# Copyright (c) 2025 ByteDance Ltd. and/or its affiliates
#
# 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.
#
# Adapted from [VGGT-Long](https://github.com/DengKaiCQ/VGGT-Long)

import yaml


def load_config(path, default_path=None):
    """
    Loads config file.

    Args:
        path (str): path to config file.
        default_path (str, optional): whether to use default path. Defaults to None.

    Returns:
        cfg (dict): config dict.

    """
    # load configuration from per scene/dataset cfg.
    with open(path) as f:
        cfg_special = yaml.full_load(f)

    inherit_from = cfg_special.get("inherit_from")

    if inherit_from is not None:
        cfg = load_config(inherit_from, default_path)
    elif default_path is not None:
        with open(default_path) as f:
            cfg = yaml.full_load(f)
    else:
        cfg = dict()

    # merge per dataset cfg. and main cfg.
    update_recursive(cfg, cfg_special)

    return cfg


def update_recursive(dict1, dict2):
    """
    Update two config dictionaries recursively. dict1 get masked by dict2, and we retuen dict1.

    Args:
        dict1 (dict): first dictionary to be updated.
        dict2 (dict): second dictionary which entries should be used.
    """
    for k, v in dict2.items():
        if k not in dict1:
            dict1[k] = dict()
        if isinstance(v, dict):
            update_recursive(dict1[k], v)
        else:
            dict1[k] = v