"""
Parse the operator's Linux identity from /etc/passwd and the environment.

GECOS format: "Full Name,Room Number,Work Phone,Home Phone,Other"
We only need the first field (full name).
"""

import os
import pwd


def current_username() -> str:
    """Return the current Linux username."""
    return (
        os.environ.get("USER")
        or os.environ.get("LOGNAME")
        or pwd.getpwuid(os.getuid()).pw_name
    )


def get_gecos_fullname(username: str) -> str:
    """
    Extract the full name from /etc/passwd GECOS for the given username.
    Falls back to the username itself if GECOS is absent or unparseable.
    """
    try:
        entry = pwd.getpwnam(username)
        # GECOS may be "Full Name,room,work,home,other" — take the first field
        fullname = entry.pw_gecos.split(",")[0].strip()
        if fullname:
            return fullname
    except KeyError:
        pass
    return username