"""Dynamic Buffer Module."""

# Copyright (C) 2020 Intel Corporation
#
# 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 abc import ABC

from torch import Tensor, nn


class DynamicBufferModule(ABC, nn.Module):
    """Torch module that allows loading variables from the state dict even in the case of shape mismatch."""

    def get_tensor_attribute(self, attribute_name: str) -> Tensor:
        """Get attribute of the tensor given the name.

        Args:
            attribute_name (str): Name of the tensor

        Raises:
            ValueError: `attribute_name` is not a torch Tensor

        Returns:
            Tensor: Tensor attribute
        """
        attribute = self.__getattr__(attribute_name)
        if isinstance(attribute, Tensor):
            return attribute

        raise ValueError(f"Attribute with name '{attribute_name}' is not a torch Tensor")

    def _load_from_state_dict(self, state_dict: dict, prefix: str, *args):
        """Resizes the local buffers to match those stored in the state dict.

        Overrides method from parent class.

        Args:
          state_dict (dict): State dictionary containing weights
          prefix (str): Prefix of the weight file.
          *args:
        """
        persistent_buffers = {k: v for k, v in self._buffers.items() if k not in self._non_persistent_buffers_set}
        local_buffers = {k: v for k, v in persistent_buffers.items() if v is not None}

        for param in local_buffers.keys():
            for key in state_dict.keys():
                if key.startswith(prefix) and key[len(prefix) :].split(".")[0] == param:
                    if not local_buffers[param].shape == state_dict[key].shape:
                        attribute = self.get_tensor_attribute(param)
                        attribute.resize_(state_dict[key].shape)

        super()._load_from_state_dict(state_dict, prefix, *args)