"""Helpers shared by the parsers: WS-Management values are strings, lists or missing."""

from __future__ import annotations

from typing import Any

#: Values firmware puts where it has nothing to say (SMBIOS defaults), compared lowercased.
PLACEHOLDERS = frozenset(
    {
        "",
        "0",
        "none",
        "default string",
        "not specified",
        "to be filled by o.e.m.",
        "system product name",
        "system serial number",
        "123456789",
    }
)


def as_list(value: Any) -> list[Any]:
    """A repeated element as a list; a single one as a list of one; none as empty."""
    if value is None or value == "":
        return []
    return value if isinstance(value, list) else [value]


def first(value: Any) -> Any:
    """The first of a value that may be repeated."""
    values = as_list(value)
    return values[0] if values else None


def to_int(value: Any) -> int | None:
    try:
        return int(str(first(value)).strip())
    except (TypeError, ValueError):
        return None


def is_true(value: Any) -> bool:
    return str(first(value)).strip().lower() in ("true", "1")


def text(value: Any) -> str:
    """A string value, stripped; a missing or nested one as empty."""
    value = first(value)
    return value.strip() if isinstance(value, str) else ""


def meaningful(value: Any) -> str:
    """``text(value)``, or empty for a firmware placeholder."""
    result = text(value)
    return "" if result.lower() in PLACEHOLDERS else result