"""
Parses and extracts the company based on the MAC address.

"""

import functools
import os


# Maps the first 3 (or more) bytes of the MAC address to the company name.
_oui_dict = {}

_oui_length_split_list = []


@functools.lru_cache(maxsize=1)
def parse_wireshark_oui_database() -> None:
    _oui_length_splits = set()

    wireshark_oui_db_file_path = os.path.join(
        os.path.dirname(os.path.realpath(__file__)),
        "..",
        "data",
        "wireshark_oui_database.txt",
    )
    with open(wireshark_oui_db_file_path, encoding="utf-8") as fp:
        for line in fp:
            line = line.strip()
            if line == "" or line.startswith("#"):
                continue
            (oui, _, company) = line.split("\t")
            oui = oui.split("/", 1)[0].lower().replace(":", "").strip()
            _oui_dict[oui] = company.strip()
            _oui_length_splits.add(len(oui))

    _oui_length_split_list.extend(sorted(_oui_length_splits))


@functools.lru_cache(maxsize=1024)
def get_vendor(mac_addr: str) -> str:
    """Given a MAC address, returns the vendor. Returns '' if unknown."""

    parse_wireshark_oui_database()

    mac_addr = mac_addr.lower().replace(":", "").replace("-", "").replace(".", "")

    # Split the MAC address in different ways and check against the oui_dict
    for split_length in _oui_length_split_list:
        oui = mac_addr[:split_length]
        if oui in _oui_dict:
            return _oui_dict[oui]

    return ""


def test() -> None:
    assert get_vendor("74:F8:DB:E0:00:00") == "Bernard Krone Holding GmbH & Co. KG"
    assert get_vendor("8C:1F:64:00:30:00") == "Brighten Controls LLP"
    assert get_vendor("8C:1E:80:00:00:00") == "Cisco Systems, Inc"


if __name__ == "__main__":
    test()