import os
import torch
import pickle
import random
from options import config, states
from torch.nn import functional as F
from torch.nn import L1Loss
import matchzoo as mz
import numpy as np
from fast_adapt import fast_adapt


def test(embedding,head, total_dataset, batch_size, num_epoch):

    test_set_size = len(total_dataset)
    random.shuffle(total_dataset)
    a, b, c, d = zip(*total_dataset)
    losses_q = []
    ndcgs1 = []
    ndcgs3 = []

    for iterator in range(test_set_size):
        if config['use_cuda']:
            try:
                supp_xs = a[iterator].cuda()
                supp_ys = b[iterator].cuda()
                query_xs = c[iterator].cuda()
                query_ys = d[iterator].cuda()
            except IndexError:
                print("index error in test method")
                continue
        else:
            try:
                supp_xs = a[iterator]
                supp_ys = b[iterator]
                query_xs = c[iterator]
                query_ys = d[iterator]
            except IndexError:
                print("index error in test method")
                continue

        num_local_update = config['inner']
        learner = head.clone()
        temp_sxs = embedding(supp_xs)
        temp_qxs = embedding(query_xs)

        evaluation_error,predictions = fast_adapt(learner,
                                      temp_sxs,
                                      temp_qxs,
                                      supp_ys,
                                      query_ys,
                                      config['inner'],
                                      get_predictions=True
                                      )

        l1 = L1Loss(reduction='mean')
        loss_q = l1(predictions.view(-1), query_ys)
        # print("testing - iterator:{} - l1:{} ".format(iterator,loss_q))
        losses_q.append(float(loss_q))

        y_true = query_ys.cpu().detach().numpy()
        y_pred = predictions.cpu().detach().numpy()
        ndcgs1.append(float(mz.metrics.NormalizedDiscountedCumulativeGain(k=1)(y_true, y_pred)))
        ndcgs3.append(float(mz.metrics.NormalizedDiscountedCumulativeGain(k=3)(y_true, y_pred)))

        del supp_xs, supp_ys, query_xs, query_ys, predictions, y_true, y_pred, loss_q
        # torch.cuda.empty_cache()

    # calculate metrics
    # losses_q = torch.stack(losses_q).mean(0)
    losses_q = np.array(losses_q).mean()
    print("mean of mse: ", losses_q)
    n1 = np.array(ndcgs1).mean()
    print("nDCG1: ", n1)
    n3 = np.array(ndcgs3).mean()
    print("nDCG3: ", n3)