# Copyright (c) OpenMMLab. All rights reserved.
import tempfile
from unittest import TestCase

import torch
import torch.nn as nn
from mmengine import Runner
from mmengine.data import LabelData
from mmengine.model import BaseModel as EngineBaseModel
from mmengine.model import BaseModule
from mmengine.optim import OptimWrapper
from torch.utils.data import Dataset

from mmselfsup.data import SelfSupDataSample
from mmselfsup.engine import SwAVHook
from mmselfsup.models.algorithms import BaseModel
from mmselfsup.models.heads import SwAVHead
from mmselfsup.registry import MODELS


class DummyDataset(Dataset):
    METAINFO = dict()  # type: ignore
    data = torch.randn(12, 2)
    label = torch.ones(12)

    @property
    def metainfo(self):
        return self.METAINFO

    def __len__(self):
        return self.data.size(0)

    def __getitem__(self, index):
        data_sample = SelfSupDataSample()
        gt_label = LabelData(value=self.label[index])
        setattr(data_sample, 'gt_label', gt_label)
        return dict(inputs=self.data[index], data_sample=data_sample)


@MODELS.register_module()
class SwAVDummyLayer(BaseModule):

    def __init__(self, init_cfg=None):
        super().__init__(init_cfg)
        self.linear = nn.Linear(2, 1)

    def forward(self, x):
        return self.linear(x)


class ToyModel(BaseModel):

    def __init__(self):
        super().__init__(backbone=dict(type='SwAVDummyLayer'))
        self.prototypes_test = nn.Linear(1, 1)
        self.head = SwAVHead(
            loss=dict(
                type='SwAVLoss',
                feat_dim=2,
                num_crops=[2, 6],
                num_prototypes=3))

    def loss(self, batch_inputs, data_samples):
        labels = []
        for x in data_samples:
            labels.append(x.gt_label.value)
            labels = torch.stack(labels)
        outputs = self.backbone(batch_inputs)
        loss = (labels - outputs).sum()
        outputs = dict(loss=loss)
        return outputs


class TestSwAVHook(TestCase):

    def setUp(self):
        self.temp_dir = tempfile.TemporaryDirectory()

    def tearDown(self):
        self.temp_dir.cleanup()

    def test_swav_hook(self):
        device = 'cuda:0' if torch.cuda.is_available() else 'cpu'
        dummy_dataset = DummyDataset()
        toy_model = ToyModel().to(device)
        swav_hook = SwAVHook(
            batch_size=1,
            epoch_queue_starts=15,
            crops_for_assign=[0, 1],
            feat_dim=128,
            queue_length=300,
            frozen_layers_cfg=dict(prototypes=2))

        class DummyWrapper(EngineBaseModel):

            def __init__(self, model):
                super().__init__()
                self.module = model

            def forward(self, *args, **kwargs):
                return self.module(*args, **kwargs)

        # test SwAVHook
        runner = Runner(
            model=DummyWrapper(toy_model),
            work_dir=self.temp_dir.name,
            train_dataloader=dict(
                dataset=dummy_dataset,
                sampler=dict(type='DefaultSampler', shuffle=True),
                batch_size=1,
                num_workers=0),
            optim_wrapper=OptimWrapper(
                torch.optim.Adam(toy_model.parameters())),
            param_scheduler=dict(type='MultiStepLR', milestones=[1]),
            train_cfg=dict(by_epoch=True, max_epochs=2),
            custom_hooks=[swav_hook],
            default_hooks=dict(logger=None),
            log_processor=dict(window_size=1),
            experiment_name='test_swav_hook')

        runner.train()

        for hook in runner.hooks:
            if isinstance(hook, SwAVHook):
                assert hook.queue_length == 300

        assert runner.model.module.head.loss.use_queue is False