# Copyright (c) Facebook, Inc. and 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.
import torch
from torchvision.models.resnet import resnet50

import vision_transformer as vits

dependencies = ["torch", "torchvision"]


def dino_deits16(pretrained=True, **kwargs):
    """
    DeiT-Small/16x16 pre-trained with DINO.
    Achieves 74.5% top-1 accuracy on ImageNet with k-NN classification.
    """
    model = vits.__dict__["deit_small"](patch_size=16, num_classes=0, **kwargs)
    if pretrained:
        state_dict = torch.hub.load_state_dict_from_url(
            url="https://dl.fbaipublicfiles.com/dino/dino_deitsmall16_pretrain/dino_deitsmall16_pretrain.pth",
            map_location="cpu",
        )
        model.load_state_dict(state_dict, strict=True)
    return model


def dino_deits8(pretrained=True, **kwargs):
    """
    DeiT-Small/8x8 pre-trained with DINO.
    Achieves 78.3% top-1 accuracy on ImageNet with k-NN classification.
    """
    model = vits.__dict__["deit_small"](patch_size=8, num_classes=0, **kwargs)
    if pretrained:
        state_dict = torch.hub.load_state_dict_from_url(
            url="https://dl.fbaipublicfiles.com/dino/dino_deitsmall8_pretrain/dino_deitsmall8_pretrain.pth",
            map_location="cpu",
        )
        model.load_state_dict(state_dict, strict=True)
    return model


def dino_vitb16(pretrained=True, **kwargs):
    """
    ViT-Base/16x16 pre-trained with DINO.
    Achieves 76.1% top-1 accuracy on ImageNet with k-NN classification.
    """
    model = vits.__dict__["vit_base"](patch_size=16, num_classes=0, **kwargs)
    if pretrained:
        state_dict = torch.hub.load_state_dict_from_url(
            url="https://dl.fbaipublicfiles.com/dino/dino_vitbase16_pretrain/dino_vitbase16_pretrain.pth",
            map_location="cpu",
        )
        model.load_state_dict(state_dict, strict=True)
    return model


def dino_vitb8(pretrained=True, **kwargs):
    """
    ViT-Base/8x8 pre-trained with DINO.
    Achieves 77.4% top-1 accuracy on ImageNet with k-NN classification.
    """
    model = vits.__dict__["vit_base"](patch_size=8, num_classes=0, **kwargs)
    if pretrained:
        state_dict = torch.hub.load_state_dict_from_url(
            url="https://dl.fbaipublicfiles.com/dino/dino_vitbase8_pretrain/dino_vitbase8_pretrain.pth",
            map_location="cpu",
        )
        model.load_state_dict(state_dict, strict=True)
    return model


def dino_resnet50(pretrained=True, **kwargs):
    """
    ResNet-50 pre-trained with DINO.
    Achieves 75.3% top-1 accuracy on ImageNet linear evaluation benchmark (requires to train `fc`).
    Note that `fc.weight` and `fc.bias` are randomly initialized.
    """
    model = resnet50(pretrained=False, **kwargs)
    if pretrained:
        state_dict = torch.hub.load_state_dict_from_url(
            url="https://dl.fbaipublicfiles.com/dino/dino_resnet50_pretrain/dino_resnet50_pretrain.pth",
            map_location="cpu",
        )
        model.load_state_dict(state_dict, strict=False)
    return model
