# "Densely Connected Convolutional Networks" <https://arxiv.org/pdf/1608.06993.pdf>
# Reference: https://github.com/pytorch/vision/blob/main/torchvision/models/densenet.py

import math
import torch
import torch.nn as nn
import torch.nn.functional as F
import torch.utils.checkpoint as cp
from collections import OrderedDict


def _bn_function_factory(norm, relu, conv):
    def bn_function(*inputs):
        concated_features = torch.cat(inputs, 1)
        bottleneck_output = conv(relu(norm(concated_features)))
        return bottleneck_output

    return bn_function


class _DenseLayer(nn.Module):
    def __init__(self, num_input_features, growth_rate, bn_size, drop_rate, efficient=False):
        super(_DenseLayer, self).__init__()
        self.add_module("norm1", nn.BatchNorm2d(num_input_features)),
        self.add_module("relu1", nn.ReLU(inplace=True)),
        self.add_module(
            "conv1",
            nn.Conv2d(
                num_input_features,
                bn_size * growth_rate,
                kernel_size=1,
                stride=1,
                bias=False,
            ),
        ),
        self.add_module("norm2", nn.BatchNorm2d(bn_size * growth_rate)),
        self.add_module("relu2", nn.ReLU(inplace=True)),
        self.add_module(
            "conv2",
            nn.Conv2d(
                bn_size * growth_rate,
                growth_rate,
                kernel_size=3,
                stride=1,
                padding=1,
                bias=False,
            ),
        ),
        self.drop_rate = drop_rate
        self.efficient = efficient

    def forward(self, *prev_features):
        bn_function = _bn_function_factory(self.norm1, self.relu1, self.conv1)
        if self.efficient and any(prev_feature.requires_grad for prev_feature in prev_features):
            bottleneck_output = cp.checkpoint(bn_function, *prev_features)
        else:
            bottleneck_output = bn_function(*prev_features)
        new_features = self.conv2(self.relu2(self.norm2(bottleneck_output)))
        if self.drop_rate > 0:
            new_features = F.dropout(new_features, p=self.drop_rate, training=self.training)
        return new_features


class _Transition(nn.Sequential):
    def __init__(self, num_input_features, num_output_features):
        super(_Transition, self).__init__()
        self.add_module("norm", nn.BatchNorm2d(num_input_features))
        self.add_module("relu", nn.ReLU(inplace=True))
        self.add_module(
            "conv",
            nn.Conv2d(
                num_input_features,
                num_output_features,
                kernel_size=1,
                stride=1,
                bias=False,
            ),
        )
        self.add_module("pool", nn.AvgPool2d(kernel_size=2, stride=2))


class _DenseBlock(nn.Module):
    def __init__(
        self,
        num_layers,
        num_input_features,
        bn_size,
        growth_rate,
        drop_rate,
        efficient=False,
    ):
        super(_DenseBlock, self).__init__()
        for i in range(num_layers):
            layer = _DenseLayer(
                num_input_features + i * growth_rate,
                growth_rate=growth_rate,
                bn_size=bn_size,
                drop_rate=drop_rate,
                efficient=efficient,
            )
            self.add_module("denselayer%d" % (i + 1), layer)

    def forward(self, init_features):
        features = [init_features]
        for name, layer in self.named_children():
            new_features = layer(*features)
            features.append(new_features)
        return torch.cat(features, 1)


class DenseNet_(nn.Module):
    r"""Densenet-BC model class, based on
    `"Densely Connected Convolutional Networks" <https://arxiv.org/pdf/1608.06993.pdf>`
    Args:
        growth_rate (int) - how many filters to add each layer (`k` in paper)
        block_config (list of 3 or 4 ints) - how many layers in each pooling block
        num_init_features (int) - the number of filters to learn in the first convolution layer
        compression (float) - a value between 0 and 1
        bn_size (int) - multiplicative factor for number of bottle neck layers
            (i.e. bn_size * k features in the bottleneck layer)
        drop_rate (float) - dropout rate after each dense layer
        num_classes (int) - number of classification classes
        small_inputs (bool) - set to True if images are 32x32. Otherwise assumes images are larger.
        efficient (bool) - set to True to use checkpointing. Much more memory efficient, but slower.
    """

    def __init__(
        self,
        growth_rate=12,
        block_config=(16, 16, 16),
        num_init_features=24,
        compression=0.5,
        bn_size=4,
        drop_rate=0,
        num_classes=10,
        small_inputs=True,
        efficient=False,
    ):

        super(DenseNet_, self).__init__()
        assert 0 < compression <= 1, "compression of densenet should be between 0 and 1"

        # First convolution
        if small_inputs:
            self.features = nn.Sequential(
                OrderedDict(
                    [
                        (
                            "conv0",
                            nn.Conv2d(
                                3,
                                num_init_features,
                                kernel_size=3,
                                stride=1,
                                padding=1,
                                bias=False,
                            ),
                        ),
                    ]
                )
            )
        else:
            self.features = nn.Sequential(
                OrderedDict(
                    [
                        (
                            "conv0",
                            nn.Conv2d(
                                3,
                                num_init_features,
                                kernel_size=7,
                                stride=2,
                                padding=3,
                                bias=False,
                            ),
                        ),
                    ]
                )
            )
            self.features.add_module("norm0", nn.BatchNorm2d(num_init_features))
            self.features.add_module("relu0", nn.ReLU(inplace=True))
            self.features.add_module(
                "pool0",
                nn.MaxPool2d(kernel_size=3, stride=2, padding=1, ceil_mode=False),
            )

        # Each denseblock
        num_features = num_init_features
        for i, num_layers in enumerate(block_config):
            block = _DenseBlock(
                num_layers=num_layers,
                num_input_features=num_features,
                bn_size=bn_size,
                growth_rate=growth_rate,
                drop_rate=drop_rate,
                efficient=efficient,
            )
            self.features.add_module("denseblock%d" % (i + 1), block)
            num_features = num_features + num_layers * growth_rate
            if i != len(block_config) - 1:
                trans = _Transition(
                    num_input_features=num_features,
                    num_output_features=int(num_features * compression),
                )
                self.features.add_module("transition%d" % (i + 1), trans)
                num_features = int(num_features * compression)

        # Final batch norm
        self.features.add_module("norm_final", nn.BatchNorm2d(num_features))

        # Linear layer
        self.classifier = nn.Linear(num_features, num_classes)

        # Initialization
        for name, param in self.named_parameters():
            if "conv" in name and "weight" in name:
                n = param.size(0) * param.size(2) * param.size(3)
                param.data.normal_().mul_(math.sqrt(2.0 / n))
            elif "norm" in name and "weight" in name:
                param.data.fill_(1)
            elif "norm" in name and "bias" in name:
                param.data.fill_(0)
            elif "classifier" in name and "bias" in name:
                param.data.fill_(0)

    def forward(self, x):
        features = self.features(x)
        out = F.relu(features, inplace=True)
        out = F.adaptive_avg_pool2d(out, (1, 1))
        out = torch.flatten(out, 1)
        out = self.classifier(out)
        return out


def _densenet(
    growth_rate: int,
    block_config,
    num_init_features: int,
    **kwargs,
) -> DenseNet_:
    if "num_init_features" in kwargs:
        num_init_features = kwargs["num_init_features"]

    model = DenseNet_(growth_rate, block_config, num_init_features, **kwargs)
    return model


def densenet121(**kwargs) -> DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 24, 16), num_init_features=64, **kwargs)


def densenet161(**kwargs) -> DenseNet_:
    return _densenet(growth_rate=48, block_config=(6, 12, 36, 24), num_init_features=96, **kwargs)


def densenet169(**kwargs) -> DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 32, 32), num_init_features=64, **kwargs)


def densenet201(**kwargs) -> DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 48, 32), num_init_features=64, **kwargs)


VALID_MODELS = {
    "densenet121": densenet121,
    "densenet161": densenet161,
    "densenet169": densenet169,
    "densenet201": densenet201,
}


def DenseNet(model_name: str, **kwargs) -> DenseNet_:
    if model_name not in VALID_MODELS:
        raise ValueError(f"Invalid model name: {model_name}")
    return VALID_MODELS[model_name](**kwargs)

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class _DenseLayer(nn.Module):

    def __init__(self, num_input_features, growth_rate, bn_size, drop_rate,
        efficient=False):
        super(_DenseLayer, self).__init__()
        self.add_module('norm1', nn.BatchNorm2d(num_input_features)),
        self.add_module('relu1', nn.ReLU(inplace=True)),
        self.add_module('conv1', nn.Conv2d(num_input_features, bn_size *
            growth_rate, kernel_size=1, stride=1, bias=False)),
        self.add_module('norm2', nn.BatchNorm2d(bn_size * growth_rate)),
        self.add_module('relu2', nn.ReLU(inplace=True)),
        self.add_module('conv2', nn.Conv2d(bn_size * growth_rate,
            growth_rate, kernel_size=3, stride=1, padding=1, bias=False)),
        self.drop_rate = drop_rate
        self.efficient = efficient

    def forward(self, *prev_features):
        bn_function = _bn_function_factory(self.norm1, self.relu1, self.conv1)
        if self.efficient and any(prev_feature.requires_grad for
            prev_feature in prev_features):
            bottleneck_output = cp.checkpoint(bn_function, *prev_features)
        else:
            bottleneck_output = bn_function(*prev_features)
        new_features = self.conv2(self.relu2(self.norm2(bottleneck_output)))
        if self.drop_rate > 0:
            new_features = F.dropout(new_features, p=self.drop_rate,
                training=self.training)
        return new_features


class _Transition(nn.Sequential):

    def __init__(self, num_input_features, num_output_features):
        super(_Transition, self).__init__()
        self.add_module('norm', nn.BatchNorm2d(num_input_features))
        self.add_module('relu', nn.ReLU(inplace=True))
        self.add_module('conv', nn.Conv2d(num_input_features,
            num_output_features, kernel_size=1, stride=1, bias=False))
        self.add_module('pool', nn.AvgPool2d(kernel_size=2, stride=2))


class _DenseBlock(nn.Module):

    def __init__(self, num_layers, num_input_features, bn_size, growth_rate,
        drop_rate, efficient=False):
        super(_DenseBlock, self).__init__()
        for i in range(num_layers):
            layer = _DenseLayer(num_input_features + i * growth_rate,
                growth_rate=growth_rate, bn_size=bn_size, drop_rate=
                drop_rate, efficient=efficient)
            self.add_module('denselayer%d' % (i + 1), layer)

    def forward(self, init_features):
        features = [init_features]
        for name, layer in self.named_children():
            new_features = layer(*features)
            features.append(new_features)
        return torch.cat(features, 1)


class DenseNet_(nn.Module):
    """Densenet-BC model class, based on
    `"Densely Connected Convolutional Networks" <https://arxiv.org/pdf/1608.06993.pdf>`
    Args:
        growth_rate (int) - how many filters to add each layer (`k` in paper)
        block_config (list of 3 or 4 ints) - how many layers in each pooling block
        num_init_features (int) - the number of filters to learn in the first convolution layer
        compression (float) - a value between 0 and 1
        bn_size (int) - multiplicative factor for number of bottle neck layers
            (i.e. bn_size * k features in the bottleneck layer)
        drop_rate (float) - dropout rate after each dense layer
        num_classes (int) - number of classification classes
        small_inputs (bool) - set to True if images are 32x32. Otherwise assumes images are larger.
        efficient (bool) - set to True to use checkpointing. Much more memory efficient, but slower.
    """

    def __init__(self, growth_rate=12, block_config=(16, 16, 16),
        num_init_features=24, compression=0.5, bn_size=4, drop_rate=0,
        num_classes=10, small_inputs=True, efficient=False):
        super(DenseNet_, self).__init__()
        assert 0 < compression <= 1, 'compression of densenet should be between 0 and 1'
        if small_inputs:
            self.features = nn.Sequential(OrderedDict([('conv0', nn.Conv2d(
                3, num_init_features, kernel_size=3, stride=1, padding=1,
                bias=False))]))
        else:
            self.features = nn.Sequential(OrderedDict([('conv0', nn.Conv2d(
                3, num_init_features, kernel_size=7, stride=2, padding=3,
                bias=False))]))
            self.features.add_module('norm0', nn.BatchNorm2d(num_init_features)
                )
            self.features.add_module('relu0', nn.ReLU(inplace=True))
            self.features.add_module('pool0', nn.MaxPool2d(kernel_size=3,
                stride=2, padding=1, ceil_mode=False))
        num_features = num_init_features
        for i, num_layers in enumerate(block_config):
            block = _DenseBlock(num_layers=num_layers, num_input_features=
                num_features, bn_size=bn_size, growth_rate=growth_rate,
                drop_rate=drop_rate, efficient=efficient)
            self.features.add_module('denseblock%d' % (i + 1), block)
            num_features = num_features + num_layers * growth_rate
            if i != len(block_config) - 1:
                trans = _Transition(num_input_features=num_features,
                    num_output_features=int(num_features * compression))
                self.features.add_module('transition%d' % (i + 1), trans)
                num_features = int(num_features * compression)
        self.features.add_module('norm_final', nn.BatchNorm2d(num_features))
        self.classifier = nn.Linear(num_features, num_classes)
        for name, param in self.named_parameters():
            if 'conv' in name and 'weight' in name:
                n = param.size(0) * param.size(2) * param.size(3)
                param.data.normal_().mul_(math.sqrt(2.0 / n))
            elif 'norm' in name and 'weight' in name:
                param.data.fill_(1)
            elif 'norm' in name and 'bias' in name:
                param.data.fill_(0)
            elif 'classifier' in name and 'bias' in name:
                param.data.fill_(0)

    def forward(self, x):
        features = self.features(x)
        out = F.relu(features, inplace=True)
        out = F.adaptive_avg_pool2d(out, (1, 1))
        out = torch.flatten(out, 1)
        out = self.classifier(out)
        return out


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def densenet201(**kwargs) ->DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 48, 32),
        num_init_features=64, **kwargs)


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class _DenseLayer(nn.Module):

    def __init__(self, num_input_features, growth_rate, bn_size, drop_rate,
        efficient=False):
        super(_DenseLayer, self).__init__()
        self.add_module('norm1', nn.BatchNorm2d(num_input_features)),
        self.add_module('relu1', nn.ReLU(inplace=True)),
        self.add_module('conv1', nn.Conv2d(num_input_features, bn_size *
            growth_rate, kernel_size=1, stride=1, bias=False)),
        self.add_module('norm2', nn.BatchNorm2d(bn_size * growth_rate)),
        self.add_module('relu2', nn.ReLU(inplace=True)),
        self.add_module('conv2', nn.Conv2d(bn_size * growth_rate,
            growth_rate, kernel_size=3, stride=1, padding=1, bias=False)),
        self.drop_rate = drop_rate
        self.efficient = efficient

    def forward(self, *prev_features):
        bn_function = _bn_function_factory(self.norm1, self.relu1, self.conv1)
        if self.efficient and any(prev_feature.requires_grad for
            prev_feature in prev_features):
            bottleneck_output = cp.checkpoint(bn_function, *prev_features)
        else:
            bottleneck_output = bn_function(*prev_features)
        new_features = self.conv2(self.relu2(self.norm2(bottleneck_output)))
        if self.drop_rate > 0:
            new_features = F.dropout(new_features, p=self.drop_rate,
                training=self.training)
        return new_features


class _Transition(nn.Sequential):

    def __init__(self, num_input_features, num_output_features):
        super(_Transition, self).__init__()
        self.add_module('norm', nn.BatchNorm2d(num_input_features))
        self.add_module('relu', nn.ReLU(inplace=True))
        self.add_module('conv', nn.Conv2d(num_input_features,
            num_output_features, kernel_size=1, stride=1, bias=False))
        self.add_module('pool', nn.AvgPool2d(kernel_size=2, stride=2))


class _DenseBlock(nn.Module):

    def __init__(self, num_layers, num_input_features, bn_size, growth_rate,
        drop_rate, efficient=False):
        super(_DenseBlock, self).__init__()
        for i in range(num_layers):
            layer = _DenseLayer(num_input_features + i * growth_rate,
                growth_rate=growth_rate, bn_size=bn_size, drop_rate=
                drop_rate, efficient=efficient)
            self.add_module('denselayer%d' % (i + 1), layer)

    def forward(self, init_features):
        features = [init_features]
        for name, layer in self.named_children():
            new_features = layer(*features)
            features.append(new_features)
        return torch.cat(features, 1)


class DenseNet_(nn.Module):
    """Densenet-BC model class, based on
    `"Densely Connected Convolutional Networks" <https://arxiv.org/pdf/1608.06993.pdf>`
    Args:
        growth_rate (int) - how many filters to add each layer (`k` in paper)
        block_config (list of 3 or 4 ints) - how many layers in each pooling block
        num_init_features (int) - the number of filters to learn in the first convolution layer
        compression (float) - a value between 0 and 1
        bn_size (int) - multiplicative factor for number of bottle neck layers
            (i.e. bn_size * k features in the bottleneck layer)
        drop_rate (float) - dropout rate after each dense layer
        num_classes (int) - number of classification classes
        small_inputs (bool) - set to True if images are 32x32. Otherwise assumes images are larger.
        efficient (bool) - set to True to use checkpointing. Much more memory efficient, but slower.
    """

    def __init__(self, growth_rate=12, block_config=(16, 16, 16),
        num_init_features=24, compression=0.5, bn_size=4, drop_rate=0,
        num_classes=10, small_inputs=True, efficient=False):
        super(DenseNet_, self).__init__()
        assert 0 < compression <= 1, 'compression of densenet should be between 0 and 1'
        if small_inputs:
            self.features = nn.Sequential(OrderedDict([('conv0', nn.Conv2d(
                3, num_init_features, kernel_size=3, stride=1, padding=1,
                bias=False))]))
        else:
            self.features = nn.Sequential(OrderedDict([('conv0', nn.Conv2d(
                3, num_init_features, kernel_size=7, stride=2, padding=3,
                bias=False))]))
            self.features.add_module('norm0', nn.BatchNorm2d(num_init_features)
                )
            self.features.add_module('relu0', nn.ReLU(inplace=True))
            self.features.add_module('pool0', nn.MaxPool2d(kernel_size=3,
                stride=2, padding=1, ceil_mode=False))
        num_features = num_init_features
        for i, num_layers in enumerate(block_config):
            block = _DenseBlock(num_layers=num_layers, num_input_features=
                num_features, bn_size=bn_size, growth_rate=growth_rate,
                drop_rate=drop_rate, efficient=efficient)
            self.features.add_module('denseblock%d' % (i + 1), block)
            num_features = num_features + num_layers * growth_rate
            if i != len(block_config) - 1:
                trans = _Transition(num_input_features=num_features,
                    num_output_features=int(num_features * compression))
                self.features.add_module('transition%d' % (i + 1), trans)
                num_features = int(num_features * compression)
        self.features.add_module('norm_final', nn.BatchNorm2d(num_features))
        self.classifier = nn.Linear(num_features, num_classes)
        for name, param in self.named_parameters():
            if 'conv' in name and 'weight' in name:
                n = param.size(0) * param.size(2) * param.size(3)
                param.data.normal_().mul_(math.sqrt(2.0 / n))
            elif 'norm' in name and 'weight' in name:
                param.data.fill_(1)
            elif 'norm' in name and 'bias' in name:
                param.data.fill_(0)
            elif 'classifier' in name and 'bias' in name:
                param.data.fill_(0)

    def forward(self, x):
        features = self.features(x)
        out = F.relu(features, inplace=True)
        out = F.adaptive_avg_pool2d(out, (1, 1))
        out = torch.flatten(out, 1)
        out = self.classifier(out)
        return out


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def densenet201(**kwargs) ->DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 48, 32),
        num_init_features=64, **kwargs)


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def DenseNet(model_name: str, **kwargs) ->DenseNet_:
    if model_name not in VALID_MODELS:
        raise ValueError(f'Invalid model name: {model_name}')
    return VALID_MODELS[model_name](**kwargs)

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def _bn_function_factory(norm, relu, conv):

    def bn_function(*inputs):
        concated_features = torch.cat(inputs, 1)
        bottleneck_output = conv(relu(norm(concated_features)))
        return bottleneck_output
    return bn_function


class _DenseLayer(nn.Module):

    def __init__(self, num_input_features, growth_rate, bn_size, drop_rate,
        efficient=False):
        super(_DenseLayer, self).__init__()
        self.add_module('norm1', nn.BatchNorm2d(num_input_features)),
        self.add_module('relu1', nn.ReLU(inplace=True)),
        self.add_module('conv1', nn.Conv2d(num_input_features, bn_size *
            growth_rate, kernel_size=1, stride=1, bias=False)),
        self.add_module('norm2', nn.BatchNorm2d(bn_size * growth_rate)),
        self.add_module('relu2', nn.ReLU(inplace=True)),
        self.add_module('conv2', nn.Conv2d(bn_size * growth_rate,
            growth_rate, kernel_size=3, stride=1, padding=1, bias=False)),
        self.drop_rate = drop_rate
        self.efficient = efficient

    def forward(self, *prev_features):
        bn_function = _bn_function_factory(self.norm1, self.relu1, self.conv1)
        if self.efficient and any(prev_feature.requires_grad for
            prev_feature in prev_features):
            bottleneck_output = cp.checkpoint(bn_function, *prev_features)
        else:
            bottleneck_output = bn_function(*prev_features)
        new_features = self.conv2(self.relu2(self.norm2(bottleneck_output)))
        if self.drop_rate > 0:
            new_features = F.dropout(new_features, p=self.drop_rate,
                training=self.training)
        return new_features


class _Transition(nn.Sequential):

    def __init__(self, num_input_features, num_output_features):
        super(_Transition, self).__init__()
        self.add_module('norm', nn.BatchNorm2d(num_input_features))
        self.add_module('relu', nn.ReLU(inplace=True))
        self.add_module('conv', nn.Conv2d(num_input_features,
            num_output_features, kernel_size=1, stride=1, bias=False))
        self.add_module('pool', nn.AvgPool2d(kernel_size=2, stride=2))


class _DenseBlock(nn.Module):

    def __init__(self, num_layers, num_input_features, bn_size, growth_rate,
        drop_rate, efficient=False):
        super(_DenseBlock, self).__init__()
        for i in range(num_layers):
            layer = _DenseLayer(num_input_features + i * growth_rate,
                growth_rate=growth_rate, bn_size=bn_size, drop_rate=
                drop_rate, efficient=efficient)
            self.add_module('denselayer%d' % (i + 1), layer)

    def forward(self, init_features):
        features = [init_features]
        for name, layer in self.named_children():
            new_features = layer(*features)
            features.append(new_features)
        return torch.cat(features, 1)


class DenseNet_(nn.Module):
    """Densenet-BC model class, based on
    `"Densely Connected Convolutional Networks" <https://arxiv.org/pdf/1608.06993.pdf>`
    Args:
        growth_rate (int) - how many filters to add each layer (`k` in paper)
        block_config (list of 3 or 4 ints) - how many layers in each pooling block
        num_init_features (int) - the number of filters to learn in the first convolution layer
        compression (float) - a value between 0 and 1
        bn_size (int) - multiplicative factor for number of bottle neck layers
            (i.e. bn_size * k features in the bottleneck layer)
        drop_rate (float) - dropout rate after each dense layer
        num_classes (int) - number of classification classes
        small_inputs (bool) - set to True if images are 32x32. Otherwise assumes images are larger.
        efficient (bool) - set to True to use checkpointing. Much more memory efficient, but slower.
    """

    def __init__(self, growth_rate=12, block_config=(16, 16, 16),
        num_init_features=24, compression=0.5, bn_size=4, drop_rate=0,
        num_classes=10, small_inputs=True, efficient=False):
        super(DenseNet_, self).__init__()
        assert 0 < compression <= 1, 'compression of densenet should be between 0 and 1'
        if small_inputs:
            self.features = nn.Sequential(OrderedDict([('conv0', nn.Conv2d(
                3, num_init_features, kernel_size=3, stride=1, padding=1,
                bias=False))]))
        else:
            self.features = nn.Sequential(OrderedDict([('conv0', nn.Conv2d(
                3, num_init_features, kernel_size=7, stride=2, padding=3,
                bias=False))]))
            self.features.add_module('norm0', nn.BatchNorm2d(num_init_features)
                )
            self.features.add_module('relu0', nn.ReLU(inplace=True))
            self.features.add_module('pool0', nn.MaxPool2d(kernel_size=3,
                stride=2, padding=1, ceil_mode=False))
        num_features = num_init_features
        for i, num_layers in enumerate(block_config):
            block = _DenseBlock(num_layers=num_layers, num_input_features=
                num_features, bn_size=bn_size, growth_rate=growth_rate,
                drop_rate=drop_rate, efficient=efficient)
            self.features.add_module('denseblock%d' % (i + 1), block)
            num_features = num_features + num_layers * growth_rate
            if i != len(block_config) - 1:
                trans = _Transition(num_input_features=num_features,
                    num_output_features=int(num_features * compression))
                self.features.add_module('transition%d' % (i + 1), trans)
                num_features = int(num_features * compression)
        self.features.add_module('norm_final', nn.BatchNorm2d(num_features))
        self.classifier = nn.Linear(num_features, num_classes)
        for name, param in self.named_parameters():
            if 'conv' in name and 'weight' in name:
                n = param.size(0) * param.size(2) * param.size(3)
                param.data.normal_().mul_(math.sqrt(2.0 / n))
            elif 'norm' in name and 'weight' in name:
                param.data.fill_(1)
            elif 'norm' in name and 'bias' in name:
                param.data.fill_(0)
            elif 'classifier' in name and 'bias' in name:
                param.data.fill_(0)

    def forward(self, x):
        features = self.features(x)
        out = F.relu(features, inplace=True)
        out = F.adaptive_avg_pool2d(out, (1, 1))
        out = torch.flatten(out, 1)
        out = self.classifier(out)
        return out


def _densenet(growth_rate: int, block_config, num_init_features: int, **kwargs
    ) ->DenseNet_:
    if 'num_init_features' in kwargs:
        num_init_features = kwargs['num_init_features']
    model = DenseNet_(growth_rate, block_config, num_init_features, **kwargs)
    return model


def densenet121(**kwargs) ->DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 24, 16),
        num_init_features=64, **kwargs)


<mask token>


def densenet169(**kwargs) ->DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 32, 32),
        num_init_features=64, **kwargs)


def densenet201(**kwargs) ->DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 48, 32),
        num_init_features=64, **kwargs)


<mask token>


def DenseNet(model_name: str, **kwargs) ->DenseNet_:
    if model_name not in VALID_MODELS:
        raise ValueError(f'Invalid model name: {model_name}')
    return VALID_MODELS[model_name](**kwargs)

import math
import torch
import torch.nn as nn
import torch.nn.functional as F
import torch.utils.checkpoint as cp
from collections import OrderedDict


def _bn_function_factory(norm, relu, conv):

    def bn_function(*inputs):
        concated_features = torch.cat(inputs, 1)
        bottleneck_output = conv(relu(norm(concated_features)))
        return bottleneck_output
    return bn_function


class _DenseLayer(nn.Module):

    def __init__(self, num_input_features, growth_rate, bn_size, drop_rate,
        efficient=False):
        super(_DenseLayer, self).__init__()
        self.add_module('norm1', nn.BatchNorm2d(num_input_features)),
        self.add_module('relu1', nn.ReLU(inplace=True)),
        self.add_module('conv1', nn.Conv2d(num_input_features, bn_size *
            growth_rate, kernel_size=1, stride=1, bias=False)),
        self.add_module('norm2', nn.BatchNorm2d(bn_size * growth_rate)),
        self.add_module('relu2', nn.ReLU(inplace=True)),
        self.add_module('conv2', nn.Conv2d(bn_size * growth_rate,
            growth_rate, kernel_size=3, stride=1, padding=1, bias=False)),
        self.drop_rate = drop_rate
        self.efficient = efficient

    def forward(self, *prev_features):
        bn_function = _bn_function_factory(self.norm1, self.relu1, self.conv1)
        if self.efficient and any(prev_feature.requires_grad for
            prev_feature in prev_features):
            bottleneck_output = cp.checkpoint(bn_function, *prev_features)
        else:
            bottleneck_output = bn_function(*prev_features)
        new_features = self.conv2(self.relu2(self.norm2(bottleneck_output)))
        if self.drop_rate > 0:
            new_features = F.dropout(new_features, p=self.drop_rate,
                training=self.training)
        return new_features


class _Transition(nn.Sequential):

    def __init__(self, num_input_features, num_output_features):
        super(_Transition, self).__init__()
        self.add_module('norm', nn.BatchNorm2d(num_input_features))
        self.add_module('relu', nn.ReLU(inplace=True))
        self.add_module('conv', nn.Conv2d(num_input_features,
            num_output_features, kernel_size=1, stride=1, bias=False))
        self.add_module('pool', nn.AvgPool2d(kernel_size=2, stride=2))


class _DenseBlock(nn.Module):

    def __init__(self, num_layers, num_input_features, bn_size, growth_rate,
        drop_rate, efficient=False):
        super(_DenseBlock, self).__init__()
        for i in range(num_layers):
            layer = _DenseLayer(num_input_features + i * growth_rate,
                growth_rate=growth_rate, bn_size=bn_size, drop_rate=
                drop_rate, efficient=efficient)
            self.add_module('denselayer%d' % (i + 1), layer)

    def forward(self, init_features):
        features = [init_features]
        for name, layer in self.named_children():
            new_features = layer(*features)
            features.append(new_features)
        return torch.cat(features, 1)


class DenseNet_(nn.Module):
    """Densenet-BC model class, based on
    `"Densely Connected Convolutional Networks" <https://arxiv.org/pdf/1608.06993.pdf>`
    Args:
        growth_rate (int) - how many filters to add each layer (`k` in paper)
        block_config (list of 3 or 4 ints) - how many layers in each pooling block
        num_init_features (int) - the number of filters to learn in the first convolution layer
        compression (float) - a value between 0 and 1
        bn_size (int) - multiplicative factor for number of bottle neck layers
            (i.e. bn_size * k features in the bottleneck layer)
        drop_rate (float) - dropout rate after each dense layer
        num_classes (int) - number of classification classes
        small_inputs (bool) - set to True if images are 32x32. Otherwise assumes images are larger.
        efficient (bool) - set to True to use checkpointing. Much more memory efficient, but slower.
    """

    def __init__(self, growth_rate=12, block_config=(16, 16, 16),
        num_init_features=24, compression=0.5, bn_size=4, drop_rate=0,
        num_classes=10, small_inputs=True, efficient=False):
        super(DenseNet_, self).__init__()
        assert 0 < compression <= 1, 'compression of densenet should be between 0 and 1'
        if small_inputs:
            self.features = nn.Sequential(OrderedDict([('conv0', nn.Conv2d(
                3, num_init_features, kernel_size=3, stride=1, padding=1,
                bias=False))]))
        else:
            self.features = nn.Sequential(OrderedDict([('conv0', nn.Conv2d(
                3, num_init_features, kernel_size=7, stride=2, padding=3,
                bias=False))]))
            self.features.add_module('norm0', nn.BatchNorm2d(num_init_features)
                )
            self.features.add_module('relu0', nn.ReLU(inplace=True))
            self.features.add_module('pool0', nn.MaxPool2d(kernel_size=3,
                stride=2, padding=1, ceil_mode=False))
        num_features = num_init_features
        for i, num_layers in enumerate(block_config):
            block = _DenseBlock(num_layers=num_layers, num_input_features=
                num_features, bn_size=bn_size, growth_rate=growth_rate,
                drop_rate=drop_rate, efficient=efficient)
            self.features.add_module('denseblock%d' % (i + 1), block)
            num_features = num_features + num_layers * growth_rate
            if i != len(block_config) - 1:
                trans = _Transition(num_input_features=num_features,
                    num_output_features=int(num_features * compression))
                self.features.add_module('transition%d' % (i + 1), trans)
                num_features = int(num_features * compression)
        self.features.add_module('norm_final', nn.BatchNorm2d(num_features))
        self.classifier = nn.Linear(num_features, num_classes)
        for name, param in self.named_parameters():
            if 'conv' in name and 'weight' in name:
                n = param.size(0) * param.size(2) * param.size(3)
                param.data.normal_().mul_(math.sqrt(2.0 / n))
            elif 'norm' in name and 'weight' in name:
                param.data.fill_(1)
            elif 'norm' in name and 'bias' in name:
                param.data.fill_(0)
            elif 'classifier' in name and 'bias' in name:
                param.data.fill_(0)

    def forward(self, x):
        features = self.features(x)
        out = F.relu(features, inplace=True)
        out = F.adaptive_avg_pool2d(out, (1, 1))
        out = torch.flatten(out, 1)
        out = self.classifier(out)
        return out


def _densenet(growth_rate: int, block_config, num_init_features: int, **kwargs
    ) ->DenseNet_:
    if 'num_init_features' in kwargs:
        num_init_features = kwargs['num_init_features']
    model = DenseNet_(growth_rate, block_config, num_init_features, **kwargs)
    return model


def densenet121(**kwargs) ->DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 24, 16),
        num_init_features=64, **kwargs)


def densenet161(**kwargs) ->DenseNet_:
    return _densenet(growth_rate=48, block_config=(6, 12, 36, 24),
        num_init_features=96, **kwargs)


def densenet169(**kwargs) ->DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 32, 32),
        num_init_features=64, **kwargs)


def densenet201(**kwargs) ->DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 48, 32),
        num_init_features=64, **kwargs)


VALID_MODELS = {'densenet121': densenet121, 'densenet161': densenet161,
    'densenet169': densenet169, 'densenet201': densenet201}


def DenseNet(model_name: str, **kwargs) ->DenseNet_:
    if model_name not in VALID_MODELS:
        raise ValueError(f'Invalid model name: {model_name}')
    return VALID_MODELS[model_name](**kwargs)

# "Densely Connected Convolutional Networks" <https://arxiv.org/pdf/1608.06993.pdf>
# Reference: https://github.com/pytorch/vision/blob/main/torchvision/models/densenet.py

import math
import torch
import torch.nn as nn
import torch.nn.functional as F
import torch.utils.checkpoint as cp
from collections import OrderedDict


def _bn_function_factory(norm, relu, conv):
    def bn_function(*inputs):
        concated_features = torch.cat(inputs, 1)
        bottleneck_output = conv(relu(norm(concated_features)))
        return bottleneck_output

    return bn_function


class _DenseLayer(nn.Module):
    def __init__(self, num_input_features, growth_rate, bn_size, drop_rate, efficient=False):
        super(_DenseLayer, self).__init__()
        self.add_module("norm1", nn.BatchNorm2d(num_input_features)),
        self.add_module("relu1", nn.ReLU(inplace=True)),
        self.add_module(
            "conv1",
            nn.Conv2d(
                num_input_features,
                bn_size * growth_rate,
                kernel_size=1,
                stride=1,
                bias=False,
            ),
        ),
        self.add_module("norm2", nn.BatchNorm2d(bn_size * growth_rate)),
        self.add_module("relu2", nn.ReLU(inplace=True)),
        self.add_module(
            "conv2",
            nn.Conv2d(
                bn_size * growth_rate,
                growth_rate,
                kernel_size=3,
                stride=1,
                padding=1,
                bias=False,
            ),
        ),
        self.drop_rate = drop_rate
        self.efficient = efficient

    def forward(self, *prev_features):
        bn_function = _bn_function_factory(self.norm1, self.relu1, self.conv1)
        if self.efficient and any(prev_feature.requires_grad for prev_feature in prev_features):
            bottleneck_output = cp.checkpoint(bn_function, *prev_features)
        else:
            bottleneck_output = bn_function(*prev_features)
        new_features = self.conv2(self.relu2(self.norm2(bottleneck_output)))
        if self.drop_rate > 0:
            new_features = F.dropout(new_features, p=self.drop_rate, training=self.training)
        return new_features


class _Transition(nn.Sequential):
    def __init__(self, num_input_features, num_output_features):
        super(_Transition, self).__init__()
        self.add_module("norm", nn.BatchNorm2d(num_input_features))
        self.add_module("relu", nn.ReLU(inplace=True))
        self.add_module(
            "conv",
            nn.Conv2d(
                num_input_features,
                num_output_features,
                kernel_size=1,
                stride=1,
                bias=False,
            ),
        )
        self.add_module("pool", nn.AvgPool2d(kernel_size=2, stride=2))


class _DenseBlock(nn.Module):
    def __init__(
        self,
        num_layers,
        num_input_features,
        bn_size,
        growth_rate,
        drop_rate,
        efficient=False,
    ):
        super(_DenseBlock, self).__init__()
        for i in range(num_layers):
            layer = _DenseLayer(
                num_input_features + i * growth_rate,
                growth_rate=growth_rate,
                bn_size=bn_size,
                drop_rate=drop_rate,
                efficient=efficient,
            )
            self.add_module("denselayer%d" % (i + 1), layer)

    def forward(self, init_features):
        features = [init_features]
        for name, layer in self.named_children():
            new_features = layer(*features)
            features.append(new_features)
        return torch.cat(features, 1)


class DenseNet_(nn.Module):
    r"""Densenet-BC model class, based on
    `"Densely Connected Convolutional Networks" <https://arxiv.org/pdf/1608.06993.pdf>`
    Args:
        growth_rate (int) - how many filters to add each layer (`k` in paper)
        block_config (list of 3 or 4 ints) - how many layers in each pooling block
        num_init_features (int) - the number of filters to learn in the first convolution layer
        compression (float) - a value between 0 and 1
        bn_size (int) - multiplicative factor for number of bottle neck layers
            (i.e. bn_size * k features in the bottleneck layer)
        drop_rate (float) - dropout rate after each dense layer
        num_classes (int) - number of classification classes
        small_inputs (bool) - set to True if images are 32x32. Otherwise assumes images are larger.
        efficient (bool) - set to True to use checkpointing. Much more memory efficient, but slower.
    """

    def __init__(
        self,
        growth_rate=12,
        block_config=(16, 16, 16),
        num_init_features=24,
        compression=0.5,
        bn_size=4,
        drop_rate=0,
        num_classes=10,
        small_inputs=True,
        efficient=False,
    ):

        super(DenseNet_, self).__init__()
        assert 0 < compression <= 1, "compression of densenet should be between 0 and 1"

        # First convolution
        if small_inputs:
            self.features = nn.Sequential(
                OrderedDict(
                    [
                        (
                            "conv0",
                            nn.Conv2d(
                                3,
                                num_init_features,
                                kernel_size=3,
                                stride=1,
                                padding=1,
                                bias=False,
                            ),
                        ),
                    ]
                )
            )
        else:
            self.features = nn.Sequential(
                OrderedDict(
                    [
                        (
                            "conv0",
                            nn.Conv2d(
                                3,
                                num_init_features,
                                kernel_size=7,
                                stride=2,
                                padding=3,
                                bias=False,
                            ),
                        ),
                    ]
                )
            )
            self.features.add_module("norm0", nn.BatchNorm2d(num_init_features))
            self.features.add_module("relu0", nn.ReLU(inplace=True))
            self.features.add_module(
                "pool0",
                nn.MaxPool2d(kernel_size=3, stride=2, padding=1, ceil_mode=False),
            )

        # Each denseblock
        num_features = num_init_features
        for i, num_layers in enumerate(block_config):
            block = _DenseBlock(
                num_layers=num_layers,
                num_input_features=num_features,
                bn_size=bn_size,
                growth_rate=growth_rate,
                drop_rate=drop_rate,
                efficient=efficient,
            )
            self.features.add_module("denseblock%d" % (i + 1), block)
            num_features = num_features + num_layers * growth_rate
            if i != len(block_config) - 1:
                trans = _Transition(
                    num_input_features=num_features,
                    num_output_features=int(num_features * compression),
                )
                self.features.add_module("transition%d" % (i + 1), trans)
                num_features = int(num_features * compression)

        # Final batch norm
        self.features.add_module("norm_final", nn.BatchNorm2d(num_features))

        # Linear layer
        self.classifier = nn.Linear(num_features, num_classes)

        # Initialization
        for name, param in self.named_parameters():
            if "conv" in name and "weight" in name:
                n = param.size(0) * param.size(2) * param.size(3)
                param.data.normal_().mul_(math.sqrt(2.0 / n))
            elif "norm" in name and "weight" in name:
                param.data.fill_(1)
            elif "norm" in name and "bias" in name:
                param.data.fill_(0)
            elif "classifier" in name and "bias" in name:
                param.data.fill_(0)

    def forward(self, x):
        features = self.features(x)
        out = F.relu(features, inplace=True)
        out = F.adaptive_avg_pool2d(out, (1, 1))
        out = torch.flatten(out, 1)
        out = self.classifier(out)
        return out


def _densenet(
    growth_rate: int,
    block_config,
    num_init_features: int,
    **kwargs,
) -> DenseNet_:
    if "num_init_features" in kwargs:
        num_init_features = kwargs["num_init_features"]

    model = DenseNet_(growth_rate, block_config, num_init_features, **kwargs)
    return model


def densenet121(**kwargs) -> DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 24, 16), num_init_features=64, **kwargs)


def densenet161(**kwargs) -> DenseNet_:
    return _densenet(growth_rate=48, block_config=(6, 12, 36, 24), num_init_features=96, **kwargs)


def densenet169(**kwargs) -> DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 32, 32), num_init_features=64, **kwargs)


def densenet201(**kwargs) -> DenseNet_:
    return _densenet(growth_rate=32, block_config=(6, 12, 48, 32), num_init_features=64, **kwargs)


VALID_MODELS = {
    "densenet121": densenet121,
    "densenet161": densenet161,
    "densenet169": densenet169,
    "densenet201": densenet201,
}


def DenseNet(model_name: str, **kwargs) -> DenseNet_:
    if model_name not in VALID_MODELS:
        raise ValueError(f"Invalid model name: {model_name}")
    return VALID_MODELS[model_name](**kwargs)
