rssi.py

#!/usr/bin/env python3
"""
Use the MacOS `airport` utility to get a running average of the WiFi signal
strength (RSSI).

Python 3.8+, so works with `/usr/bin/python3` on Monterey.
"""

import os
import statistics
import subprocess
import typing as t
from argparse import ArgumentParser
from collections import deque
from pathlib import Path


def airport():
    path = (
        Path(Path().absolute().anchor)
        / "System"
        / "Library"
        / "PrivateFrameworks"
        / "Apple80211.framework"
        / "Versions"
        / "Current"
        / "Resources"
    )
    env = {"PATH": str(path)}

    result = subprocess.run(
        "airport --getinfo".split(),
        env=env,
        capture_output=True,
    )
    parts: t.Dict[str, str | int | None] = {
        next(items): next(items, None)
        for line in result.stdout.decode().splitlines()
        if (items := (item.strip() for item in line.split(": ")))
    }

    for k, v in parts.items():
        if v is None:
            continue
        try:
            # If it looks identical to an int, make it an int
            newv = int(v)
            if str(newv) == v:
                parts[k] = newv
        except ValueError:
            pass
    return parts


def get_rssi(wifi: dict):
    return wifi.get("agrCtlRSSI")


def cli():
    parser = ArgumentParser()
    n_default = 500
    n_help = (
        "Number of values to include in running average. 0 means "
        f"inifinite. Default is {n_default}"
    )
    parser.add_argument(
        "-n",
        "--num-running",
        type=int,
        help=n_help,
        default=n_default,
    )
    return parser.parse_args()


def main():
    args = cli()

    maxlen = args.num_running
    if maxlen == 0:
        maxlen = None

    vals = deque(maxlen=maxlen)
    while True:
        wifi = airport()
        rssi = get_rssi(wifi)

        # I think it will have a value on every call, but JIC
        if rssi is None:
            continue

        if len(vals) == vals.maxlen:
            vals.popleft()
        vals.append(rssi)

        os.system("clear")
        mean = statistics.mean(vals)
        print(f"{mean:.2f}")


if __name__ == "__main__":
    main()