# Copyright (c) MONAI Consortium
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#     http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import annotations

import unittest

import numpy as np
import torch
import torch.distributed as dist

from monai.handlers import ROCAUC
from monai.transforms import Activations, AsDiscrete
from tests.test_utils import DistCall, DistTestCase


class DistributedROCAUC(DistTestCase):
    @DistCall(nnodes=1, nproc_per_node=2, node_rank=0)
    def test_compute(self):
        auc_metric = ROCAUC()
        act = Activations(softmax=True)
        to_onehot = AsDiscrete(to_onehot=2)

        device = f"cuda:{dist.get_rank()}" if torch.cuda.is_available() else "cpu"
        if dist.get_rank() == 0:
            y_pred = [torch.tensor([0.1, 0.9], device=device), torch.tensor([0.3, 1.4], device=device)]
            y = [torch.tensor([0], device=device), torch.tensor([1], device=device)]

        if dist.get_rank() == 1:
            y_pred = [
                torch.tensor([0.2, 0.1], device=device),
                torch.tensor([0.1, 0.5], device=device),
                torch.tensor([0.3, 0.4], device=device),
            ]
            y = [torch.tensor([0], device=device), torch.tensor([1], device=device), torch.tensor([1], device=device)]

        y_pred = [act(p) for p in y_pred]
        y = [to_onehot(y_) for y_ in y]
        auc_metric.update([y_pred, y])

        result = auc_metric.compute()
        np.testing.assert_allclose(0.66667, result, rtol=1e-4)


if __name__ == "__main__":
    unittest.main()
