"""
This module contains the base class used for evaluation.

Copyright (c) 2024 LAMDA.  All rights reserved.
"""

import logging
from abc import ABCMeta, abstractmethod
from typing import Any, List, Optional

from ...utils import print_log
from ..structures import ListData


class BaseMetric(metaclass=ABCMeta):
    """
    Base class for a metrics.

    The metrics first processes each batch of data_examples and appends the processed
    results to the results list. Then, it computes the metrics of the entire dataset.

    Parameters
    ----------
    prefix : str, optional
        The prefix that will be added in the metrics names to disambiguate homonymous
        metrics of different tasks. If prefix is not provided in the argument,
        self.default_prefix will be used instead. Defaults to None.

    """

    def __init__(
        self,
        prefix: Optional[str] = None,
    ) -> None:
        self.default_prefix = ""
        self.results: List[Any] = []
        self.prefix = prefix or self.default_prefix

    @abstractmethod
    def process(self, data_examples: ListData) -> None:
        """
        Process one batch of data examples. The processed results should be stored
        in ``self.results``, which will be used to compute the metrics when all
        batches have been processed.

        Parameters
        ----------
        data_examples : ListData
            A batch of data examples.
        """

    @abstractmethod
    def compute_metrics(self) -> dict:
        """
        Compute the metrics from processed results.

        Returns
        -------
        dict
            The computed metrics. The keys are the names of the metrics,
            and the values are the corresponding results.
        """

    def evaluate(self) -> dict:
        """
        Evaluate the model performance of the whole dataset after processing
        all batches.

        Returns
        -------
        dict
            Evaluation metrics dict on the val dataset. The keys are the
            names of the metrics, and the values are the corresponding results.
        """
        if len(self.results) == 0:
            print_log(
                f"{self.__class__.__name__} got empty `self.results`. Please "
                "ensure that the processed results are properly added into "
                "`self.results` in `process` method.",
                logger="current",
                level=logging.WARNING,
            )

        metrics = self.compute_metrics()
        # Add prefix to metrics names
        if self.prefix:
            metrics = {"/".join((self.prefix, k)): v for k, v in metrics.items()}

        # reset the results list
        self.results.clear()
        return metrics