import torch
import pickle
from options import config
import random


def cl_loss(c):
    alpha = config['alpha']
    beta = config['beta']
    d = config['d']
    a = torch.div(1, torch.add(1, torch.exp(torch.mul(-1, torch.mul(alpha, torch.sub(torch.mul(d, c), beta))))))
    # a = 1 / (1 + torch.exp((-1) * alpha * (d * c - beta)))
    b = torch.mul(a, torch.mul(torch.sub(1, a), torch.sub(1, torch.mul(2, a))))
    # b = 1 * a * (1 - a) * (1 - 2 * a)
    loss = torch.sum(b)
    return loss


def fast_adapt(
        learn,
        adaptation_data,
        evaluation_data,
        adaptation_labels,
        evaluation_labels,
        adaptation_steps,
        get_predictions=False,
        epoch=None):
    for step in range(adaptation_steps):
        temp, c = learn(adaptation_data, adaptation_labels, training=True)
        train_error = torch.nn.functional.mse_loss(temp.view(-1), adaptation_labels)
        cluster_loss = cl_loss(c)
        total_loss = train_error + config['cluster_loss_weight'] * cluster_loss
        learn.adapt(total_loss)

    predictions, c = learn(evaluation_data, None, training=False, adaptation_data=adaptation_data,
                           adaptation_labels=adaptation_labels)
    valid_error = torch.nn.functional.mse_loss(predictions.view(-1), evaluation_labels)
    cluster_loss = cl_loss(c)
    total_loss = valid_error + config['cluster_loss_weight'] * cluster_loss

    if random.random() < 0.05:
        print("cl:", round(cluster_loss.item()), "\t c:", c[0].cpu().data.numpy())

    if get_predictions:
        return total_loss, predictions
    return total_loss