# Copyright (c) OpenMMLab. All rights reserved.
import logging
import tempfile
from unittest.mock import MagicMock

import torch
import torch.nn as nn
from mmcv.parallel import MMDataParallel
from mmcv.runner import build_runner, obj_from_dict
from torch.utils.data import DataLoader, Dataset

from mmselfsup.core.hooks import SwAVHook
from mmselfsup.models.heads import SwAVHead


class ExampleDataset(Dataset):

    def __getitem__(self, idx):
        results = dict(img=torch.tensor([1.]), img_metas=dict())
        return results

    def __len__(self):
        return 1


class ExampleModel(nn.Module):

    def __init__(self):
        super(ExampleModel, self).__init__()
        self.test_cfg = None
        self.linear = nn.Linear(1, 1)
        self.prototypes_test = nn.Linear(1, 1)
        self.head = SwAVHead(feat_dim=2, num_crops=[2, 6], num_prototypes=3)

    def forward(self, img, img_metas, test_mode=False, **kwargs):
        out = self.linear(img)
        out = self.prototypes_test(out)
        return out

    def train_step(self, data_batch, optimizer):
        loss = self.forward(**data_batch)
        return dict(loss=loss)


def test_swav_hook():
    test_dataset = ExampleDataset()
    test_dataset.evaluate = MagicMock(return_value=dict(test='success'))
    data_loader = DataLoader(
        test_dataset, batch_size=1, sampler=None, num_workers=0, shuffle=False)

    runner_cfg = dict(type='EpochBasedRunner', max_epochs=2)
    optim_cfg = dict(type='SGD', lr=0.01, momentum=0.9, weight_decay=0.0005)

    # test SwAVHook
    with tempfile.TemporaryDirectory() as tmpdir:
        model = MMDataParallel(ExampleModel())
        optimizer = obj_from_dict(optim_cfg, torch.optim,
                                  dict(params=model.parameters()))

        swav_hook = SwAVHook(
            batch_size=1,
            epoch_queue_starts=15,
            crops_for_assign=[0, 1],
            feat_dim=128,
            queue_length=300)
        runner = build_runner(
            runner_cfg,
            default_args=dict(
                model=model,
                optimizer=optimizer,
                work_dir=tmpdir,
                logger=logging.getLogger()))
        runner.register_hook(swav_hook)
        runner.run([data_loader], [('train', 1)])
        assert swav_hook.queue_length == 300
        assert runner.model.module.head.use_queue is False