# copyright (c) 2024 PaddlePaddle Authors. All Rights Reserve.
#
# 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.

import os
import ast
from pathlib import Path
import numpy as np
import pandas as pd

from ....utils import logging
from ....utils.download import download
from ....utils.cache import CACHE_DIR
from .base_batch_sampler import BaseBatchSampler


class TSBatchSampler(BaseBatchSampler):
    """Batch sampler for time series data, supporting CSV file inputs."""

    SUFFIX = ["csv"]

    def _download_from_url(self, in_path: str) -> str:
        """Download a file from a URL to a cache directory.

        Args:
            in_path (str): URL of the file to be downloaded.

        Returns:
            str: Path to the downloaded file.
        """
        file_name = Path(in_path).name
        save_path = Path(CACHE_DIR) / "predict_input" / file_name
        download(in_path, save_path, overwrite=True)
        return save_path.as_posix()

    def _get_files_list(self, fp: str) -> list:
        """Get a list of CSV files from a directory or a single file path.

        Args:
            fp (str): Path to a directory or a single CSV file.

        Returns:
            list: Sorted list of CSV file paths.

        Raises:
            Exception: If no CSV file is found in the path.
        """
        file_list = []
        if fp is None or not os.path.exists(fp):
            raise Exception(f"Not found any csv file in path: {fp}")

        if os.path.isfile(fp) and fp.split(".")[-1] in self.SUFFIX:
            file_list.append(fp)
        elif os.path.isdir(fp):
            for root, dirs, files in os.walk(fp):
                for single_file in files:
                    if single_file.split(".")[-1] in self.SUFFIX:
                        file_list.append(os.path.join(root, single_file))
        if len(file_list) == 0:
            raise Exception("Not found any file in {}".format(fp))
        file_list = sorted(file_list)
        return file_list

    def sample(self, inputs: list) -> list:
        """Generate batches of data from inputs, which can be DataFrames or file paths.

        Args:
            inputs (list): List of DataFrames or file paths.

        Yields:
            list: A batch of data which is either DataFrames or file paths.
        """
        if not isinstance(inputs, list):
            inputs = [inputs]

        batch = []
        for input in inputs:
            if isinstance(input, pd.DataFrame):
                batch.append(input)
                if len(batch) == self.batch_size:
                    yield batch
                    batch = []
            elif isinstance(input, str):
                file_path = (
                    self._download_from_url(input)
                    if input.startswith("http")
                    else input
                )
                file_list = self._get_files_list(file_path)
                for file_path in file_list:
                    batch.append(file_path)
                    if len(batch) == self.batch_size:
                        yield batch
                        batch = []
            else:
                logging.warning(
                    f"Not supported input data type! Only `pd.DataFrame` and `str` are supported! So has been ignored: {input}."
                )
        if len(batch) > 0:
            yield batch