# this file is adapted from https://github.com/victorca25/iNNfer

import math
from collections import OrderedDict

import torch
import torch.nn as nn
import torch.nn.functional as F

####################
# RRDBNet Generator
####################


class RRDBNet(nn.Module):
    def __init__(
        self,
        in_nc,
        out_nc,
        nf,
        nb,
        nr=3,
        gc=32,
        upscale=4,
        norm_type=None,
        act_type="leakyrelu",
        mode="CNA",
        upsample_mode="upconv",
        convtype="Conv2D",
        finalact=None,
        gaussian_noise=False,
        plus=False,
    ):
        super(RRDBNet, self).__init__()
        n_upscale = int(math.log(upscale, 2))
        if upscale == 3:
            n_upscale = 1

        self.resrgan_scale = 0
        if in_nc % 16 == 0:
            self.resrgan_scale = 1
        elif in_nc != 4 and in_nc % 4 == 0:
            self.resrgan_scale = 2

        fea_conv = conv_block(
            in_nc, nf, kernel_size=3, norm_type=None, act_type=None, convtype=convtype
        )
        rb_blocks = [
            RRDB(
                nf,
                nr,
                kernel_size=3,
                gc=32,
                stride=1,
                bias=1,
                pad_type="zero",
                norm_type=norm_type,
                act_type=act_type,
                mode="CNA",
                convtype=convtype,
                gaussian_noise=gaussian_noise,
                plus=plus,
            )
            for _ in range(nb)
        ]
        LR_conv = conv_block(
            nf,
            nf,
            kernel_size=3,
            norm_type=norm_type,
            act_type=None,
            mode=mode,
            convtype=convtype,
        )

        if upsample_mode == "upconv":
            upsample_block = upconv_block
        elif upsample_mode == "pixelshuffle":
            upsample_block = pixelshuffle_block
        else:
            raise NotImplementedError(f"upsample mode [{upsample_mode}] is not found")
        if upscale == 3:
            upsampler = upsample_block(nf, nf, 3, act_type=act_type, convtype=convtype)
        else:
            upsampler = [
                upsample_block(nf, nf, act_type=act_type, convtype=convtype)
                for _ in range(n_upscale)
            ]
        HR_conv0 = conv_block(
            nf, nf, kernel_size=3, norm_type=None, act_type=act_type, convtype=convtype
        )
        HR_conv1 = conv_block(
            nf, out_nc, kernel_size=3, norm_type=None, act_type=None, convtype=convtype
        )

        outact = act(finalact) if finalact else None

        self.model = sequential(
            fea_conv,
            ShortcutBlock(sequential(*rb_blocks, LR_conv)),
            *upsampler,
            HR_conv0,
            HR_conv1,
            outact,
        )

    def forward(self, x, outm=None):
        if self.resrgan_scale == 1:
            feat = pixel_unshuffle(x, scale=4)
        elif self.resrgan_scale == 2:
            feat = pixel_unshuffle(x, scale=2)
        else:
            feat = x

        return self.model(feat)


class RRDB(nn.Module):
    """
    Residual in Residual Dense Block
    (ESRGAN: Enhanced Super-Resolution Generative Adversarial Networks)
    """

    def __init__(
        self,
        nf,
        nr=3,
        kernel_size=3,
        gc=32,
        stride=1,
        bias=1,
        pad_type="zero",
        norm_type=None,
        act_type="leakyrelu",
        mode="CNA",
        convtype="Conv2D",
        spectral_norm=False,
        gaussian_noise=False,
        plus=False,
    ):
        super(RRDB, self).__init__()
        # This is for backwards compatibility with existing models
        if nr == 3:
            self.RDB1 = ResidualDenseBlock_5C(
                nf,
                kernel_size,
                gc,
                stride,
                bias,
                pad_type,
                norm_type,
                act_type,
                mode,
                convtype,
                spectral_norm=spectral_norm,
                gaussian_noise=gaussian_noise,
                plus=plus,
            )
            self.RDB2 = ResidualDenseBlock_5C(
                nf,
                kernel_size,
                gc,
                stride,
                bias,
                pad_type,
                norm_type,
                act_type,
                mode,
                convtype,
                spectral_norm=spectral_norm,
                gaussian_noise=gaussian_noise,
                plus=plus,
            )
            self.RDB3 = ResidualDenseBlock_5C(
                nf,
                kernel_size,
                gc,
                stride,
                bias,
                pad_type,
                norm_type,
                act_type,
                mode,
                convtype,
                spectral_norm=spectral_norm,
                gaussian_noise=gaussian_noise,
                plus=plus,
            )
        else:
            RDB_list = [
                ResidualDenseBlock_5C(
                    nf,
                    kernel_size,
                    gc,
                    stride,
                    bias,
                    pad_type,
                    norm_type,
                    act_type,
                    mode,
                    convtype,
                    spectral_norm=spectral_norm,
                    gaussian_noise=gaussian_noise,
                    plus=plus,
                )
                for _ in range(nr)
            ]
            self.RDBs = nn.Sequential(*RDB_list)

    def forward(self, x):
        if hasattr(self, "RDB1"):
            out = self.RDB1(x)
            out = self.RDB2(out)
            out = self.RDB3(out)
        else:
            out = self.RDBs(x)
        return out * 0.2 + x


class ResidualDenseBlock_5C(nn.Module):
    """
    Residual Dense Block
    The core module of paper: (Residual Dense Network for Image Super-Resolution, CVPR 18)
    Modified options that can be used:
        - "Partial Convolution based Padding" arXiv:1811.11718
        - "Spectral normalization" arXiv:1802.05957
        - "ICASSP 2020 - ESRGAN+ : Further Improving ESRGAN" N. C.
            {Rakotonirina} and A. {Rasoanaivo}
    """

    def __init__(
        self,
        nf=64,
        kernel_size=3,
        gc=32,
        stride=1,
        bias=1,
        pad_type="zero",
        norm_type=None,
        act_type="leakyrelu",
        mode="CNA",
        convtype="Conv2D",
        spectral_norm=False,
        gaussian_noise=False,
        plus=False,
    ):
        super(ResidualDenseBlock_5C, self).__init__()

        self.noise = GaussianNoise() if gaussian_noise else None
        self.conv1x1 = conv1x1(nf, gc) if plus else None

        self.conv1 = conv_block(
            nf,
            gc,
            kernel_size,
            stride,
            bias=bias,
            pad_type=pad_type,
            norm_type=norm_type,
            act_type=act_type,
            mode=mode,
            convtype=convtype,
            spectral_norm=spectral_norm,
        )
        self.conv2 = conv_block(
            nf + gc,
            gc,
            kernel_size,
            stride,
            bias=bias,
            pad_type=pad_type,
            norm_type=norm_type,
            act_type=act_type,
            mode=mode,
            convtype=convtype,
            spectral_norm=spectral_norm,
        )
        self.conv3 = conv_block(
            nf + 2 * gc,
            gc,
            kernel_size,
            stride,
            bias=bias,
            pad_type=pad_type,
            norm_type=norm_type,
            act_type=act_type,
            mode=mode,
            convtype=convtype,
            spectral_norm=spectral_norm,
        )
        self.conv4 = conv_block(
            nf + 3 * gc,
            gc,
            kernel_size,
            stride,
            bias=bias,
            pad_type=pad_type,
            norm_type=norm_type,
            act_type=act_type,
            mode=mode,
            convtype=convtype,
            spectral_norm=spectral_norm,
        )
        if mode == "CNA":
            last_act = None
        else:
            last_act = act_type
        self.conv5 = conv_block(
            nf + 4 * gc,
            nf,
            3,
            stride,
            bias=bias,
            pad_type=pad_type,
            norm_type=norm_type,
            act_type=last_act,
            mode=mode,
            convtype=convtype,
            spectral_norm=spectral_norm,
        )

    def forward(self, x):
        x1 = self.conv1(x)
        x2 = self.conv2(torch.cat((x, x1), 1))
        if self.conv1x1:
            x2 = x2 + self.conv1x1(x)
        x3 = self.conv3(torch.cat((x, x1, x2), 1))
        x4 = self.conv4(torch.cat((x, x1, x2, x3), 1))
        if self.conv1x1:
            x4 = x4 + x2
        x5 = self.conv5(torch.cat((x, x1, x2, x3, x4), 1))
        if self.noise:
            return self.noise(x5.mul(0.2) + x)
        else:
            return x5 * 0.2 + x


####################
# ESRGANplus
####################


class GaussianNoise(nn.Module):
    def __init__(self, sigma=0.1, is_relative_detach=False):
        super().__init__()
        self.sigma = sigma
        self.is_relative_detach = is_relative_detach
        self.noise = torch.tensor(0, dtype=torch.float)

    def forward(self, x):
        if self.training and self.sigma != 0:
            self.noise = self.noise.to(x.device)
            scale = (
                self.sigma * x.detach() if self.is_relative_detach else self.sigma * x
            )
            sampled_noise = self.noise.repeat(*x.size()).normal_() * scale
            x = x + sampled_noise
        return x


def conv1x1(in_planes, out_planes, stride=1):
    return nn.Conv2d(in_planes, out_planes, kernel_size=1, stride=stride, bias=False)


####################
# SRVGGNetCompact
####################


class SRVGGNetCompact(nn.Module):
    """A compact VGG-style network structure for super-resolution.
    This class is copied from https://github.com/xinntao/Real-ESRGAN
    """

    def __init__(
        self,
        num_in_ch=3,
        num_out_ch=3,
        num_feat=64,
        num_conv=16,
        upscale=4,
        act_type="prelu",
    ):
        super(SRVGGNetCompact, self).__init__()
        self.num_in_ch = num_in_ch
        self.num_out_ch = num_out_ch
        self.num_feat = num_feat
        self.num_conv = num_conv
        self.upscale = upscale
        self.act_type = act_type

        self.body = nn.ModuleList()
        # the first conv
        self.body.append(nn.Conv2d(num_in_ch, num_feat, 3, 1, 1))
        # the first activation
        if act_type == "relu":
            activation = nn.ReLU(inplace=True)
        elif act_type == "prelu":
            activation = nn.PReLU(num_parameters=num_feat)
        elif act_type == "leakyrelu":
            activation = nn.LeakyReLU(negative_slope=0.1, inplace=True)
        self.body.append(activation)

        # the body structure
        for _ in range(num_conv):
            self.body.append(nn.Conv2d(num_feat, num_feat, 3, 1, 1))
            # activation
            if act_type == "relu":
                activation = nn.ReLU(inplace=True)
            elif act_type == "prelu":
                activation = nn.PReLU(num_parameters=num_feat)
            elif act_type == "leakyrelu":
                activation = nn.LeakyReLU(negative_slope=0.1, inplace=True)
            self.body.append(activation)

        # the last conv
        self.body.append(nn.Conv2d(num_feat, num_out_ch * upscale * upscale, 3, 1, 1))
        # upsample
        self.upsampler = nn.PixelShuffle(upscale)

    def forward(self, x):
        out = x
        for i in range(0, len(self.body)):
            out = self.body[i](out)

        out = self.upsampler(out)
        # add the nearest upsampled image, so that the network learns the residual
        base = F.interpolate(x, scale_factor=self.upscale, mode="nearest")
        out += base
        return out


####################
# Upsampler
####################


class Upsample(nn.Module):
    r"""Upsamples a given multi-channel 1D (temporal), 2D (spatial) or 3D (volumetric) data.
    The input data is assumed to be of the form
    `minibatch x channels x [optional depth] x [optional height] x width`.
    """

    def __init__(
        self, size=None, scale_factor=None, mode="nearest", align_corners=None
    ):
        super(Upsample, self).__init__()
        if isinstance(scale_factor, tuple):
            self.scale_factor = tuple(float(factor) for factor in scale_factor)
        else:
            self.scale_factor = float(scale_factor) if scale_factor else None
        self.mode = mode
        self.size = size
        self.align_corners = align_corners

    def forward(self, x):
        return nn.functional.interpolate(
            x,
            size=self.size,
            scale_factor=self.scale_factor,
            mode=self.mode,
            align_corners=self.align_corners,
        )

    def extra_repr(self):
        if self.scale_factor is not None:
            info = f"scale_factor={self.scale_factor}"
        else:
            info = f"size={self.size}"
        info += f", mode={self.mode}"
        return info


def pixel_unshuffle(x, scale):
    """Pixel unshuffle.
    Args:
        x (Tensor): Input feature with shape (b, c, hh, hw).
        scale (int): Downsample ratio.
    Returns:
        Tensor: the pixel unshuffled feature.
    """
    b, c, hh, hw = x.size()
    out_channel = c * (scale**2)
    assert hh % scale == 0 and hw % scale == 0
    h = hh // scale
    w = hw // scale
    x_view = x.view(b, c, h, scale, w, scale)
    return x_view.permute(0, 1, 3, 5, 2, 4).reshape(b, out_channel, h, w)


def pixelshuffle_block(
    in_nc,
    out_nc,
    upscale_factor=2,
    kernel_size=3,
    stride=1,
    bias=True,
    pad_type="zero",
    norm_type=None,
    act_type="relu",
    convtype="Conv2D",
):
    """
    Pixel shuffle layer
    (Real-Time Single Image and Video Super-Resolution Using an Efficient Sub-Pixel Convolutional
    Neural Network, CVPR17)
    """
    conv = conv_block(
        in_nc,
        out_nc * (upscale_factor**2),
        kernel_size,
        stride,
        bias=bias,
        pad_type=pad_type,
        norm_type=None,
        act_type=None,
        convtype=convtype,
    )
    pixel_shuffle = nn.PixelShuffle(upscale_factor)

    n = norm(norm_type, out_nc) if norm_type else None
    a = act(act_type) if act_type else None
    return sequential(conv, pixel_shuffle, n, a)


def upconv_block(
    in_nc,
    out_nc,
    upscale_factor=2,
    kernel_size=3,
    stride=1,
    bias=True,
    pad_type="zero",
    norm_type=None,
    act_type="relu",
    mode="nearest",
    convtype="Conv2D",
):
    """Upconv layer"""
    upscale_factor = (
        (1, upscale_factor, upscale_factor) if convtype == "Conv3D" else upscale_factor
    )
    upsample = Upsample(scale_factor=upscale_factor, mode=mode)
    conv = conv_block(
        in_nc,
        out_nc,
        kernel_size,
        stride,
        bias=bias,
        pad_type=pad_type,
        norm_type=norm_type,
        act_type=act_type,
        convtype=convtype,
    )
    return sequential(upsample, conv)


####################
# Basic blocks
####################


def make_layer(basic_block, num_basic_block, **kwarg):
    """Make layers by stacking the same blocks.
    Args:
        basic_block (nn.module): nn.module class for basic block. (block)
        num_basic_block (int): number of blocks. (n_layers)
    Returns:
        nn.Sequential: Stacked blocks in nn.Sequential.
    """
    layers = []
    for _ in range(num_basic_block):
        layers.append(basic_block(**kwarg))
    return nn.Sequential(*layers)


def act(act_type, inplace=True, neg_slope=0.2, n_prelu=1, beta=1.0):
    """activation helper"""
    act_type = act_type.lower()
    if act_type == "relu":
        layer = nn.ReLU(inplace)
    elif act_type in ("leakyrelu", "lrelu"):
        layer = nn.LeakyReLU(neg_slope, inplace)
    elif act_type == "prelu":
        layer = nn.PReLU(num_parameters=n_prelu, init=neg_slope)
    elif act_type == "tanh":  # [-1, 1] range output
        layer = nn.Tanh()
    elif act_type == "sigmoid":  # [0, 1] range output
        layer = nn.Sigmoid()
    else:
        raise NotImplementedError(f"activation layer [{act_type}] is not found")
    return layer


class Identity(nn.Module):
    def __init__(self, *kwargs):
        super(Identity, self).__init__()

    def forward(self, x, *kwargs):
        return x


def norm(norm_type, nc):
    """Return a normalization layer"""
    norm_type = norm_type.lower()
    if norm_type == "batch":
        layer = nn.BatchNorm2d(nc, affine=True)
    elif norm_type == "instance":
        layer = nn.InstanceNorm2d(nc, affine=False)
    elif norm_type == "none":

        def norm_layer(x):
            return Identity()

    else:
        raise NotImplementedError(f"normalization layer [{norm_type}] is not found")
    return layer


def pad(pad_type, padding):
    """padding layer helper"""
    pad_type = pad_type.lower()
    if padding == 0:
        return None
    if pad_type == "reflect":
        layer = nn.ReflectionPad2d(padding)
    elif pad_type == "replicate":
        layer = nn.ReplicationPad2d(padding)
    elif pad_type == "zero":
        layer = nn.ZeroPad2d(padding)
    else:
        raise NotImplementedError(f"padding layer [{pad_type}] is not implemented")
    return layer


def get_valid_padding(kernel_size, dilation):
    kernel_size = kernel_size + (kernel_size - 1) * (dilation - 1)
    padding = (kernel_size - 1) // 2
    return padding


class ShortcutBlock(nn.Module):
    """Elementwise sum the output of a submodule to its input"""

    def __init__(self, submodule):
        super(ShortcutBlock, self).__init__()
        self.sub = submodule

    def forward(self, x):
        output = x + self.sub(x)
        return output

    def __repr__(self):
        return "Identity + \n|" + self.sub.__repr__().replace("\n", "\n|")


def sequential(*args):
    """Flatten Sequential. It unwraps nn.Sequential."""
    if len(args) == 1:
        if isinstance(args[0], OrderedDict):
            raise NotImplementedError("sequential does not support OrderedDict input.")
        return args[0]  # No sequential is needed.
    modules = []
    for module in args:
        if isinstance(module, nn.Sequential):
            for submodule in module.children():
                modules.append(submodule)
        elif isinstance(module, nn.Module):
            modules.append(module)
    return nn.Sequential(*modules)


def conv_block(
    in_nc,
    out_nc,
    kernel_size,
    stride=1,
    dilation=1,
    groups=1,
    bias=True,
    pad_type="zero",
    norm_type=None,
    act_type="relu",
    mode="CNA",
    convtype="Conv2D",
    spectral_norm=False,
):
    """Conv layer with padding, normalization, activation"""
    assert mode in ["CNA", "NAC", "CNAC"], f"Wrong conv mode [{mode}]"
    padding = get_valid_padding(kernel_size, dilation)
    p = pad(pad_type, padding) if pad_type and pad_type != "zero" else None
    padding = padding if pad_type == "zero" else 0

    if convtype == "PartialConv2D":
        from torchvision.ops import (
            PartialConv2d,
        )  # this is definitely not going to work, but PartialConv2d doesn't work anyway and this shuts up static analyzer

        c = PartialConv2d(
            in_nc,
            out_nc,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            bias=bias,
            groups=groups,
        )
    elif convtype == "DeformConv2D":
        from torchvision.ops import DeformConv2d  # not tested

        c = DeformConv2d(
            in_nc,
            out_nc,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            bias=bias,
            groups=groups,
        )
    elif convtype == "Conv3D":
        c = nn.Conv3d(
            in_nc,
            out_nc,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            bias=bias,
            groups=groups,
        )
    else:
        c = nn.Conv2d(
            in_nc,
            out_nc,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            bias=bias,
            groups=groups,
        )

    if spectral_norm:
        c = nn.utils.spectral_norm(c)

    a = act(act_type) if act_type else None
    if "CNA" in mode:
        n = norm(norm_type, out_nc) if norm_type else None
        return sequential(p, c, n, a)
    elif mode == "NAC":
        if norm_type is None and act_type is not None:
            a = act(act_type, inplace=False)
        n = norm(norm_type, in_nc) if norm_type else None
        return sequential(n, a, p, c)