# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserve.
#
# 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 os
import yaml

__all__ = ['get_config']


class AttrDict(dict):
    def __getattr__(self, key):
        try:
            return self[key]
        except KeyError:
            raise AttributeError(key)

    def __setattr__(self, key, value):
        if key in self.__dict__:
            self.__dict__[key] = value
        else:
            self[key] = value


def create_attr_dict(yaml_config):
    from ast import literal_eval
    for key, value in yaml_config.items():
        if type(value) is dict:
            yaml_config[key] = value = AttrDict(value)
        if isinstance(value, str):
            try:
                value = literal_eval(value)
            except BaseException:
                pass
        if isinstance(value, AttrDict):
            create_attr_dict(yaml_config[key])
        else:
            yaml_config[key] = value


def parse_config(cfg_file):
    """Load a config file into AttrDict"""
    with open(cfg_file, 'r') as fopen:
        yaml_config = AttrDict(yaml.load(fopen, Loader=yaml.SafeLoader))
    create_attr_dict(yaml_config)
    return yaml_config


def override(dl, ks, v):
    """
    Recursively replace dict of list
    Args:
        dl(dict or list): dict or list to be replaced
        ks(list): list of keys
        v(str): value to be replaced
    """

    def str2num(v):
        try:
            return eval(v)
        except Exception:
            return v

    assert isinstance(dl, (list, dict)), ("{} should be a list or a dict")
    assert len(ks) > 0, ('lenght of keys should larger than 0')
    if isinstance(dl, list):
        k = str2num(ks[0])
        if len(ks) == 1:
            assert k < len(dl), ('index({}) out of range({})'.format(k, dl))
            dl[k] = str2num(v)
        else:
            override(dl[k], ks[1:], v)
    else:
        if len(ks) == 1:
            assert ks[0] in dl, ('{} is not exist in {}'.format(ks[0], dl))
            dl[ks[0]] = str2num(v)
        else:
            override(dl[ks[0]], ks[1:], v)


def override_config(config, options=None):
    """
    Recursively override the config
    Args:
        config(dict): dict to be replaced
        options(list): list of pairs(key0.key1.idx.key2=value)
            such as: [
                'topk=2',
                'VALID.transforms.1.ResizeImage.resize_short=300'
            ]
    Returns:
        config(dict): replaced config
    """
    if options is not None:
        for opt in options:
            assert isinstance(opt,
                              str), ("option({}) should be a str".format(opt))
            assert "=" in opt, (
                "option({}) should contain a ="
                "to distinguish between key and value".format(opt))
            pair = opt.split('=')
            assert len(pair) == 2, ("there can be only a = in the option")
            key, value = pair
            keys = key.split('.')
            override(config, keys, value)

    return config


def get_config(fname, overrides=None, show=True):
    """
    Read config from file
    """
    assert os.path.exists(fname), ('config file({}) is not exist'.format(fname))
    config = parse_config(fname)
    override_config(config, overrides)

    return config