#!/usr/bin/env python3

import configparser
import argparse
import subprocess
import os
import time

upath=None

def read_values(output: str):
    remaining = False
    lines = [line.strip() for line in output.split("\n")]
    for line in lines:
        if line.startswith("time to"):
            remaining = line.split(":")[-1].strip()
        elif line.startswith("percentage"):
            percentage = float(line.split(":")[-1].strip()[:-1])
        elif line.startswith("state"):
            charging = not "discharging" in line
    return percentage, charging, remaining

def write_values(percentage: float, charging: bool, remaining: str, datafile: os.PathLike):
    config = configparser.ConfigParser()
    config["BATTERY"] = {
        "percentage": percentage,
        "charging": charging,
        "remaining": remaining
    }

    with open(datafile, "w") as outfile:
        config.write(outfile)

def run_upower(path=None):
    global upath
    if not (path or upath):
        finder = subprocess.Popen(["upower", "-e"], stdout=subprocess.PIPE)
        finder.wait()
        for line in finder.stdout.read().decode().split("\n"):
            if "BAT" in line:
                upath = line
                break

    path = path or upath

    info = subprocess.Popen(["upower", "-i", path], stdout=subprocess.PIPE)
    info.wait()
    return info.stdout.read().decode()

def run_loop(datafile):
    while True:
        write_values(*read_values(run_upower()), datafile)
        time.sleep(1)

if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument("datafile")
    args = parser.parse_args()
    run_loop(args.datafile)