name)
        else:
            return 'Unsurport object type!'