import os
from dataclasses import dataclass, field
from typing import Literal, Optional

from datasets import DownloadMode


@dataclass
class EvaluationArguments:
    r"""
    Arguments pertaining to specify the evaluation parameters.
    """
    task: str = field(metadata={"help": "Name of the evaluation task."})
    task_dir: Optional[str] = field(
        default="evaluation", metadata={"help": "Path to the folder containing the evaluation datasets."}
    )
    batch_size: Optional[int] = field(default=4, metadata={"help": "The batch size per GPU for evaluation."})
    seed: Optional[int] = field(default=42, metadata={"help": "Random seed to be used with data loaders."})
    lang: Optional[Literal["en", "zh"]] = field(default="en", metadata={"help": "Language used at evaluation."})
    n_shot: Optional[int] = field(default=5, metadata={"help": "Number of examplars for few-shot learning."})
    save_dir: Optional[str] = field(default=None, metadata={"help": "Path to save the evaluation results."})
    download_mode: Optional[DownloadMode] = field(
        default=DownloadMode.REUSE_DATASET_IF_EXISTS,
        metadata={"help": "Download mode used for the evaluation datasets."},
    )

    def __post_init__(self):
        if self.save_dir is not None and os.path.exists(self.save_dir):
            raise ValueError("`save_dir` already exists, use another one.")