'''
New for ResNeXt:
1. Wider bottleneck
2. Add group for conv2
'''

import torch
import torch.nn as nn
import math

__all__ = ['SE_ResNeXt', 'se_resnext_50', 'se_resnext_101', 'se_resnext_152']

import logging
from .build import BACKBONE_REGISTRY
from rmclas.utils.checkpoint import get_missing_parameters_message, get_unexpected_parameters_message


logger = logging.getLogger(__name__)

class Bottleneck(nn.Module):
    expansion = 2

    def __init__(self, inplanes, planes, stride=1, downsample=None, num_group=32):
        super(Bottleneck, self).__init__()
        self.conv1 = nn.Conv2d(inplanes, planes*2, kernel_size=1, bias=False)
        self.bn1 = nn.BatchNorm2d(planes*2)
        self.conv2 = nn.Conv2d(planes*2, planes*2, kernel_size=3, stride=stride,
                               padding=1, bias=False, groups=num_group)
        self.bn2 = nn.BatchNorm2d(planes*2)
        self.conv3 = nn.Conv2d(planes*2, planes * 4, kernel_size=1, bias=False)
        self.bn3 = nn.BatchNorm2d(planes * 4)
        self.relu = nn.ReLU(inplace=True)
        self.downsample = downsample
        self.stride = stride
        self.planes = planes

        if planes == 64:
            self.globalAvgPool = nn.AvgPool2d(28, stride=1)
        elif planes == 128:
            self.globalAvgPool = nn.AvgPool2d(28, stride=1)
        elif planes == 256:
            self.globalAvgPool = nn.AvgPool2d(14, stride=1)
        elif planes == 512:
            self.globalAvgPool = nn.AvgPool2d(7, stride=1)
        self.fc1 = nn.Linear(in_features=planes * 4, out_features=round(planes / 4))
        self.fc2 = nn.Linear(in_features=round(planes / 4), out_features=planes * 4)
        self.sigmoid = nn.Sigmoid()

    def forward(self, x):
        residual = x

        out = self.conv1(x)
        out = self.bn1(out)
        out = self.relu(out)

        out = self.conv2(out)
        out = self.bn2(out)
        out = self.relu(out)

        out = self.conv3(out)
        out = self.bn3(out)

        if self.downsample is not None:
            residual = self.downsample(x)

        original_out = out
        print(self.planes)
        print(out.size())
        out = self.globalAvgPool(out)
        out = out.view(out.size(0), -1)
        print(out.size())
        out = self.fc1(out)
        out = self.relu(out)
        out = self.fc2(out)
        out = self.sigmoid(out)
        out = out.view(out.size(0), out.size(1), 1, 1)
        out = out * original_out

        print(out.size())
        print(residual.size())
        out += residual
        out = self.relu(out)

        return out


class SE_ResNeXt(nn.Module):

    def __init__(self, block, layers, num_classes=1000, num_group=32):
        self.inplanes = 64
        super(SE_ResNeXt, self).__init__()
        self.conv1 = nn.Conv2d(3, 64, kernel_size=7, stride=2, padding=3,
                               bias=False)
        self.bn1 = nn.BatchNorm2d(64)
        self.relu = nn.ReLU(inplace=True)
        self.maxpool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1)
        self.layer1 = self._make_layer(block, 64, layers[0], num_group)
        self.layer2 = self._make_layer(block, 128, layers[1], num_group, stride=2)
        self.layer3 = self._make_layer(block, 256, layers[2], num_group, stride=2)
        self.layer4 = self._make_layer(block, 512, layers[3], num_group, stride=2)
        self.avgpool = nn.AvgPool2d(7, stride=1)
        self.fc = nn.Linear(512 * block.expansion, num_classes)

        for m in self.modules():
            if isinstance(m, nn.Conv2d):
                n = m.kernel_size[0] * m.kernel_size[1] * m.out_channels
                m.weight.data.normal_(0, math.sqrt(2. / n))
            elif isinstance(m, nn.BatchNorm2d):
                m.weight.data.fill_(1)
                m.bias.data.zero_()

    def _make_layer(self, block, planes, blocks, num_group, stride=1):
        downsample = None
        if stride != 1 or self.inplanes != planes * block.expansion:
            downsample = nn.Sequential(
                nn.Conv2d(self.inplanes, planes * block.expansion,
                          kernel_size=1, stride=stride, bias=False),
                nn.BatchNorm2d(planes * block.expansion),
            )

        layers = []
        layers.append(block(self.inplanes, planes, stride, downsample, num_group=num_group))
        self.inplanes = planes * block.expansion
        for i in range(1, blocks):
            layers.append(block(self.inplanes, planes, num_group=num_group))

        return nn.Sequential(*layers)

    def forward(self, x):
        x = self.conv1(x)
        x = self.bn1(x)
        x = self.relu(x)
        x = self.maxpool(x)

        x = self.layer1(x)
        x = self.layer2(x)
        x = self.layer3(x)
        x = self.layer4(x)

        x = self.avgpool(x)
        #x = x.view(x.size(0), -1)
        #x = self.fc(x)

        return x

def se_resnext_50(**kwargs):
    """Constructs a ResNeXt-50 model.
    """
    model = SE_ResNeXt(Bottleneck, [3, 4, 6, 3], **kwargs)
    return model


def se_resnext_101(**kwargs):
    """Constructs a ResNeXt-101 model.
    """
    model = SE_ResNeXt(Bottleneck, [3, 4, 23, 3], **kwargs)
    return model


def se_resnext_152(**kwargs):
    """Constructs a ResNeXt-152 model.
    """
    model = SE_ResNeXt(Bottleneck, [3, 8, 36, 3], **kwargs)
    return model

@BACKBONE_REGISTRY.register()
def build_SEResNextV2_backbone(cfg):
    """
    Create a SEResNext instance from config.
    Returns:
        SEResNext: a :class:`SEResNext` instance.
    """
    # fmt: off
    pretrain      = cfg.MODEL.BACKBONE.PRETRAIN
    pretrain_path = cfg.MODEL.BACKBONE.PRETRAIN_PATH
    '''T             = cfg.MODEL.BACKBONE.T
    width_mult    = cfg.MODEL.BACKBONE.WIDTH_MULT'''
    # fmt: on

    model = se_resnext_50()

    if pretrain:
        # Load pretrain path if specifically
        if pretrain_path:
            try:
                o_state_dict = torch.load(pretrain_path, map_location=torch.device('cpu'))
                logger.info(f"Loading pretrained model from {pretrain_path}")
            except FileNotFoundError as e:
                logger.info(f'{pretrain_path} is not found! Please check this path.')
                raise e
            except KeyError as e:
                logger.info("State dict keys error! Please check the state dict.")
                raise e
            if 'state_dict' in o_state_dict:
                o_state_dict = o_state_dict['state_dict']
            state_dict = {}
            for k, v in o_state_dict.items():
                if 'module.' in k:
                    k = k.replace('module.', '')
                state_dict[k] = v
        else:
            raise ValueError("you should provide pretrain path, for we have no imagenet pretrain model to download")

        incompatible = model.load_state_dict(state_dict, strict=False)
        if incompatible.missing_keys:
            logger.info(
                get_missing_parameters_message(incompatible.missing_keys)
            )
        if incompatible.unexpected_keys:
            logger.info(
                get_unexpected_parameters_message(incompatible.unexpected_keys)
            )

    return model



