# Portions of source code adapted from the following sources:
#   https://github.com/mseitzer/pytorch-fid/blob/master/src/pytorch_fid/inception.py
#   Distributed under Apache License 2.0: https://github.com/mseitzer/pytorch-fid/blob/master/LICENSE

import sys
from contextlib import redirect_stdout

import torch
import torch.nn as nn
import torch.nn.functional as F
from torch.hub import load_state_dict_from_url

from torch_fidelity.feature_extractor_base import FeatureExtractorBase
from torch_fidelity.helpers import vassert, text_to_dtype
from torch_fidelity.interpolate_compat_tensorflow import interpolate_bilinear_2d_like_tensorflow1x

# InceptionV3 weights converted from the official TensorFlow weights using utils/util_convert_inception_weights.py
#   Original weights distributed under Apache License 2.0: https://github.com/tensorflow/models/blob/master/LICENSE
URL_INCEPTION_V3 = \
    'https://github.com/toshas/torch-fidelity/releases/download/v0.2.0/weights-inception-2015-12-05-6726825d.pth'


class FeatureExtractorInceptionV3(FeatureExtractorBase):
    INPUT_IMAGE_SIZE = 299

    def __init__(
            self,
            name,
            features_list,
            feature_extractor_weights_path=None,
            feature_extractor_internal_dtype=None,
            **kwargs,
    ):
        """
        InceptionV3 feature extractor for 2D RGB 24bit images.

        Args:

            name (str): Unique name of the feature extractor, must be the same as used in
                :func:`register_feature_extractor`.

            features_list (list): A list of the requested feature names, which will be produced for each input. This
                feature extractor provides the following features:

                - '64'
                - '192'
                - '768'
                - '2048'
                - 'logits_unbiased'
                - 'logits'

            feature_extractor_weights_path (str): Path to the pretrained InceptionV3 model weights in PyTorch format.
                Refer to `util_convert_inception_weights` for making your own. Downloads from internet if `None`.

            feature_extractor_internal_dtype (str): dtype to use inside the feature extractor. Specifying it may improve
                numerical precision in some cases. Supported values are 'float32' (default), and 'float64'.
        """
        super(FeatureExtractorInceptionV3, self).__init__(name, features_list)
        vassert(
            feature_extractor_internal_dtype in ('float32', 'float64', None),
            'Only 32 and 64 bit floats are supported for internal dtype of this feature extractor'
        )
        self.feature_extractor_internal_dtype = text_to_dtype(feature_extractor_internal_dtype, 'float32')

        self.Conv2d_1a_3x3 = BasicConv2d(3, 32, kernel_size=3, stride=2)
        self.Conv2d_2a_3x3 = BasicConv2d(32, 32, kernel_size=3)
        self.Conv2d_2b_3x3 = BasicConv2d(32, 64, kernel_size=3, padding=1)
        self.MaxPool_1 = nn.MaxPool2d(kernel_size=3, stride=2)

        self.Conv2d_3b_1x1 = BasicConv2d(64, 80, kernel_size=1)
        self.Conv2d_4a_3x3 = BasicConv2d(80, 192, kernel_size=3)
        self.MaxPool_2 = nn.MaxPool2d(kernel_size=3, stride=2)

        self.Mixed_5b = InceptionA(192, pool_features=32)
        self.Mixed_5c = InceptionA(256, pool_features=64)
        self.Mixed_5d = InceptionA(288, pool_features=64)
        self.Mixed_6a = InceptionB(288)
        self.Mixed_6b = InceptionC(768, channels_7x7=128)
        self.Mixed_6c = InceptionC(768, channels_7x7=160)
        self.Mixed_6d = InceptionC(768, channels_7x7=160)
        self.Mixed_6e = InceptionC(768, channels_7x7=192)

        self.Mixed_7a = InceptionD(768)
        self.Mixed_7b = InceptionE_1(1280)
        self.Mixed_7c = InceptionE_2(2048)
        self.AvgPool = nn.AdaptiveAvgPool2d(output_size=(1, 1))

        self.fc = nn.Linear(2048, 1008)

        if feature_extractor_weights_path is None:
            with redirect_stdout(sys.stderr):
                state_dict = load_state_dict_from_url(URL_INCEPTION_V3, progress=True)
        else:
            state_dict = torch.load(feature_extractor_weights_path)
        self.load_state_dict(state_dict)

        self.to(self.feature_extractor_internal_dtype)
        self.requires_grad_(False)
        self.eval()

    def forward(self, x):
        vassert(torch.is_tensor(x) and x.dtype == torch.uint8, 'Expecting image as torch.Tensor with dtype=torch.uint8')
        vassert(x.dim() == 4 and x.shape[1] == 3, f'Input is not Bx3xHxW: {x.shape}')
        features = {}
        remaining_features = self.features_list.copy()

        x = x.to(self.feature_extractor_internal_dtype)
        # N x 3 x ? x ?

        x = interpolate_bilinear_2d_like_tensorflow1x(
            x,
            size=(self.INPUT_IMAGE_SIZE, self.INPUT_IMAGE_SIZE),
            align_corners=False,
        )
        # N x 3 x 299 x 299

        # x = (x - 128) * torch.tensor(0.0078125, dtype=torch.float32, device=x.device)  # really happening in graph
        x = (x - 128) / 128  # but this gives bit-exact output _of this step_ too
        # N x 3 x 299 x 299

        x = self.Conv2d_1a_3x3(x)
        # N x 32 x 149 x 149
        x = self.Conv2d_2a_3x3(x)
        # N x 32 x 147 x 147
        x = self.Conv2d_2b_3x3(x)
        # N x 64 x 147 x 147
        x = self.MaxPool_1(x)
        # N x 64 x 73 x 73

        if '64' in remaining_features:
            features['64'] = F.adaptive_avg_pool2d(x, output_size=(1, 1)).squeeze(-1).squeeze(-1).to(torch.float32)
            remaining_features.remove('64')
            if len(remaining_features) == 0:
                return tuple(features[a] for a in self.features_list)

        x = self.Conv2d_3b_1x1(x)
        # N x 80 x 73 x 73
        x = self.Conv2d_4a_3x3(x)
        # N x 192 x 71 x 71
        x = self.MaxPool_2(x)
        # N x 192 x 35 x 35

        if '192' in remaining_features:
            features['192'] = F.adaptive_avg_pool2d(x, output_size=(1, 1)).squeeze(-1).squeeze(-1).to(torch.float32)
            remaining_features.remove('192')
            if len(remaining_features) == 0:
                return tuple(features[a] for a in self.features_list)

        x = self.Mixed_5b(x)
        # N x 256 x 35 x 35
        x = self.Mixed_5c(x)
        # N x 288 x 35 x 35
        x = self.Mixed_5d(x)
        # N x 288 x 35 x 35
        x = self.Mixed_6a(x)
        # N x 768 x 17 x 17
        x = self.Mixed_6b(x)
        # N x 768 x 17 x 17
        x = self.Mixed_6c(x)
        # N x 768 x 17 x 17
        x = self.Mixed_6d(x)
        # N x 768 x 17 x 17
        x = self.Mixed_6e(x)
        # N x 768 x 17 x 17

        if '768' in remaining_features:
            features['768'] = F.adaptive_avg_pool2d(x, output_size=(1, 1)).squeeze(-1).squeeze(-1).to(torch.float32)
            remaining_features.remove('768')
            if len(remaining_features) == 0:
                return tuple(features[a] for a in self.features_list)

        x = self.Mixed_7a(x)
        # N x 1280 x 8 x 8
        x = self.Mixed_7b(x)
        # N x 2048 x 8 x 8
        x = self.Mixed_7c(x)
        # N x 2048 x 8 x 8
        x = self.AvgPool(x)
        # N x 2048 x 1 x 1

        x = torch.flatten(x, 1)
        # N x 2048

        if '2048' in remaining_features:
            features['2048'] = x.to(torch.float32)
            remaining_features.remove('2048')
            if len(remaining_features) == 0:
                return tuple(features[a] for a in self.features_list)

        if 'logits_unbiased' in remaining_features:
            x = x.mm(self.fc.weight.T)
            # N x 1008 (num_classes)
            features['logits_unbiased'] = x.to(torch.float32)
            remaining_features.remove('logits_unbiased')
            if len(remaining_features) == 0:
                return tuple(features[a] for a in self.features_list)

            x = x + self.fc.bias.unsqueeze(0)
        else:
            x = self.fc(x)
            # N x 1008 (num_classes)

        features['logits'] = x.to(torch.float32)
        return tuple(features[a] for a in self.features_list)

    @staticmethod
    def get_provided_features_list():
        return '64', '192', '768', '2048', 'logits_unbiased', 'logits'

    @staticmethod
    def get_default_feature_layer_for_metric(metric):
        return {
            'isc': 'logits_unbiased',
            'fid': '2048',
            'kid': '2048',
            'prc': '2048',
        }[metric]

    @staticmethod
    def can_be_compiled():
        return True

    @staticmethod
    def get_dummy_input_for_compile():
        return (torch.rand([1, 3, 4, 4]) * 255).to(torch.uint8)


class BasicConv2d(nn.Module):
    """Original BasicConv2d block"""
    def __init__(self, in_channels, out_channels, **kwargs):
        super(BasicConv2d, self).__init__()
        self.conv = nn.Conv2d(in_channels, out_channels, bias=False, **kwargs)
        self.bn = nn.BatchNorm2d(out_channels, eps=0.001)

    def forward(self, x):
        x = self.conv(x)
        x = self.bn(x)
        return F.relu(x, inplace=True)


class InceptionA(nn.Module):
    """Block from torchvision patched to be compatible with TensorFlow implementation"""
    def __init__(self, in_channels, pool_features):
        super(InceptionA, self).__init__()
        self.branch1x1 = BasicConv2d(in_channels, 64, kernel_size=1)

        self.branch5x5_1 = BasicConv2d(in_channels, 48, kernel_size=1)
        self.branch5x5_2 = BasicConv2d(48, 64, kernel_size=5, padding=2)

        self.branch3x3dbl_1 = BasicConv2d(in_channels, 64, kernel_size=1)
        self.branch3x3dbl_2 = BasicConv2d(64, 96, kernel_size=3, padding=1)
        self.branch3x3dbl_3 = BasicConv2d(96, 96, kernel_size=3, padding=1)

        self.branch_pool = BasicConv2d(in_channels, pool_features, kernel_size=1)

    def forward(self, x):
        branch1x1 = self.branch1x1(x)

        branch5x5 = self.branch5x5_1(x)
        branch5x5 = self.branch5x5_2(branch5x5)

        branch3x3dbl = self.branch3x3dbl_1(x)
        branch3x3dbl = self.branch3x3dbl_2(branch3x3dbl)
        branch3x3dbl = self.branch3x3dbl_3(branch3x3dbl)

        # Patch: Tensorflow's average pool does not use the padded zero's in its average calculation
        branch_pool = F.avg_pool2d(x, kernel_size=3, stride=1, padding=1, count_include_pad=False)
        branch_pool = self.branch_pool(branch_pool)

        outputs = [branch1x1, branch5x5, branch3x3dbl, branch_pool]
        return torch.cat(outputs, 1)


class InceptionB(nn.Module):
    """Original block"""
    def __init__(self, in_channels):
        super(InceptionB, self).__init__()
        self.branch3x3 = BasicConv2d(in_channels, 384, kernel_size=3, stride=2)

        self.branch3x3dbl_1 = BasicConv2d(in_channels, 64, kernel_size=1)
        self.branch3x3dbl_2 = BasicConv2d(64, 96, kernel_size=3, padding=1)
        self.branch3x3dbl_3 = BasicConv2d(96, 96, kernel_size=3, stride=2)

    def forward(self, x):
        branch3x3 = self.branch3x3(x)

        branch3x3dbl = self.branch3x3dbl_1(x)
        branch3x3dbl = self.branch3x3dbl_2(branch3x3dbl)
        branch3x3dbl = self.branch3x3dbl_3(branch3x3dbl)

        branch_pool = F.max_pool2d(x, kernel_size=3, stride=2)

        outputs = [branch3x3, branch3x3dbl, branch_pool]
        return torch.cat(outputs, 1)


class InceptionC(nn.Module):
    """Block from torchvision patched to be compatible with TensorFlow implementation"""
    def __init__(self, in_channels, channels_7x7):
        super(InceptionC, self).__init__()
        self.branch1x1 = BasicConv2d(in_channels, 192, kernel_size=1)

        c7 = channels_7x7
        self.branch7x7_1 = BasicConv2d(in_channels, c7, kernel_size=1)
        self.branch7x7_2 = BasicConv2d(c7, c7, kernel_size=(1, 7), padding=(0, 3))
        self.branch7x7_3 = BasicConv2d(c7, 192, kernel_size=(7, 1), padding=(3, 0))

        self.branch7x7dbl_1 = BasicConv2d(in_channels, c7, kernel_size=1)
        self.branch7x7dbl_2 = BasicConv2d(c7, c7, kernel_size=(7, 1), padding=(3, 0))
        self.branch7x7dbl_3 = BasicConv2d(c7, c7, kernel_size=(1, 7), padding=(0, 3))
        self.branch7x7dbl_4 = BasicConv2d(c7, c7, kernel_size=(7, 1), padding=(3, 0))
        self.branch7x7dbl_5 = BasicConv2d(c7, 192, kernel_size=(1, 7), padding=(0, 3))

        self.branch_pool = BasicConv2d(in_channels, 192, kernel_size=1)

    def forward(self, x):
        branch1x1 = self.branch1x1(x)

        branch7x7 = self.branch7x7_1(x)
        branch7x7 = self.branch7x7_2(branch7x7)
        branch7x7 = self.branch7x7_3(branch7x7)

        branch7x7dbl = self.branch7x7dbl_1(x)
        branch7x7dbl = self.branch7x7dbl_2(branch7x7dbl)
        branch7x7dbl = self.branch7x7dbl_3(branch7x7dbl)
        branch7x7dbl = self.branch7x7dbl_4(branch7x7dbl)
        branch7x7dbl = self.branch7x7dbl_5(branch7x7dbl)

        # Patch: Tensorflow's average pool does not use the padded zero's in its average calculation
        branch_pool = F.avg_pool2d(x, kernel_size=3, stride=1, padding=1, count_include_pad=False)
        branch_pool = self.branch_pool(branch_pool)

        outputs = [branch1x1, branch7x7, branch7x7dbl, branch_pool]
        return torch.cat(outputs, 1)


class InceptionD(nn.Module):
    """Original block"""
    def __init__(self, in_channels):
        super(InceptionD, self).__init__()
        self.branch3x3_1 = BasicConv2d(in_channels, 192, kernel_size=1)
        self.branch3x3_2 = BasicConv2d(192, 320, kernel_size=3, stride=2)

        self.branch7x7x3_1 = BasicConv2d(in_channels, 192, kernel_size=1)
        self.branch7x7x3_2 = BasicConv2d(192, 192, kernel_size=(1, 7), padding=(0, 3))
        self.branch7x7x3_3 = BasicConv2d(192, 192, kernel_size=(7, 1), padding=(3, 0))
        self.branch7x7x3_4 = BasicConv2d(192, 192, kernel_size=3, stride=2)

    def forward(self, x):
        branch3x3 = self.branch3x3_1(x)
        branch3x3 = self.branch3x3_2(branch3x3)

        branch7x7x3 = self.branch7x7x3_1(x)
        branch7x7x3 = self.branch7x7x3_2(branch7x7x3)
        branch7x7x3 = self.branch7x7x3_3(branch7x7x3)
        branch7x7x3 = self.branch7x7x3_4(branch7x7x3)

        branch_pool = F.max_pool2d(x, kernel_size=3, stride=2)
        outputs = [branch3x3, branch7x7x3, branch_pool]
        return torch.cat(outputs, 1)


class InceptionE_1(nn.Module):
    """First InceptionE block from torchvision patched to be compatible with TensorFlow implementation"""
    def __init__(self, in_channels):
        super(InceptionE_1, self).__init__()
        self.branch1x1 = BasicConv2d(in_channels, 320, kernel_size=1)

        self.branch3x3_1 = BasicConv2d(in_channels, 384, kernel_size=1)
        self.branch3x3_2a = BasicConv2d(384, 384, kernel_size=(1, 3), padding=(0, 1))
        self.branch3x3_2b = BasicConv2d(384, 384, kernel_size=(3, 1), padding=(1, 0))

        self.branch3x3dbl_1 = BasicConv2d(in_channels, 448, kernel_size=1)
        self.branch3x3dbl_2 = BasicConv2d(448, 384, kernel_size=3, padding=1)
        self.branch3x3dbl_3a = BasicConv2d(384, 384, kernel_size=(1, 3), padding=(0, 1))
        self.branch3x3dbl_3b = BasicConv2d(384, 384, kernel_size=(3, 1), padding=(1, 0))

        self.branch_pool = BasicConv2d(in_channels, 192, kernel_size=1)

    def forward(self, x):
        branch1x1 = self.branch1x1(x)

        branch3x3 = self.branch3x3_1(x)
        branch3x3 = [
            self.branch3x3_2a(branch3x3),
            self.branch3x3_2b(branch3x3),
        ]
        branch3x3 = torch.cat(branch3x3, 1)

        branch3x3dbl = self.branch3x3dbl_1(x)
        branch3x3dbl = self.branch3x3dbl_2(branch3x3dbl)
        branch3x3dbl = [
            self.branch3x3dbl_3a(branch3x3dbl),
            self.branch3x3dbl_3b(branch3x3dbl),
        ]
        branch3x3dbl = torch.cat(branch3x3dbl, 1)

        # Patch: Tensorflow's average pool does not use the padded zero's in its average calculation
        branch_pool = F.avg_pool2d(x, kernel_size=3, stride=1, padding=1, count_include_pad=False)
        branch_pool = self.branch_pool(branch_pool)

        outputs = [branch1x1, branch3x3, branch3x3dbl, branch_pool]
        return torch.cat(outputs, 1)


class InceptionE_2(nn.Module):
    """Second InceptionE block from torchvision patched to be compatible with TensorFlow implementation"""
    def __init__(self, in_channels):
        super(InceptionE_2, self).__init__()
        self.branch1x1 = BasicConv2d(in_channels, 320, kernel_size=1)

        self.branch3x3_1 = BasicConv2d(in_channels, 384, kernel_size=1)
        self.branch3x3_2a = BasicConv2d(384, 384, kernel_size=(1, 3), padding=(0, 1))
        self.branch3x3_2b = BasicConv2d(384, 384, kernel_size=(3, 1), padding=(1, 0))

        self.branch3x3dbl_1 = BasicConv2d(in_channels, 448, kernel_size=1)
        self.branch3x3dbl_2 = BasicConv2d(448, 384, kernel_size=3, padding=1)
        self.branch3x3dbl_3a = BasicConv2d(384, 384, kernel_size=(1, 3), padding=(0, 1))
        self.branch3x3dbl_3b = BasicConv2d(384, 384, kernel_size=(3, 1), padding=(1, 0))

        self.branch_pool = BasicConv2d(in_channels, 192, kernel_size=1)

    def forward(self, x):
        branch1x1 = self.branch1x1(x)

        branch3x3 = self.branch3x3_1(x)
        branch3x3 = [
            self.branch3x3_2a(branch3x3),
            self.branch3x3_2b(branch3x3),
        ]
        branch3x3 = torch.cat(branch3x3, 1)

        branch3x3dbl = self.branch3x3dbl_1(x)
        branch3x3dbl = self.branch3x3dbl_2(branch3x3dbl)
        branch3x3dbl = [
            self.branch3x3dbl_3a(branch3x3dbl),
            self.branch3x3dbl_3b(branch3x3dbl),
        ]
        branch3x3dbl = torch.cat(branch3x3dbl, 1)

        # Patch: TensorFlow Inception model uses max pooling instead of average
        # pooling. This is likely an error in this specific Inception
        # implementation, as other Inception models use average pooling here
        # (which matches the description in the paper).
        branch_pool = F.max_pool2d(x, kernel_size=3, stride=1, padding=1)
        branch_pool = self.branch_pool(branch_pool)

        outputs = [branch1x1, branch3x3, branch3x3dbl, branch_pool]
        return torch.cat(outputs, 1)
