"""
Generic utility functions for the app.
"""

from typing import Any


def lowercase_keys(data: dict | list) -> Any:
    """Recursively lowercases the keys of a dictionary or list of dictionaries.

    Args:
        data (dict or list): The input data, which can be a dictionary or a
         list of dictionaries.
        If it's a list, all dictionaries in the list will have their keys lowercased.
        If it's a dictionary, its keys will be lowercased.

    Returns:
        dict or list: The input data with all keys lowercased.

    Raises:
        TypeError: If the input data is neither a dictionary nor a list of dictionaries.
    """
    if isinstance(data, list):
        return [lowercase_keys(item) for item in data]
    elif isinstance(data, dict):
        return {k.lower(): lowercase_keys(v) for k, v in data.items()}
    # If the data is neither a dictionary nor a list, return it as is,
    # to stop recursion.
    return data