bt_power.py

#!/usr/bin/env python3
""" Show bluetooth power for named device on macOS
"""

import sys
import json
from subprocess import check_output, DEVNULL
from argparse import ArgumentParser, RawDescriptionHelpFormatter


def get_profile_dt(data_type):
    output = check_output(['system_profiler', data_type, '-json'],
                          encoding=sys.getdefaultencoding(),
                          stderr=DEVNULL)
    jdict = json.loads(output)
    return jdict.pop(data_type)


def get_devices(dt_profiles):
    devices = {}
    for dt_p in dt_profiles:
        for d in dt_p['device_title']:
            for key in d:
                if key in devices:
                    raise RuntimeError(f'Duplicate device name {key}')
                devices[key] = d[key]
    return devices


def get_device(devices, device_name):
    found = [d for d in devices if list(d) == [device_name]]
    if not found:
        dev_names = sum([list(d) for d in devices], [])
        raise RuntimeError(f'Could not find device "{device_name}"\n'
                           'Options are:\n' + '; '.join(dev_names))
    if len(found) > 1:
        raise RuntimeError(f'More than one device "{device_name}"')


def extract_attr(devices, device_name, attr='device_RSSI'):
    device = devices.get(device_name)
    if device_name is None:
        raise RuntimeError(f'Could not find device "{device_name}"\n'
                           'Options are:\n' + '; '.join(devices))
    connected = device.get('device_isconnected')
    if connected is None:
        raise RuntimeError(f'No connection information for "{device_name}"')
    if connected == 'attrib_No':
        raise RuntimeError(f'Device "{device_name}" not connected')
    data = device.get(attr)
    if data is None:
        raise RuntimeError(f'No attribute "{attr}" for "{device_name}"')
    return data


def get_parser():
    parser = ArgumentParser(description=__doc__,  # Usage from docstring
                            formatter_class=RawDescriptionHelpFormatter)
    parser.add_argument('bt_device_name', nargs='?',
                        help='Bluetooth device name')
    return parser


def main():
    parser = get_parser()
    args = parser.parse_args()
    bt_p = get_profile_dt('SPBluetoothDataType')
    devices = get_devices(bt_p)
    if args.bt_device_name is None:
        print('Specify device name.  One of:\n' +
              '; '.join(get_devices(bt_p)), file=sys.stderr)
        return(1)
    print(extract_attr(devices, args.bt_device_name, 'device_RSSI'))


if __name__ == '__main__':
    main()