import re
from typing import Dict, List, Union


def product_data_to_str(product_data: Dict[str, Union[str, List[str]]]) -> str:
    """
    Convert product data to a string.

    Args:
    - product_data: a dictionary of product data

    Returns:
    - a string representation of the product data
    """
    if product_data is None:
        return ""

    data_list = []
    for k, v in product_data.items():
        data_line = None
        if isinstance(v, list):
            delimiter = ","
            for sub_v in v:
                if "," in sub_v:
                    delimiter = (
                        ";"  # Use semicolon as delimiter if comma is found in the value
                    )

            for i, sub_v in enumerate(v):
                if ";" in sub_v:
                    v[i] = f'"{sub_v}"'

            data_line = f"{k}: {f'{delimiter} '.join(v)}"
        elif isinstance(v, str):
            data_line = f"{k}: {v}"
        else:
            raise ValueError(
                f"Unsupported data type for value of product data: {type(v)}. Only list and str are supported."
            )

        data_list.append(data_line)

    return "\n".join(data_list)


def to_snake_case(s):
    # Remove leading/trailing whitespace and convert to lowercase
    s = s.strip().lower()
    # Replace spaces, hyphens, and periods with underscores
    s = re.sub(r'[\s\-\.\+]', '_', s)
    # Remove any characters that are not alphanumeric or underscores
    s = re.sub(r'[^a-z0-9_]', '', s)
    # Replace multiple underscores with a single one
    s = re.sub(r'_+', '_', s)
    # Remove leading digits (Python variable names can't start with a number)
    s = re.sub(r'^[0-9]+', '', s)
    # Make sure it doesn't start with an underscore and is not empty
    if not s or not s[0].isalpha():
        s = 'var_' + s
    return s