import torch
import torch.nn as nn
from torch.nn import init
import functools
from torch.optim import lr_scheduler
from collections import OrderedDict


'''
Helper functions for model
Borrow tons of code from https://github.com/junyanz/pytorch-CycleGAN-and-pix2pix/blob/master/models/networks.py
'''

def get_norm_layer(norm_type='instance'):
    """Return a normalization layer
    Parameters:
        norm_type (str) -- the name of the normalization layer: batch | instance | none
    For BatchNorm, we use learnable affine parameters and track running statistics (mean/stddev).
    For InstanceNorm, we do not use learnable affine parameters. We do not track running statistics.
    """
    if norm_type == 'batch':
        norm_layer = functools.partial(nn.BatchNorm2d, affine=True, track_running_stats=True)
    elif norm_type == 'instance':   
        # change default flag, make sure instance norm behave as the same in both train and eval
        # https://github.com/junyanz/pytorch-CycleGAN-and-pix2pix/issues/395
        norm_layer = functools.partial(nn.InstanceNorm2d, affine=False, track_running_stats=False)
    elif norm_type == 'none':
        norm_layer = None
    else:
        raise NotImplementedError('normalization layer [%s] is not found' % norm_type)
    return norm_layer


def get_scheduler(optimizer, opt):
    if opt.lr_policy == 'lambda':
        def lambda_rule(epoch):
            lr_l = 1.0 - max(0, epoch + 1 + opt.epoch_count - opt.niter) / float(opt.niter_decay + 1)
            return lr_l
        scheduler = lr_scheduler.LambdaLR(optimizer, lr_lambda=lambda_rule)
    elif opt.lr_policy == 'step':
        scheduler = lr_scheduler.StepLR(optimizer, step_size=opt.lr_decay_iters, gamma=0.1)
    elif opt.lr_policy == 'plateau':
        scheduler = lr_scheduler.ReduceLROnPlateau(optimizer, mode='min', factor=0.2, threshold=0.01, patience=5)
    else:
        return NotImplementedError('learning rate policy [%s] is not implemented', opt.lr_policy)
    return scheduler


def init_weights(net, init_type='normal', gain=0.02):
    def init_func(m):
        classname = m.__class__.__name__
        if hasattr(m, 'weight') and (classname.find('Conv') != -1 or classname.find('Linear') != -1):
            if init_type == 'normal':
                init.normal_(m.weight.data, 0.0, gain)
            elif init_type == 'xavier':
                init.xavier_normal_(m.weight.data, gain=gain)
            elif init_type == 'kaiming':
                init.kaiming_normal_(m.weight.data, a=0, mode='fan_in')
            elif init_type == 'orthogonal':
                init.orthogonal_(m.weight.data, gain=gain)
            else:
                raise NotImplementedError('initialization method [%s] is not implemented' % init_type)
            if hasattr(m, 'bias') and m.bias is not None:
                init.constant_(m.bias.data, 0.0)
        elif classname.find('BatchNorm2d') != -1:
            init.normal_(m.weight.data, 1.0, gain)
            init.constant_(m.bias.data, 0.0)

    print('initialize network with %s' % init_type)
    net.apply(init_func)


def init_net(net, init_type='normal', init_gain=0.02, gpu_ids=[]):
    if len(gpu_ids) > 0:
        # print("gpu_ids,", gpu_ids)
        assert(torch.cuda.is_available())
        net.to(gpu_ids[0])
        net = torch.nn.DataParallel(net, gpu_ids)
    init_weights(net, init_type, gain=init_gain)
    return net


def define_G(input_nc, output_nc, ngf, which_model_netG, norm='batch', use_dropout=False, init_type='normal', init_gain=0.02, gpu_ids=[]):
    netG = None
    norm_layer = get_norm_layer(norm_type=norm)

    if which_model_netG == 'resnet_9blocks':
        netG = ResnetGenerator(input_nc, output_nc, ngf, norm_layer=norm_layer, use_dropout=use_dropout, n_blocks=9)
    elif which_model_netG == 'resnet_6blocks':
        netG = ResnetGenerator(input_nc, output_nc, ngf, norm_layer=norm_layer, use_dropout=use_dropout, n_blocks=6)
    elif which_model_netG == 'unet_128':
        netG = UnetGenerator(input_nc, output_nc, 7, ngf, norm_layer=norm_layer, use_dropout=use_dropout)
    elif which_model_netG == 'unet_256':
        netG = UnetGenerator(input_nc, output_nc, 8, ngf, norm_layer=norm_layer, use_dropout=use_dropout)
    else:
        raise NotImplementedError('Generator model name [%s] is not recognized' % which_model_netG)
    return init_net(netG, init_type, init_gain, gpu_ids)


def define_D(input_nc, ndf, which_model_netD,
             n_layers_D=3, norm='batch', use_sigmoid=False, init_type='normal', init_gain=0.02, gpu_ids=[]):
    netD = None
    norm_layer = get_norm_layer(norm_type=norm)

    if which_model_netD == 'basic':
        netD = NLayerDiscriminator(input_nc, ndf, n_layers=3, norm_layer=norm_layer, use_sigmoid=use_sigmoid)
    elif which_model_netD == 'n_layers':
        netD = NLayerDiscriminator(input_nc, ndf, n_layers_D, norm_layer=norm_layer, use_sigmoid=use_sigmoid)
    elif which_model_netD == 'pixel':
        netD = PixelDiscriminator(input_nc, ndf, norm_layer=norm_layer, use_sigmoid=use_sigmoid)
    else:
        raise NotImplementedError('Discriminator model name [%s] is not recognized' %
                                  which_model_netD)
    return init_net(netD, init_type, init_gain, gpu_ids)


##############################################################################
# Classes
##############################################################################


# Defines the GAN loss which uses either LSGAN or the regular GAN.
# When LSGAN is used, it is basically same as MSELoss,
# but it abstracts away the need to create the target label tensor
# that has the same size as the input
class GANLoss(nn.Module):
    def __init__(self, gan_type='wgan-gp', target_real_label=1.0, target_fake_label=0.0):
        super(GANLoss, self).__init__()
        self.register_buffer('real_label', torch.tensor(target_real_label))
        self.register_buffer('fake_label', torch.tensor(target_fake_label))
        self.gan_type = gan_type
        if self.gan_type == 'wgan-gp':
            self.loss = lambda x, y: -torch.mean(x) if y else torch.mean(x)
        elif self.gan_type == 'lsgan':
            self.loss = nn.MSELoss()
        elif self.gan_type == 'gan':
            self.loss = nn.BCELoss()
        else:
            raise NotImplementedError('GAN loss type [%s] is not found' % gan_type)

    def get_target_tensor(self, input, target_is_real):
        if target_is_real:
            target_tensor = self.real_label
        else:
            target_tensor = self.fake_label
        return target_tensor.expand_as(input)

    def __call__(self, input, target_is_real):
        if self.gan_type == 'wgan-gp':
            target_tensor = target_is_real
        else:
            target_tensor = self.get_target_tensor(input, target_is_real)
        return self.loss(input, target_tensor)


# Defines the generator that consists of Resnet blocks between a few
# downsampling/upsampling operations.
# Code and idea originally from Justin Johnson's architecture.
# https://github.com/jcjohnson/fast-neural-style/
class ResnetGenerator(nn.Module):
    def __init__(self, input_nc, output_nc, ngf=64, norm_layer=nn.BatchNorm2d, use_dropout=False, n_blocks=6, padding_type='reflect'):
        assert(n_blocks >= 0)
        super(ResnetGenerator, self).__init__()
        self.input_nc = input_nc
        self.output_nc = output_nc
        self.ngf = ngf
        if type(norm_layer) == functools.partial:
            use_bias = norm_layer.func == nn.InstanceNorm2d
        else:
            use_bias = norm_layer == nn.InstanceNorm2d

        model = [nn.ReflectionPad2d(3),
                 nn.Conv2d(input_nc, ngf, kernel_size=7, padding=0,
                           bias=use_bias),
                 norm_layer(ngf),
                 nn.ReLU(True)]

        n_downsampling = 2
        for i in range(n_downsampling):
            mult = 2**i
            model += [nn.Conv2d(ngf * mult, ngf * mult * 2, kernel_size=3,
                                stride=2, padding=1, bias=use_bias),
                      norm_layer(ngf * mult * 2),
                      nn.ReLU(True)]

        mult = 2**n_downsampling
        for i in range(n_blocks):
            model += [ResnetBlock(ngf * mult, padding_type=padding_type, norm_layer=norm_layer, use_dropout=use_dropout, use_bias=use_bias)]

        for i in range(n_downsampling):
            mult = 2**(n_downsampling - i)
            model += [nn.ConvTranspose2d(ngf * mult, int(ngf * mult / 2),
                                         kernel_size=3, stride=2,
                                         padding=1, output_padding=1,
                                         bias=use_bias),
                      norm_layer(int(ngf * mult / 2)),
                      nn.ReLU(True)]
        model += [nn.ReflectionPad2d(3)]
        model += [nn.Conv2d(ngf, output_nc, kernel_size=7, padding=0)]
        model += [nn.Tanh()]

        self.model = nn.Sequential(*model)

    def forward(self, input):
        return self.model(input)


# Define a resnet block
class ResnetBlock(nn.Module):
    def __init__(self, dim, padding_type, norm_layer, use_dropout, use_bias):
        super(ResnetBlock, self).__init__()
        self.conv_block = self.build_conv_block(dim, padding_type, norm_layer, use_dropout, use_bias)

    def build_conv_block(self, dim, padding_type, norm_layer, use_dropout, use_bias):
        conv_block = []
        p = 0
        if padding_type == 'reflect':
            conv_block += [nn.ReflectionPad2d(1)]
        elif padding_type == 'replicate':
            conv_block += [nn.ReplicationPad2d(1)]
        elif padding_type == 'zero':
            p = 1
        else:
            raise NotImplementedError('padding [%s] is not implemented' % padding_type)

        conv_block += [nn.Conv2d(dim, dim, kernel_size=3, padding=p, bias=use_bias),
                       norm_layer(dim),
                       nn.ReLU(True)]
        if use_dropout:
            conv_block += [nn.Dropout(0.5)]

        p = 0
        if padding_type == 'reflect':
            conv_block += [nn.ReflectionPad2d(1)]
        elif padding_type == 'replicate':
            conv_block += [nn.ReplicationPad2d(1)]
        elif padding_type == 'zero':
            p = 1
        else:
            raise NotImplementedError('padding [%s] is not implemented' % padding_type)
        conv_block += [nn.Conv2d(dim, dim, kernel_size=3, padding=p, bias=use_bias),
                       norm_layer(dim)]

        return nn.Sequential(*conv_block)

    def forward(self, x):
        out = x + self.conv_block(x)
        return out


# Defines the Unet generator.
# |num_downs|: number of downsamplings in UNet. For example,
# if |num_downs| == 7, image of size 128x128 will become of size 1x1
# at the bottleneck
class UnetGenerator(nn.Module):
    def __init__(self, input_nc, output_nc, num_downs, ngf=64,
                 norm_layer=nn.BatchNorm2d, use_dropout=False):
        super(UnetGenerator, self).__init__()

        # construct unet structure
        unet_block = UnetSkipConnectionBlock(ngf * 8, ngf * 8, input_nc=None, submodule=None, norm_layer=norm_layer, innermost=True)
        for i in range(num_downs - 5):
            unet_block = UnetSkipConnectionBlock(ngf * 8, ngf * 8, input_nc=None, submodule=unet_block, norm_layer=norm_layer, use_dropout=use_dropout)
        unet_block = UnetSkipConnectionBlock(ngf * 4, ngf * 8, input_nc=None, submodule=unet_block, norm_layer=norm_layer)
        unet_block = UnetSkipConnectionBlock(ngf * 2, ngf * 4, input_nc=None, submodule=unet_block, norm_layer=norm_layer)
        unet_block = UnetSkipConnectionBlock(ngf, ngf * 2, input_nc=None, submodule=unet_block, norm_layer=norm_layer)
        unet_block = UnetSkipConnectionBlock(output_nc, ngf, input_nc=input_nc, submodule=unet_block, outermost=True, norm_layer=norm_layer)

        self.model = unet_block

    def forward(self, input):
        return self.model(input)


# Defines the submodule with skip connection.
# X -------------------identity---------------------- X
#   |-- downsampling -- |submodule| -- upsampling --|
class UnetSkipConnectionBlock(nn.Module):
    def __init__(self, outer_nc, inner_nc, input_nc=None,
                 submodule=None, outermost=False, innermost=False, norm_layer=nn.BatchNorm2d, use_dropout=False):
        super(UnetSkipConnectionBlock, self).__init__()
        self.outermost = outermost
        if type(norm_layer) == functools.partial:
            use_bias = norm_layer.func == nn.InstanceNorm2d
        else:
            use_bias = norm_layer == nn.InstanceNorm2d
        if input_nc is None:
            input_nc = outer_nc
        downconv = nn.Conv2d(input_nc, inner_nc, kernel_size=4,
                             stride=2, padding=1, bias=use_bias)
        downrelu = nn.LeakyReLU(0.2, True)
        downnorm = norm_layer(inner_nc)
        uprelu = nn.ReLU(True)
        upnorm = norm_layer(outer_nc)

        if outermost:
            upconv = nn.ConvTranspose2d(inner_nc * 2, outer_nc,
                                        kernel_size=4, stride=2,
                                        padding=1)
            down = [downconv]
            up = [uprelu, upconv, nn.Tanh()]
            model = down + [submodule] + up
        elif innermost:
            upconv = nn.ConvTranspose2d(inner_nc, outer_nc,
                                        kernel_size=4, stride=2,
                                        padding=1, bias=use_bias)
            down = [downrelu, downconv]
            up = [uprelu, upconv, upnorm]
            model = down + up
        else:
            upconv = nn.ConvTranspose2d(inner_nc * 2, outer_nc,
                                        kernel_size=4, stride=2,
                                        padding=1, bias=use_bias)
            down = [downrelu, downconv, downnorm]
            up = [uprelu, upconv, upnorm]

            if use_dropout:
                model = down + [submodule] + up + [nn.Dropout(0.5)]
            else:
                model = down + [submodule] + up

        self.model = nn.Sequential(*model)

    def forward(self, x):
        if self.outermost:
            return self.model(x)
        else:
            return torch.cat([x, self.model(x)], 1)


# Defines the PatchGAN discriminator with the specified arguments.
class NLayerDiscriminator(nn.Module):
    def __init__(self, input_nc, ndf=64, n_layers=3, norm_layer=nn.BatchNorm2d, use_sigmoid=False):
        super(NLayerDiscriminator, self).__init__()
        if type(norm_layer) == functools.partial:
            use_bias = norm_layer.func == nn.InstanceNorm2d
        else:
            use_bias = norm_layer == nn.InstanceNorm2d

        kw = 4
        padw = 1
        sequence = [
            nn.Conv2d(input_nc, ndf, kernel_size=kw, stride=2, padding=padw),
            nn.LeakyReLU(0.2, True)
        ]

        nf_mult = 1
        nf_mult_prev = 1
        for n in range(1, n_layers):
            nf_mult_prev = nf_mult
            nf_mult = min(2**n, 8)
            sequence += [
                nn.Conv2d(ndf * nf_mult_prev, ndf * nf_mult,
                          kernel_size=kw, stride=2, padding=padw, bias=use_bias),
                norm_layer(ndf * nf_mult),
                nn.LeakyReLU(0.2, True)
            ]

        nf_mult_prev = nf_mult
        nf_mult = min(2**n_layers, 8)
        sequence += [
            nn.Conv2d(ndf * nf_mult_prev, ndf * nf_mult,
                      kernel_size=kw, stride=1, padding=padw, bias=use_bias),
            norm_layer(ndf * nf_mult),
            nn.LeakyReLU(0.2, True)
        ]

        sequence += [nn.Conv2d(ndf * nf_mult, 1, kernel_size=kw, stride=1, padding=padw)]

        if use_sigmoid:
            sequence += [nn.Sigmoid()]

        self.model = nn.Sequential(*sequence)

    def forward(self, input):
        return self.model(input)


class PixelDiscriminator(nn.Module):
    def __init__(self, input_nc, ndf=64, norm_layer=nn.BatchNorm2d, use_sigmoid=False):
        super(PixelDiscriminator, self).__init__()
        if type(norm_layer) == functools.partial:
            use_bias = norm_layer.func == nn.InstanceNorm2d
        else:
            use_bias = norm_layer == nn.InstanceNorm2d

        self.net = [
            nn.Conv2d(input_nc, ndf, kernel_size=1, stride=1, padding=0),
            nn.LeakyReLU(0.2, True),
            nn.Conv2d(ndf, ndf * 2, kernel_size=1, stride=1, padding=0, bias=use_bias),
            norm_layer(ndf * 2),
            nn.LeakyReLU(0.2, True),
            nn.Conv2d(ndf * 2, 1, kernel_size=1, stride=1, padding=0, bias=use_bias)]

        if use_sigmoid:
            self.net.append(nn.Sigmoid())

        self.net = nn.Sequential(*self.net)

    def forward(self, input):
        return self.net(input)


##############################################################################
# Basic network model 
##############################################################################
def define_splitG(img_nc, aus_nc, ngf, use_dropout=False, norm='instance', init_type='normal', init_gain=0.02, gpu_ids=[]):
    norm_layer = get_norm_layer(norm_type=norm)
    net_img_au = SplitGenerator(img_nc, aus_nc, ngf, norm_layer=norm_layer, use_dropout=use_dropout, n_blocks=6)
    return init_net(net_img_au, init_type, init_gain, gpu_ids)


def define_splitD(input_nc, aus_nc, image_size, ndf, norm='instance', init_type='normal', init_gain=0.02, gpu_ids=[]):
    norm_layer = get_norm_layer(norm_type=norm)
    net_dis_aus = SplitDiscriminator(input_nc, aus_nc, image_size, ndf, n_layers=6, norm_layer=norm_layer)
    return init_net(net_dis_aus, init_type, init_gain, gpu_ids)


class SplitGenerator(nn.Module):
    def __init__(self, img_nc, aus_nc, ngf=64, norm_layer=nn.BatchNorm2d, use_dropout=False, n_blocks=6, padding_type='zero'):
        assert(n_blocks >= 0)
        super(SplitGenerator, self).__init__()
        self.input_nc = img_nc + aus_nc
        self.ngf = ngf
        if type(norm_layer) == functools.partial:
            use_bias = norm_layer.func == nn.InstanceNorm2d
        else:
            use_bias = norm_layer == nn.InstanceNorm2d

        model = [nn.Conv2d(self.input_nc, ngf, kernel_size=7, stride=1, padding=3, 
                           bias=use_bias),
                 norm_layer(ngf),
                 nn.ReLU(True)]

        n_downsampling = 2
        for i in range(n_downsampling):
            mult = 2**i
            model += [nn.Conv2d(ngf * mult, ngf * mult * 2, \
                                kernel_size=4, stride=2, padding=1, \
                                bias=use_bias),
                      norm_layer(ngf * mult * 2),
                      nn.ReLU(True)]

        mult = 2**n_downsampling
        for i in range(n_blocks):
            model += [ResnetBlock(ngf * mult, padding_type=padding_type, norm_layer=norm_layer, use_dropout=use_dropout, use_bias=use_bias)]

        for i in range(n_downsampling):
            mult = 2**(n_downsampling - i)
            model += [nn.ConvTranspose2d(ngf * mult, int(ngf * mult / 2),
                                         kernel_size=4, stride=2, padding=1,
                                         bias=use_bias),
                      norm_layer(int(ngf * mult / 2)),
                      nn.ReLU(True)]

        self.model = nn.Sequential(*model)
        # color mask generator top
        color_top = []
        color_top += [nn.Conv2d(ngf, img_nc, kernel_size=7, stride=1, padding=3, bias=False),
                        nn.Tanh()]
        self.color_top = nn.Sequential(*color_top)
        # AUs mask generator top 
        au_top = []
        au_top += [nn.Conv2d(ngf, 1, kernel_size=7, stride=1, padding=3, bias=False),
                    nn.Sigmoid()]
        self.au_top = nn.Sequential(*au_top)

        # from torchsummary import summary
        # summary(self.model.to("cuda"), (20, 128, 128))
        # summary(self.color_top.to("cuda"), (64, 128, 128))
        # summary(self.au_top.to("cuda"), (64, 128, 128))
        # assert False

    def forward(self, img, au):
        # replicate AUs vector to match image shap and concate to construct input 
        sparse_au = au.unsqueeze(2).unsqueeze(3)
        sparse_au = sparse_au.expand(sparse_au.size(0), sparse_au.size(1), img.size(2), img.size(3))
        self.input_img_au = torch.cat([img, sparse_au], dim=1)

        embed_features = self.model(self.input_img_au)

        return self.color_top(embed_features), self.au_top(embed_features), embed_features


class SplitDiscriminator(nn.Module):
    def __init__(self, input_nc, aus_nc, image_size=128, ndf=64, n_layers=6, norm_layer=nn.BatchNorm2d):
        super(SplitDiscriminator, self).__init__()
        if type(norm_layer) == functools.partial:
            use_bias = norm_layer.func == nn.InstanceNorm2d
        else:
            use_bias = norm_layer == nn.InstanceNorm2d

        kw = 4
        padw = 1
        sequence = [
            nn.Conv2d(input_nc, ndf, kernel_size=kw, stride=2, padding=padw),
            nn.LeakyReLU(0.01, True)
        ]

        cur_dim = ndf
        for n in range(1, n_layers):
            sequence += [
                nn.Conv2d(cur_dim, 2 * cur_dim,
                          kernel_size=kw, stride=2, padding=padw, bias=use_bias),
                nn.LeakyReLU(0.01, True)
            ]
            cur_dim = 2 * cur_dim

        self.model = nn.Sequential(*sequence)
        # patch discriminator top
        self.dis_top = nn.Conv2d(cur_dim, 1, kernel_size=kw-1, stride=1, padding=padw, bias=False)
        # AUs classifier top 
        k_size = int(image_size / (2 ** n_layers))
        self.aus_top = nn.Conv2d(cur_dim, aus_nc, kernel_size=k_size, stride=1, bias=False)

        # from torchsummary import summary
        # summary(self.model.to("cuda"), (3, 128, 128))

    def forward(self, img):
        embed_features = self.model(img)
        pred_map = self.dis_top(embed_features)
        pred_aus = self.aus_top(embed_features)
        return pred_map.squeeze(), pred_aus.squeeze()


# https://github.com/jxgu1016/Total_Variation_Loss.pytorch/blob/master/TVLoss.py
class TVLoss(nn.Module):
    def __init__(self, TVLoss_weight=1):
        super(TVLoss,self).__init__()
        self.TVLoss_weight = TVLoss_weight

    def forward(self,x):
        batch_size = x.size()[0]
        h_x = x.size()[2]
        w_x = x.size()[3]
        count_h = self._tensor_size(x[:,:,1:,:])
        count_w = self._tensor_size(x[:,:,:,1:])
        h_tv = torch.pow((x[:,:,1:,:]-x[:,:,:h_x-1,:]),2).sum()
        w_tv = torch.pow((x[:,:,:,1:]-x[:,:,:,:w_x-1]),2).sum()
        return self.TVLoss_weight*2*(h_tv/count_h+w_tv/count_w)/batch_size

    def _tensor_size(self,t):
        return t.size()[1]*t.size()[2]*t.size()[3]