"""Utility functions for switchbot."""

from collections.abc import Mapping
from functools import lru_cache

_REQUEST_ID_HEADERS = ("x-request-id", "x-amzn-requestid", "cf-ray")


def extract_request_id(headers: Mapping[str, str]) -> str | None:
    """Extract a provider request identifier for log correlation."""
    normalized_headers = {name.lower(): value for name, value in headers.items()}
    return next(
        (
            value
            for name in _REQUEST_ID_HEADERS
            if (value := normalized_headers.get(name))
        ),
        None,
    )


@lru_cache(maxsize=512)
def format_mac_upper(mac: str) -> str:
    """Format the mac address string to uppercase with colons."""
    to_test = mac

    if len(to_test) == 17 and to_test.count(":") == 5:
        return to_test.upper()

    if len(to_test) == 17 and to_test.count("-") == 5:
        to_test = to_test.replace("-", "")
    elif len(to_test) == 14 and to_test.count(".") == 2:
        to_test = to_test.replace(".", "")

    if len(to_test) == 12:
        # bare 12-char hex, insert colons
        return ":".join(to_test.upper()[i : i + 2] for i in range(0, 12, 2))

    # Not sure how formatted, return original
    return mac.upper()