# Copyright (c) Facebook, Inc. and its affiliates.
# All rights reserved.
#
# This source code is licensed under the license found in the
# LICENSE file in the root directory of this source tree.

# Optional list of dependencies required by the package
dependencies = ['torch', 'torchvision']

from torch.hub import load_state_dict_from_url
from torchvision.models.resnet import ResNet, Bottleneck


model_urls = {
    'resnext101_32x8d': 'https://download.pytorch.org/models/ig_resnext101_32x8-c38310e5.pth',
    'resnext101_32x16d': 'https://download.pytorch.org/models/ig_resnext101_32x16-c6f796b0.pth',
    'resnext101_32x32d': 'https://download.pytorch.org/models/ig_resnext101_32x32-e4b90b00.pth',
    'resnext101_32x48d': 'https://download.pytorch.org/models/ig_resnext101_32x48-3e41cc8a.pth',
}


def _resnext(arch, block, layers, pretrained, progress, **kwargs):
    model = ResNet(block, layers, **kwargs)
    state_dict = load_state_dict_from_url(model_urls[arch], progress=progress)
    model.load_state_dict(state_dict)
    return model


def resnext101_32x8d_wsl(progress=True, **kwargs):
    """Constructs a ResNeXt-101 32x8 model pre-trained on weakly-supervised data
    and finetuned on ImageNet from Figure 5 in
    `"Exploring the Limits of Weakly Supervised Pretraining" <https://arxiv.org/abs/1805.00932>`_

    Args:
        progress (bool): If True, displays a progress bar of the download to stderr.
    """
    kwargs['groups'] = 32
    kwargs['width_per_group'] = 8
    return _resnext('resnext101_32x8d', Bottleneck, [3, 4, 23, 3], True, progress, **kwargs)


def resnext101_32x16d_wsl(progress=True, **kwargs):
    """Constructs a ResNeXt-101 32x16 model pre-trained on weakly-supervised data
    and finetuned on ImageNet from Figure 5 in
    `"Exploring the Limits of Weakly Supervised Pretraining" <https://arxiv.org/abs/1805.00932>`_

    Args:
        progress (bool): If True, displays a progress bar of the download to stderr.
    """
    kwargs['groups'] = 32
    kwargs['width_per_group'] = 16
    return _resnext('resnext101_32x16d', Bottleneck, [3, 4, 23, 3], True, progress, **kwargs)


def resnext101_32x32d_wsl(progress=True, **kwargs):
    """Constructs a ResNeXt-101 32x32 model pre-trained on weakly-supervised data
    and finetuned on ImageNet from Figure 5 in
    `"Exploring the Limits of Weakly Supervised Pretraining" <https://arxiv.org/abs/1805.00932>`_

    Args:
        progress (bool): If True, displays a progress bar of the download to stderr.
    """
    kwargs['groups'] = 32
    kwargs['width_per_group'] = 32
    return _resnext('resnext101_32x32d', Bottleneck, [3, 4, 23, 3], True, progress, **kwargs)


def resnext101_32x48d_wsl(progress=True, **kwargs):
    """Constructs a ResNeXt-101 32x48 model pre-trained on weakly-supervised data
    and finetuned on ImageNet from Figure 5 in
    `"Exploring the Limits of Weakly Supervised Pretraining" <https://arxiv.org/abs/1805.00932>`_

    Args:
        progress (bool): If True, displays a progress bar of the download to stderr.
    """
    kwargs['groups'] = 32
    kwargs['width_per_group'] = 48
    return _resnext('resnext101_32x48d', Bottleneck, [3, 4, 23, 3], True, progress, **kwargs)