from __future__ import print_function
import os
import data
import torch
# import pickle
import metrics
import numpy as np
import torch.nn as nn
from datetime import datetime
from torch.optim import Adam, lr_scheduler
from models.NonBayesianModels.LeNet import LeNet
from models.NonBayesianModels.AlexNet import AlexNet
from stopping_crit import earlyStopping, energyBound, accuracyBound
from models.NonBayesianModels.ThreeConvThreeFC import ThreeConvThreeFC

# with (open("configuration.pkl", "rb")) as file:
#     while True:
#         try:
#             cfg = pickle.load(file)
#         except EOFError:
#             break

cfg = {
        "model": {"net_type": "lenet", "type": "freq", "size": 1,
                  "layer_type": "lrt", "activation_type": "softplus",
                  "priors": {
                      'prior_mu': 0,
                      'prior_sigma': 0.1,
                      'posterior_mu_initial': (0, 0.1),  # (mean,std) normal_
                      'posterior_rho_initial': (-5, 0.1),  # (mean,std) normal_
                      },
                  "n_epochs": 100,
                  "sens": 1e-9,
                  "energy_thrs": 100000,
                  "acc_thrs": 0.99,
                  "lr": 0.001,
                  "num_workers": 4,
                  "valid_size": 0.2,
                  "batch_size": 256,
                  "train_ens": 1,
                  "valid_ens": 1,
                  "beta_type": 0.1,  # 'Blundell','Standard',etc.
                  # Use float for const value
                  },
        #"data": "CIFAR10",
        "data": "MNIST",
        "stopping_crit": 1,
        "save": 1,
        "pickle_path": None,
}

# CUDA settings
device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")


def getModel(net_type, inputs, outputs, wide=cfg["model"]["size"]):
    if (net_type == 'lenet'):
        return LeNet(outputs, inputs, wide)
    elif (net_type == 'alexnet'):
        return AlexNet(outputs, inputs)
    elif (net_type == '3conv3fc'):
        return ThreeConvThreeFC(outputs, inputs)
    else:
        raise ValueError('Network should be either [LeNet / AlexNet / \
                3Conv3FC')


def train_model(net, optimizer, criterion, train_loader):
    train_loss = 0.0
    net.train()
    accs = []
    for datas, target in train_loader:
        data, target = datas.to(device), target.to(device)
        optimizer.zero_grad()
        output = net(data)
        loss = criterion(output, target)
        loss.backward()
        optimizer.step()
        train_loss += loss.item()*data.size(0)
        accs.append(metrics.acc(output.detach(), target))
    return train_loss, np.mean(accs)


def validate_model(net, criterion, valid_loader):
    valid_loss = 0.0
    net.eval()
    accs = []
    for datas, target in valid_loader:
        data, target = datas.to(device), target.to(device)
        output = net(data)
        loss = criterion(output, target)
        valid_loss += loss.item()*data.size(0)
        accs.append(metrics.acc(output.detach(), target))
    return valid_loss, np.mean(accs)


def run(dataset, net_type):

    # Hyper Parameter settings
    n_epochs = cfg["model"]["n_epochs"]
    lr = cfg["model"]["lr"]
    num_workers = cfg["model"]["num_workers"]
    valid_size = cfg["model"]["valid_size"]
    batch_size = cfg["model"]["batch_size"]

    trainset, testset, inputs, outputs = data.getDataset(dataset)
    train_loader, valid_loader, test_loader = data.getDataloader(
        trainset, testset, valid_size, batch_size, num_workers)
    net = getModel(net_type, inputs, outputs).to(device)

    ckpt_dir = f'checkpoints/{dataset}/frequentist'
    ckpt_name = f'checkpoints/{dataset}/frequentist/model_{net_type}_{cfg["model"]["size"]}'

    if not os.path.exists(ckpt_dir):
        os.makedirs(ckpt_dir, exist_ok=True)

    stp = cfg["stopping_crit"]
    sav = cfg["save"]

    criterion = nn.CrossEntropyLoss()
    optimizer = Adam(net.parameters(), lr=lr)
    lr_sched = lr_scheduler.ReduceLROnPlateau(optimizer, patience=6,
                                              verbose=True)
    # valid_loss_min = np.Inf
    # if stp == 2:
    early_stop = []
    train_data = []
    for epoch in range(1, n_epochs+1):

        train_loss, train_acc = train_model(net, optimizer, criterion,
                                            train_loader)
        valid_loss, valid_acc = validate_model(net, criterion, valid_loader)
        lr_sched.step(valid_loss)

        train_loss = train_loss/len(train_loader.dataset)
        valid_loss = valid_loss/len(valid_loader.dataset)

        train_data.append([epoch, train_loss, train_acc, valid_loss,
                           valid_acc])
        print('Epoch: {} \tTraining Loss: {: .4f} \tTraining Accuracy: {: .4f}\
              \tValidation Loss: {: .4f} \tValidation Accuracy: {: .4f}\
              '.format(epoch, train_loss, train_acc, valid_loss, valid_acc))

        if stp == 2:
            # print('Using early stopping')
            if earlyStopping(early_stop, valid_acc, epoch,
                             cfg["model"]["sens"]) == 1:
                break
        elif stp == 3:
            # print('Using energy bound')
            if energyBound(cfg["model"]["energy_thrs"]) == 1:
                break
        elif stp == 4:
            # print('Using accuracy bound')
            if accuracyBound(train_acc,
                             cfg["model"]["acc_thrs"]) == 1:
                break
        else:
            print('Training for {} epochs'.format(cfg["model"]["n_epochs"]))

        if sav == 1:
            # save model when finished
            # if epoch == n_epochs:
            #     torch.save(net.state_dict(), ckpt_name)
            torch.save({
                'epoch': epoch,
                'model_state_dict': net.state_dict(),
                'optimizer_state_dict': optimizer.state_dict(),
                'loss': train_loss,
                }, ckpt_name + '_epoch_{}.pt'.format(epoch))

#    with open("freq_exp_data_"+str(cfg["model"]["size"])+".pkl", 'wb') as f:
#        pickle.dump(train_data, f)


if __name__ == '__main__':
    now = datetime.now()
    current_time = now.strftime("%H:%M:%S")
    print("Initial Time =", current_time)
    print("Using frequentist model of size: {}".format(cfg["model"]["size"]))
    run(cfg["data"], cfg["model"]["net_type"])
    now = datetime.now()
    current_time = now.strftime("%H:%M:%S")
    print("Final Time =", current_time)