get status from wpa_ctl interface

"""
Source: https://stackoverflow.com/questions/60422924/writing-an-external-program-to-interface-with-wpa-supplicant

Commands: https://w1.fi/wpa_supplicant/devel/ctrl_iface_page.html
"""

import json
import os
import time
from contextlib import contextmanager
from socket import AF_UNIX, SOCK_DGRAM, socket


@contextmanager
def connect():
    req_sock = socket(AF_UNIX, SOCK_DGRAM)
    rep_sock = socket(AF_UNIX, SOCK_DGRAM)

    req_sock_file = "/run/wpa_supplicant/wlan0"
    rep_sock_file = "/run/wpa_supplicant/reply"

    if not os.path.exists(req_sock_file):
        raise SystemExit("wpa_supplicant unix socket does not exist.")

    req_sock.connect(req_sock_file)
    rep_sock.bind(rep_sock_file)
    rep_sock.settimeout(1)

    yield rep_sock, req_sock_file

    req_sock.close()
    rep_sock.close()

    os.unlink(rep_sock_file)


def parse(raw_bytes):
    text = raw_bytes.decode()
    result = {}
    for line in text.splitlines():
        key, value = line.strip().split("=", maxsplit=1)
        result[key] = value

    return result


def main():
    with connect() as (sock, file):
        sock.sendto(b"STATUS", file)

        data = sock.recv(4096)
        result = parse(data)
        print(json.dumps(result))


if __name__ == "__main__":
    main()