# Copyright (c) 2023, NVIDIA CORPORATION.  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.

from typing import Union

from torch import nn
from torch.nn import init
from torch.nn.common_types import _size_2_t


class Conv2d(nn.Conv2d):

    """
    Conv2d layer with ResNet initialization:

    Reference: "Deep Residual Learning for Image Recognition" by He et al.
    https://arxiv.org/abs/1512.03385

    """

    def __init__(
        self,
        in_channels: int,
        out_channels: int,
        kernel_size: _size_2_t,
        stride: _size_2_t = 1,
        padding: Union[str, _size_2_t] = 0,
        dilation: _size_2_t = 1,
        groups: int = 1,
        bias: bool = True,
        padding_mode: str = 'zeros',
        device=None,
        dtype=None,
        weight_init: str = "default",
        bias_init: str = "default",
    ):

        super(Conv2d, self).__init__(
            in_channels=in_channels,
            out_channels=out_channels,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            groups=groups,
            bias=bias,
            padding_mode=padding_mode,
            device=device,
            dtype=dtype,
        )

        # Weight Init
        assert weight_init in ["default", "he_normal"]
        if weight_init == "he_normal":
            init.kaiming_normal_(self.weight)

        # Bias Init
        assert bias_init in ["default", "zeros"]
        if self.bias is not None:
            if bias_init == "zeros":
                init.zeros_(self.bias)