# This test is meant to be run in on an instance with TPUs like this:
#
#   python examples/xla_spawn.py --num_cores=8 tests/test_trainer_tpu.py
#
# Replace 8 with the number of TPU cores you have.
#

import sys
from typing import Dict

from transformers import EvalPrediction, HfArgumentParser, TrainingArguments, is_torch_available
from transformers.utils import logging


logger = logging.get_logger(__name__)


if is_torch_available():
    import torch
    from torch import nn
    from torch.utils.data.dataset import Dataset

    from transformers import Trainer

    class DummyDataset(Dataset):
        def __init__(self, length: int = 101):
            self.length = length

        def __len__(self):
            return self.length

        def __getitem__(self, i) -> int:
            return i

    class DummyDataCollator:
        def __call__(self, features):
            return {"input_ids": torch.tensor(features), "labels": torch.tensor(features)}

    class DummyModel(nn.Module):
        def __init__(self):
            super().__init__()
            # Add some (unused) params otherwise DDP will complain.
            self.fc = nn.Linear(120, 80)

        def forward(self, input_ids, labels=None):
            if labels is not None:
                return torch.tensor(0.0, device=input_ids.device), input_ids
            else:
                return input_ids


def main():
    parser = HfArgumentParser((TrainingArguments,))
    sys.argv += ["--output_dir", "./examples"]
    training_args = parser.parse_args_into_dataclasses()[0]

    logger.warning(
        "Process rank: %s, device: %s, tpu_num_cores: %s",
        training_args.local_rank,
        training_args.device,
        training_args.tpu_num_cores,
    )

    # Essentially, what we want to verify in the distributed case is
    # that we get all samples back, in the right order.
    # (this is crucial for prediction for instance)
    for dataset_length in [1001, 256, 15]:
        dataset = DummyDataset(dataset_length)

        def compute_metrics(p: EvalPrediction) -> Dict:
            sequential = list(range(len(dataset)))
            success = p.predictions.tolist() == sequential and p.label_ids.tolist() == sequential
            return {"success": success}

        trainer = Trainer(
            model=DummyModel(),
            args=training_args,
            data_collator=DummyDataCollator(),
            eval_dataset=dataset,
            compute_metrics=compute_metrics,
        )
        metrics = trainer.evaluate()
        logger.info(metrics)
        if metrics["eval_success"] is not True:
            logger.error(metrics)
            exit(1)

        p = trainer.predict(dataset)
        logger.info(p.metrics)
        if p.metrics["eval_success"] is not True:
            logger.error(p.metrics)
            exit(1)

        trainer.args.eval_accumulation_steps = 2

        metrics = trainer.evaluate()
        logger.info(metrics)
        if metrics["eval_success"] is not True:
            logger.error(metrics)
            exit(1)

        p = trainer.predict(dataset)
        logger.info(p.metrics)
        if p.metrics["eval_success"] is not True:
            logger.error(p.metrics)
            exit(1)

        trainer.args.eval_accumulation_steps = None

    logger.info("🔥 All distributed tests successful")


def _mp_fn(index):
    # For xla_spawn (TPUs)
    main()


if __name__ == "__main__":
    main()
