import functools
import torch
import torch.nn as nn
import torch.nn.functional as F
import models.archs.arch_util as arch_util


class ResidualDenseBlock_5C(nn.Module):
    def __init__(self, nf=64, gc=32, bias=True):
        super(ResidualDenseBlock_5C, self).__init__()
        # gc: growth channel, i.e. intermediate channels
        self.conv1 = nn.Conv2d(nf, gc, 3, 1, 1, bias=bias)
        self.conv2 = nn.Conv2d(nf + gc, gc, 3, 1, 1, bias=bias)
        self.conv3 = nn.Conv2d(nf + 2 * gc, gc, 3, 1, 1, bias=bias)
        self.conv4 = nn.Conv2d(nf + 3 * gc, gc, 3, 1, 1, bias=bias)
        self.conv5 = nn.Conv2d(nf + 4 * gc, nf, 3, 1, 1, bias=bias)
        self.lrelu = nn.LeakyReLU(negative_slope=0.2, inplace=True)

        # initialization
        arch_util.initialize_weights([self.conv1, self.conv2, self.conv3, self.conv4, self.conv5],
                                     0.1)

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


class RRDB(nn.Module):
    '''Residual in Residual Dense Block'''

    def __init__(self, nf, gc=32):
        super(RRDB, self).__init__()
        self.RDB1 = ResidualDenseBlock_5C(nf, gc)
        self.RDB2 = ResidualDenseBlock_5C(nf, gc)
        self.RDB3 = ResidualDenseBlock_5C(nf, gc)

    def forward(self, x):
        out = self.RDB1(x)
        out = self.RDB2(out)
        out = self.RDB3(out)
        return out * 0.2 + x


class RRDBNet(nn.Module):
    def __init__(self, in_nc, out_nc, nf, nb_lo, nb_med, nb_hi, gc=32, interpolation_scale_factor=2):
        super(RRDBNet, self).__init__()
        nfmed = int(nf/2)
        nfhi = int(nf/8)
        gcmed = int(gc/2)
        gchi = int(gc/8)
        RRDB_block_f_lo = functools.partial(RRDB, nf=nf, gc=gc)
        RRDB_block_f_lo_med = functools.partial(RRDB, nf=nfmed, gc=gcmed)
        RRDB_block_f_lo_hi = functools.partial(RRDB, nf=nfhi, gc=gchi)

        self.conv_first = nn.Conv2d(in_nc, nf, 7, 1, padding=3, bias=True)
        self.RRDB_trunk_lo = arch_util.make_layer(RRDB_block_f_lo, nb_lo)
        self.trunk_conv = nn.Conv2d(nf, nf, 3, 1, 1, bias=True)
        self.lo_skip_conv1 = nn.Conv2d(nf, nf, 3, 1, padding=1, bias=True)
        self.lo_skip_conv2 = nn.Conv2d(nf, out_nc, 3, 1, 1, bias=True)

        #### upsampling
        self.upconv1 = nn.Conv2d(nf, nfmed, 3, 1, padding=1, bias=True)
        self.RRDB_trunk_med = arch_util.make_layer(RRDB_block_f_lo_med, nb_med)
        self.trunk_conv_med = nn.Conv2d(nfmed, nfmed, 3, 1, 1, bias=True)
        self.med_skip_conv1 = nn.Conv2d(nfmed, nfmed, 3, 1, padding=1, bias=True)
        self.med_skip_conv2 = nn.Conv2d(nfmed, out_nc, 3, 1, 1, bias=True)

        self.upconv2 = nn.Conv2d(nfmed, nfhi, 3, 1, padding=1, bias=True)
        self.RRDB_trunk_hi = arch_util.make_layer(RRDB_block_f_lo_hi, nb_hi)
        self.trunk_conv_hi = nn.Conv2d(nfhi, nfhi, 3, 1, 1, bias=True)
        self.HRconv = nn.Conv2d(nfhi, nfhi, 5, 1, padding=2, bias=True)
        self.conv_last = nn.Conv2d(nfhi, out_nc, 3, 1, 1, bias=True)

        self.lrelu = nn.LeakyReLU(negative_slope=0.2, inplace=True)

        self.interpolation_scale_factor = interpolation_scale_factor

    def forward(self, x):
        fea = self.conv_first(x)
        branch = self.trunk_conv(self.RRDB_trunk_lo(fea))
        fea = (fea + branch) / 2
        lo_skip = self.lo_skip_conv2(self.lrelu(self.lo_skip_conv1(fea)))

        fea = self.lrelu(self.upconv1(F.interpolate(fea, scale_factor=self.interpolation_scale_factor, mode='nearest')))
        branch = self.trunk_conv_med(self.RRDB_trunk_med(fea))
        fea = (fea + branch) / 2
        med_skip = self.med_skip_conv2(self.lrelu(self.med_skip_conv1(fea)))

        fea = self.lrelu(self.upconv2(F.interpolate(fea, scale_factor=self.interpolation_scale_factor, mode='nearest')))
        branch = self.trunk_conv_hi(self.RRDB_trunk_hi(fea))
        fea = (fea + branch) / 2
        out = self.conv_last(self.lrelu(self.HRconv(fea)))

        return out, med_skip, lo_skip