import numpy as np
import torch
import torch.nn as nn
import torchvision
from torchvision import models
from torch.autograd import Variable
import math
import torch.nn.utils.weight_norm as weightNorm

def calc_coeff(iter_num, high=1.0, low=0.0, alpha=10.0, max_iter=10000.0):
    return np.float(2.0 * (high - low) / (1.0 + np.exp(-alpha*iter_num / max_iter)) - (high - low) + low)

def init_weights(m):
    classname = m.__class__.__name__
    if classname.find('Conv2d') != -1:
        nn.init.kaiming_uniform_(m.weight)
        nn.init.zeros_(m.bias)
    elif classname.find('BatchNorm') != -1:
        nn.init.normal_(m.weight, 1.0, 0.02)
        nn.init.zeros_(m.bias)
    elif classname.find('Linear') != -1:
        nn.init.xavier_normal_(m.weight)
        nn.init.zeros_(m.bias)


res_dict = {"resnet18":models.resnet18, "resnet34":models.resnet34, "resnet50":models.resnet50,
"resnet101":models.resnet101, "resnet152":models.resnet152, "resnext50":models.resnext50_32x4d, "resnext101":models.resnext101_32x8d}


class ResBase(nn.Module):
    def __init__(self, res_name='resnet101', pretrained=False):
        super(ResBase, self).__init__()
        model_resnet = res_dict[res_name](pretrained=False)

        if pretrained:
            print("pretrained resnet50")
            model_resnet.load_state_dict(torch.load('/home/lyi7/scratch/resnet50.pth'))

        self.conv1 = model_resnet.conv1
        self.bn1 = model_resnet.bn1
        self.relu = model_resnet.relu
        self.maxpool = model_resnet.maxpool
        self.layer1 = model_resnet.layer1
        self.layer2 = model_resnet.layer2
        self.layer3 = model_resnet.layer3
        self.layer4 = model_resnet.layer4
        self.avgpool = model_resnet.avgpool
        self.in_features = model_resnet.fc.in_features

    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)
        return x



class feat_bootleneck(nn.Module):
    def __init__(self, feature_dim, bottleneck_dim=256, type="bn"):
        super().__init__()
        self.bn = nn.BatchNorm1d(bottleneck_dim, affine=True)
        self.relu = nn.ReLU(inplace=True)
        self.dropout = nn.Dropout(p=0.5)
        self.bottleneck = nn.Linear(feature_dim, bottleneck_dim)
        self.bottleneck.apply(init_weights)
        self.type = type

    def forward(self, x):
        x = self.bottleneck(x)
        if self.type == "bn":
            x = self.bn(x)
        out=x
        return out



class feat_classifier(nn.Module):
    def __init__(self, class_num, bottleneck_dim=256, type="wn"):
        super(feat_classifier, self).__init__()
        self.type = type
        if type == 'wn':
            self.fc = weightNorm(nn.Linear(bottleneck_dim, class_num), name="weight")
            self.fc.apply(init_weights)
        else:
            self.fc = nn.Linear(bottleneck_dim, class_num)
            self.fc.apply(init_weights)

    def forward(self, x):
        x = self.fc(x)
        return x