# 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.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()
