import torch
import torch.nn.functional as F
import numpy as np
import matplotlib.pyplot as plt

import torchext
import co


class TimedModule(torch.nn.Module):
    def __init__(self, mod_name):
        super().__init__()
        self.mod_name = mod_name

    def tforward(self, *args, **kwargs):
        raise Exception('not implemented')

    def forward(self, *args, **kwargs):
        torch.cuda.synchronize()
        with co.gtimer.Ctx(self.mod_name):
            x = self.tforward(*args, **kwargs)
            torch.cuda.synchronize()
        return x


class PosOutput(TimedModule):
    def __init__(self, channels_in, type, im_height, im_width, alpha=1, beta=0, gamma=1, offset=0):
        super().__init__(mod_name='PosOutput')
        self.im_width = im_width
        self.im_width = im_width

        if type == 'pos':
            self.layer = torch.nn.Sequential(
                torch.nn.Conv2d(channels_in, 1, kernel_size=3, padding=1),
                SigmoidAffine(alpha=alpha, beta=beta, gamma=gamma, offset=offset)
            )
        elif type == 'pos_row':
            self.layer = torch.nn.Sequential(
                MultiLinear(im_height, channels_in, 1),
                SigmoidAffine(alpha=alpha, beta=beta, gamma=gamma, offset=offset)
            )

        self.u_pos = None

    def tforward(self, x):
        if self.u_pos is None:
            self.u_pos = torch.arange(x.shape[3], dtype=torch.float32).view(1, 1, 1, -1)
        self.u_pos = self.u_pos.to(x.device)
        pos = self.layer(x)
        disp = self.u_pos - pos
        return disp


class OutputLayerFactory(object):
    '''
    Define type of output
    type options:
      linear: apply only conv channel, used for the edge decoder
      disp: estimate the disparity
      disp_row: independently estimate the disparity per row
      pos: estimate the absolute location
      pos_row: independently estimate the absolute location per row
    '''

    def __init__(self, type='disp', params={}):
        self.type = type
        self.params = params

    def __call__(self, channels_in, imsize):

        if self.type == 'linear':
            return torch.nn.Conv2d(channels_in, 1, kernel_size=3, padding=1)

        elif self.type == 'disp':
            return torch.nn.Sequential(
                torch.nn.Conv2d(channels_in, 1, kernel_size=3, padding=1),
                SigmoidAffine(**self.params)
            )

        elif self.type == 'disp_row':
            return torch.nn.Sequential(
                MultiLinear(imsize[0], channels_in, 1),
                SigmoidAffine(**self.params)
            )

        elif self.type == 'pos' or self.type == 'pos_row':
            return PosOutput(channels_in, **self.params)

        else:
            raise Exception('unknown output layer type')


class SigmoidAffine(TimedModule):
    def __init__(self, alpha=1, beta=0, gamma=1, offset=0):
        super().__init__(mod_name='SigmoidAffine')
        self.alpha = alpha
        self.beta = beta
        self.gamma = gamma
        self.offset = offset

    def tforward(self, x):
        return torch.sigmoid(x / self.gamma - self.offset) * self.alpha + self.beta


class MultiLinear(TimedModule):
    def __init__(self, n, channels_in, channels_out):
        super().__init__(mod_name='MultiLinear')
        self.channels_out = channels_out
        self.mods = torch.nn.ModuleList()
        for idx in range(n):
            self.mods.append(torch.nn.Linear(channels_in, channels_out))

    def tforward(self, x):
        x = x.permute(2, 0, 3, 1)  # BxCxHxW => HxBxWxC
        y = x.new_empty(*x.shape[:-1], self.channels_out)
        for hidx in range(x.shape[0]):
            y[hidx] = self.mods[hidx](x[hidx])
        y = y.permute(1, 3, 0, 2)  # HxBxWxC => BxCxHxW
        return y


class DispNetS(TimedModule):
    '''
    Disparity Decoder based on DispNetS
    '''

    def __init__(self, channels_in, imsizes, output_facs, output_ms=True, coordconv=False, weight_init=False,
                 channel_multiplier=1):
        super(DispNetS, self).__init__(mod_name='DispNetS')

        self.output_ms = output_ms
        self.coordconv = coordconv

        conv_planes = channel_multiplier * np.array([32, 64, 128, 256, 512, 512, 512])
        self.conv1 = self.downsample_conv(channels_in, conv_planes[0], kernel_size=7)
        self.conv2 = self.downsample_conv(conv_planes[0], conv_planes[1], kernel_size=5)
        self.conv3 = self.downsample_conv(conv_planes[1], conv_planes[2])
        self.conv4 = self.downsample_conv(conv_planes[2], conv_planes[3])
        self.conv5 = self.downsample_conv(conv_planes[3], conv_planes[4])
        self.conv6 = self.downsample_conv(conv_planes[4], conv_planes[5])
        self.conv7 = self.downsample_conv(conv_planes[5], conv_planes[6])

        upconv_planes = channel_multiplier * np.array([512, 512, 256, 128, 64, 32, 16])
        self.upconv7 = self.upconv(conv_planes[6], upconv_planes[0])
        self.upconv6 = self.upconv(upconv_planes[0], upconv_planes[1])
        self.upconv5 = self.upconv(upconv_planes[1], upconv_planes[2])
        self.upconv4 = self.upconv(upconv_planes[2], upconv_planes[3])
        self.upconv3 = self.upconv(upconv_planes[3], upconv_planes[4])
        self.upconv2 = self.upconv(upconv_planes[4], upconv_planes[5])
        self.upconv1 = self.upconv(upconv_planes[5], upconv_planes[6])

        self.iconv7 = self.conv(upconv_planes[0] + conv_planes[5], upconv_planes[0])
        self.iconv6 = self.conv(upconv_planes[1] + conv_planes[4], upconv_planes[1])
        self.iconv5 = self.conv(upconv_planes[2] + conv_planes[3], upconv_planes[2])
        self.iconv4 = self.conv(upconv_planes[3] + conv_planes[2], upconv_planes[3])
        self.iconv3 = self.conv(1 + upconv_planes[4] + conv_planes[1], upconv_planes[4])
        self.iconv2 = self.conv(1 + upconv_planes[5] + conv_planes[0], upconv_planes[5])
        self.iconv1 = self.conv(1 + upconv_planes[6], upconv_planes[6])

        if isinstance(output_facs, list):
            self.predict_disp4 = output_facs[3](upconv_planes[3], imsizes[3])
            self.predict_disp3 = output_facs[2](upconv_planes[4], imsizes[2])
            self.predict_disp2 = output_facs[1](upconv_planes[5], imsizes[1])
            self.predict_disp1 = output_facs[0](upconv_planes[6], imsizes[0])
        else:
            self.predict_disp4 = output_facs(upconv_planes[3], imsizes[3])
            self.predict_disp3 = output_facs(upconv_planes[4], imsizes[2])
            self.predict_disp2 = output_facs(upconv_planes[5], imsizes[1])
            self.predict_disp1 = output_facs(upconv_planes[6], imsizes[0])

    def init_weights(self):
        for m in self.modules():
            if isinstance(m, torch.nn.Conv2d) or isinstance(m, torch.nn.ConvTranspose2d):
                torch.nn.init.xavier_uniform_(m.weight, gain=0.1)
                if m.bias is not None:
                    torch.nn.init.zeros_(m.bias)

    def downsample_conv(self, in_planes, out_planes, kernel_size=3):
        if self.coordconv:
            conv = torchext.CoordConv2d(in_planes, out_planes, kernel_size=kernel_size, stride=2,
                                        padding=(kernel_size - 1) // 2)
        else:
            conv = torch.nn.Conv2d(in_planes, out_planes, kernel_size=kernel_size, stride=2,
                                   padding=(kernel_size - 1) // 2)
        return torch.nn.Sequential(
            conv,
            torch.nn.ReLU(inplace=True),
            torch.nn.Conv2d(out_planes, out_planes, kernel_size=kernel_size, padding=(kernel_size - 1) // 2),
            torch.nn.ReLU(inplace=True)
        )

    def conv(self, in_planes, out_planes):
        return torch.nn.Sequential(
            torch.nn.Conv2d(in_planes, out_planes, kernel_size=3, padding=1),
            torch.nn.ReLU(inplace=True)
        )

    def upconv(self, in_planes, out_planes):
        return torch.nn.Sequential(
            torch.nn.ConvTranspose2d(in_planes, out_planes, kernel_size=3, stride=2, padding=1, output_padding=1),
            torch.nn.ReLU(inplace=True)
        )

    def crop_like(self, input, ref):
        assert (input.size(2) >= ref.size(2) and input.size(3) >= ref.size(3))
        return input[:, :, :ref.size(2), :ref.size(3)]

    def tforward(self, x):
        out_conv1 = self.conv1(x)
        out_conv2 = self.conv2(out_conv1)
        out_conv3 = self.conv3(out_conv2)
        out_conv4 = self.conv4(out_conv3)
        out_conv5 = self.conv5(out_conv4)
        out_conv6 = self.conv6(out_conv5)
        out_conv7 = self.conv7(out_conv6)

        out_upconv7 = self.crop_like(self.upconv7(out_conv7), out_conv6)
        concat7 = torch.cat((out_upconv7, out_conv6), 1)
        out_iconv7 = self.iconv7(concat7)

        out_upconv6 = self.crop_like(self.upconv6(out_iconv7), out_conv5)
        concat6 = torch.cat((out_upconv6, out_conv5), 1)
        out_iconv6 = self.iconv6(concat6)

        out_upconv5 = self.crop_like(self.upconv5(out_iconv6), out_conv4)
        concat5 = torch.cat((out_upconv5, out_conv4), 1)
        out_iconv5 = self.iconv5(concat5)

        out_upconv4 = self.crop_like(self.upconv4(out_iconv5), out_conv3)
        concat4 = torch.cat((out_upconv4, out_conv3), 1)
        out_iconv4 = self.iconv4(concat4)
        disp4 = self.predict_disp4(out_iconv4)

        out_upconv3 = self.crop_like(self.upconv3(out_iconv4), out_conv2)
        disp4_up = self.crop_like(
            torch.nn.functional.interpolate(disp4, scale_factor=2, mode='bilinear', align_corners=False), out_conv2)
        concat3 = torch.cat((out_upconv3, out_conv2, disp4_up), 1)
        out_iconv3 = self.iconv3(concat3)
        disp3 = self.predict_disp3(out_iconv3)

        out_upconv2 = self.crop_like(self.upconv2(out_iconv3), out_conv1)
        disp3_up = self.crop_like(
            torch.nn.functional.interpolate(disp3, scale_factor=2, mode='bilinear', align_corners=False), out_conv1)
        concat2 = torch.cat((out_upconv2, out_conv1, disp3_up), 1)
        out_iconv2 = self.iconv2(concat2)
        disp2 = self.predict_disp2(out_iconv2)

        out_upconv1 = self.crop_like(self.upconv1(out_iconv2), x)
        disp2_up = self.crop_like(
            torch.nn.functional.interpolate(disp2, scale_factor=2, mode='bilinear', align_corners=False), x)
        concat1 = torch.cat((out_upconv1, disp2_up), 1)
        out_iconv1 = self.iconv1(concat1)
        disp1 = self.predict_disp1(out_iconv1)

        if self.output_ms:
            return disp1, disp2, disp3, disp4
        else:
            return disp1


class DispNetShallow(DispNetS):
    '''
    Edge Decoder based on DispNetS with fewer layers
    '''

    def __init__(self, channels_in, imsizes, output_facs, output_ms=True, coordconv=False, weight_init=False):
        super(DispNetShallow, self).__init__(channels_in, imsizes, output_facs, output_ms, coordconv, weight_init)
        self.mod_name = 'DispNetShallow'
        conv_planes = [32, 64, 128, 256, 512, 512, 512]
        upconv_planes = [512, 512, 256, 128, 64, 32, 16]
        self.iconv3 = self.conv(upconv_planes[4] + conv_planes[1], upconv_planes[4])

    def tforward(self, x):
        out_conv1 = self.conv1(x)
        out_conv2 = self.conv2(out_conv1)
        out_conv3 = self.conv3(out_conv2)

        out_upconv3 = self.crop_like(self.upconv3(out_conv3), out_conv2)
        concat3 = torch.cat((out_upconv3, out_conv2), 1)
        out_iconv3 = self.iconv3(concat3)
        disp3 = self.predict_disp3(out_iconv3)

        out_upconv2 = self.crop_like(self.upconv2(out_iconv3), out_conv1)
        disp3_up = self.crop_like(
            torch.nn.functional.interpolate(disp3, scale_factor=2, mode='bilinear', align_corners=False), out_conv1)
        concat2 = torch.cat((out_upconv2, out_conv1, disp3_up), 1)
        out_iconv2 = self.iconv2(concat2)
        disp2 = self.predict_disp2(out_iconv2)

        out_upconv1 = self.crop_like(self.upconv1(out_iconv2), x)
        disp2_up = self.crop_like(
            torch.nn.functional.interpolate(disp2, scale_factor=2, mode='bilinear', align_corners=False), x)
        concat1 = torch.cat((out_upconv1, disp2_up), 1)
        out_iconv1 = self.iconv1(concat1)
        disp1 = self.predict_disp1(out_iconv1)

        if self.output_ms:
            return disp1, disp2, disp3
        else:
            return disp1


class DispEdgeDecoders(TimedModule):
    '''
    Disparity Decoder and Edge Decoder
    '''

    def __init__(self, *args, max_disp=128, **kwargs):
        super(DispEdgeDecoders, self).__init__(mod_name='DispEdgeDecoders')

        output_facs = [
            OutputLayerFactory(type='disp', params={'alpha': max_disp / (2 ** s), 'beta': 0, 'gamma': 1, 'offset': 3})
            for s in range(4)]
        self.disp_decoder = DispNetS(*args, output_facs=output_facs, **kwargs)

        output_facs = [OutputLayerFactory(type='linear') for s in range(4)]
        self.edge_decoder = DispNetShallow(*args, output_facs=output_facs, **kwargs)

    def tforward(self, x):
        disp = self.disp_decoder(x)
        edge = self.edge_decoder(x)
        return disp, edge


class DispToDepth(TimedModule):
    def __init__(self, focal_length, baseline):
        super().__init__(mod_name='DispToDepth')
        self.baseline_focal_length = baseline * focal_length

    def tforward(self, disp):
        disp = torch.nn.functional.relu(disp) + 1e-12
        depth = self.baseline_focal_length / disp
        return depth


class PosToDepth(DispToDepth):
    def __init__(self, focal_length, baseline, im_height, im_width):
        super().__init__(focal_length, baseline)
        self.mod_name = 'PosToDepth'

        self.im_height = im_height
        self.im_width = im_width
        self.u_pos = torch.arange(im_width, dtype=torch.float32).view(1, 1, 1, -1)

    def tforward(self, pos):
        self.u_pos = self.u_pos.to(pos.device)
        disp = self.u_pos - pos
        return super().forward(disp)


class RectifiedPatternSimilarityLoss(TimedModule):
    '''
    Photometric Loss
    '''

    def __init__(self, im_height, im_width, pattern, loss_type='census_sad', loss_eps=0.5):
        super().__init__(mod_name='RectifiedPatternSimilarityLoss')
        self.im_height = im_height
        self.im_width = im_width
        self.pattern = pattern.mean(dim=1, keepdim=True).contiguous()

        u, v = np.meshgrid(range(im_width), range(im_height))
        uv0 = np.stack((u, v), axis=2).reshape(-1, 1)
        uv0 = uv0.astype(np.float32).reshape(1, -1, 2)
        self.uv0 = torch.from_numpy(uv0)

        self.loss_type = loss_type
        self.loss_eps = loss_eps

    def tforward(self, disp0, im, std=None):
        self.pattern = self.pattern.to(disp0.device)
        self.uv0 = self.uv0.to(disp0.device)

        uv0 = self.uv0.expand(disp0.shape[0], *self.uv0.shape[1:])
        uv1 = torch.empty_like(uv0)
        uv1[..., 0] = uv0[..., 0] - disp0.contiguous().view(disp0.shape[0], -1)
        uv1[..., 1] = uv0[..., 1]

        uv1[..., 0] = 2 * (uv1[..., 0] / (self.im_width - 1) - 0.5)
        uv1[..., 1] = 2 * (uv1[..., 1] / (self.im_height - 1) - 0.5)
        uv1 = uv1.view(-1, self.im_height, self.im_width, 2).clone()
        pattern = self.pattern.expand(disp0.shape[0], *self.pattern.shape[1:])
        pattern_proj = torch.nn.functional.grid_sample(pattern, uv1, padding_mode='border')
        mask = torch.ones_like(im)
        if std is not None:
            mask = mask * std

        diff = torchext.photometric_loss(pattern_proj.contiguous(), im.contiguous(), 9, self.loss_type, self.loss_eps)
        val = (mask * diff).sum() / mask.sum()
        return val, pattern_proj


class DisparityLoss(TimedModule):
    '''
    Disparity Loss
    '''

    def __init__(self):
        super().__init__(mod_name='DisparityLoss')
        self.sobel = SobelFilter(norm=False)

        # if not edge_gt:
        self.b0 = 0.0503428816795
        self.b1 = 1.07274045944
        # else:
        #  self.b0=0.0587115108967
        #  self.b1=1.51931190491

    def tforward(self, disp, edge=None):
        self.sobel = self.sobel.to(disp.device)

        if edge is not None:
            grad = self.sobel(disp)
            grad = torch.sqrt(grad[:, 0:1, ...] ** 2 + grad[:, 1:2, ...] ** 2 + 1e-8)
            pdf = (1 - edge) / self.b0 * torch.exp(-torch.abs(grad) / self.b0) + \
                  edge / self.b1 * torch.exp(-torch.abs(grad) / self.b1)
            val = torch.mean(-torch.log(pdf.clamp(min=1e-4)))
        else:
            # on qifeng's data we don't have ambient info
            # therefore we supress edge everywhere
            grad = self.sobel(disp)
            grad = torch.sqrt(grad[:, 0:1, ...] ** 2 + grad[:, 1:2, ...] ** 2 + 1e-8)
            grad = torch.clamp(grad, 0, 1.0)
            val = torch.mean(grad)

        return val


class ProjectionBaseLoss(TimedModule):
    '''
    Base module of the Geometric Loss
    '''

    def __init__(self, K, Ki, im_height, im_width):
        super().__init__(mod_name='ProjectionBaseLoss')

        self.K = K.view(-1, 3, 3)

        self.im_height = im_height
        self.im_width = im_width

        u, v = np.meshgrid(range(im_width), range(im_height))
        uv = np.stack((u, v, np.ones_like(u)), axis=2).reshape(-1, 3)

        ray = uv @ Ki.numpy().T

        ray = ray.reshape(1, -1, 3).astype(np.float32)
        self.ray = torch.from_numpy(ray)

    def transform(self, xyz, R=None, t=None):
        if t is not None:
            bs = xyz.shape[0]
            xyz = xyz - t.reshape(bs, 1, 3)
        if R is not None:
            xyz = torch.bmm(xyz, R)
        return xyz

    def unproject(self, depth, R=None, t=None):
        self.ray = self.ray.to(depth.device)
        bs = depth.shape[0]

        xyz = depth.reshape(bs, -1, 1) * self.ray
        xyz = self.transform(xyz, R, t)
        return xyz

    def project(self, xyz, R, t):
        self.K = self.K.to(xyz.device)
        bs = xyz.shape[0]

        xyz = torch.bmm(xyz, R.transpose(1, 2))
        xyz = xyz + t.reshape(bs, 1, 3)

        Kt = self.K.transpose(1, 2).expand(bs, -1, -1)
        uv = torch.bmm(xyz, Kt)

        d = uv[:, :, 2:3]

        # avoid division by zero
        uv = uv[:, :, :2] / (torch.nn.functional.relu(d) + 1e-12)
        return uv, d

    def tforward(self, depth0, R0, t0, R1, t1):
        xyz = self.unproject(depth0, R0, t0)
        return self.project(xyz, R1, t1)


class ProjectionDepthSimilarityLoss(ProjectionBaseLoss):
    '''
    Geometric Loss
    '''

    def __init__(self, *args, clamp=-1):
        super().__init__(*args)
        self.mod_name = 'ProjectionDepthSimilarityLoss'
        self.clamp = clamp

    def fwd(self, depth0, depth1, R0, t0, R1, t1):
        uv1, d1 = super().tforward(depth0, R0, t0, R1, t1)

        uv1[..., 0] = 2 * (uv1[..., 0] / (self.im_width - 1) - 0.5)
        uv1[..., 1] = 2 * (uv1[..., 1] / (self.im_height - 1) - 0.5)
        uv1 = uv1.view(-1, self.im_height, self.im_width, 2).clone()

        depth10 = torch.nn.functional.grid_sample(depth1, uv1, padding_mode='border')

        diff = torch.abs(d1.view(-1) - depth10.view(-1))

        if self.clamp > 0:
            diff = torch.clamp(diff, 0, self.clamp)

        # return diff without clamping for debugging
        return diff.mean()

    def tforward(self, depth0, depth1, R0, t0, R1, t1):
        l0 = self.fwd(depth0, depth1, R0, t0, R1, t1)
        l1 = self.fwd(depth1, depth0, R1, t1, R0, t0)
        return l0 + l1


class LCN(TimedModule):
    '''
    Local Contract Normalization
    '''

    def __init__(self, radius, epsilon):
        super().__init__(mod_name='LCN')
        self.box_conv = torch.nn.Sequential(
            torch.nn.ReflectionPad2d(radius),
            torch.nn.Conv2d(1, 1, kernel_size=2 * radius + 1, bias=False)
        )
        self.box_conv[1].weight.requires_grad = False
        self.box_conv[1].weight.fill_(1.)

        self.epsilon = epsilon
        self.radius = radius

    def tforward(self, data):
        boxs = self.box_conv(data)

        avgs = boxs / (2 * self.radius + 1) ** 2
        boxs_n2 = boxs ** 2
        boxs_2n = self.box_conv(data ** 2)

        stds = torch.sqrt(boxs_2n / (2 * self.radius + 1) ** 2 - avgs ** 2 + 1e-6)
        stds = stds + self.epsilon

        return (data - avgs) / stds, stds


class SobelFilter(TimedModule):
    '''
    Sobel Filter
    '''

    def __init__(self, norm=False):
        super(SobelFilter, self).__init__(mod_name='SobelFilter')
        kx = np.array([[-5, -4, 0, 4, 5],
                       [-8, -10, 0, 10, 8],
                       [-10, -20, 0, 20, 10],
                       [-8, -10, 0, 10, 8],
                       [-5, -4, 0, 4, 5]]) / 240.0
        ky = kx.copy().transpose(1, 0)

        self.conv_x = torch.nn.Conv2d(1, 1, kernel_size=5, stride=1, padding=0, bias=False)
        self.conv_x.weight = torch.nn.Parameter(torch.from_numpy(kx).float().unsqueeze(0).unsqueeze(0))

        self.conv_y = torch.nn.Conv2d(1, 1, kernel_size=5, stride=1, padding=0, bias=False)
        self.conv_y.weight = torch.nn.Parameter(torch.from_numpy(ky).float().unsqueeze(0).unsqueeze(0))

        self.norm = norm

    def tforward(self, x):
        x = F.pad(x, (2, 2, 2, 2), "replicate")
        gx = self.conv_x(x)
        gy = self.conv_y(x)
        if self.norm:
            return torch.sqrt(gx ** 2 + gy ** 2 + 1e-8)
        else:
            return torch.cat((gx, gy), dim=1)
