#!/usr/bin/env python3

from __future__ import absolute_import, division, print_function

import argparse
import os
import os.path
import subprocess
import sys
import time


def eprint(*args, **kwargs):
    kwargs['file'] = sys.stderr
    print(*args, **kwargs)


def bat_value(fname):
    f = os.path.join(batdir, fname)
    if not os.access(f, os.R_OK):
        eprint('Could not access "%s".' % f)
        sys.exit(1)
    val = 0.0
    try:
        val = abs(float(open(f).read()))
    except IOError:
        eprint('Could not open "%s".' % f)
        sys.exit(1)
    except ValueError:
        eprint(
            'The value "%s", returned from "%s", is not a valid float.'
            % (open(f).read(), f))
    return val


def output():
    full, now, pow_now = bat_value(ffull), bat_value(fnow), bat_value(fpow_now)

    charged = '%d' % (100 * (now / full))

    # If the battery isn't discharging, just report 'AC' instead of
    # the time remaining. We also consider it on A/C when the charge is
    # a very high percentage of a full charge. This is because it appears
    # that sometimes the status is 'Discharging' even when plugged into
    # AC. (For Framework laptop.)
    status = open(os.path.join(batdir, 'status')).read().strip()
    if status != 'Discharging' or (now / full) > 0.995:
        print('%s%% AC' % charged)
        sys.stdout.flush()
        return

    seconds_rem = (now * 60 * 60) / pow_now
    minutes_rem = '%d' % ((seconds_rem / 60) % 60)
    hours_rem = '%d' % (seconds_rem / 60 / 60)

    def rem():
        if conf.short_rem:
            return '%hh%mm'
        return '%h hours, %m minutes'

    format_str = ''
    if conf.format_str:
        format_str = conf.format_str
    elif conf.output_type == 'charge':
        format_str = '%c%'
    elif conf.output_type == 'rem':
        format_str = rem()
    else:
        format_str = rem() + ' %c%'
    assert(len(format_str) > 0)

    out = format_str
    out = out.replace('%c', charged)
    out = out.replace('%h', hours_rem)
    out = out.replace('%m', minutes_rem)
    print(out)
    sys.stdout.flush()


if __name__ == '__main__':
    parser = argparse.ArgumentParser(
        description='Emit battery status charge level and time remaining.',
        formatter_class=argparse.ArgumentDefaultsHelpFormatter)
    aa = parser.add_argument
    aa('-f', '--format-str', type=str, metavar='FORMAT_STRING',
       help='A format string overrides the "-s" and "-t" options, and allows '
            'complete control over the formatting of the battery status '
            'message. Use "%%h" for hours, "%%m" for minutes and "%%c" for '
            'charge level. For example, using '
            '"%%h hours, %%m minutes (%%c%%)" a sample output '
            'might look like "5 hours, 16 minutes (66.90%%)".')
    aa('-i', '--interval', type=int, metavar='POLL_INTERVAL_SECONDS',
       help='The time, in seconds, between battery status polling. If this '
            'option is not specified, the current battery status will be '
            'printed once, and the program will exit.')
    aa('-s', '--short-rem', action='store_true',
       help='When enabled, the "time remaining" display will be shortened '
            'form "X hours, Y minutes" to "XhYm".')
    aa('-t', '--output-type', choices=['charge', 'rem'], metavar='OUTPUT_TYPE',
       help='The type of output to display. If this option is omitted, both '
            'the charge level and the time remaining are displayed. If '
            '"charge" is specified, only the charge level is displayed. If '
            '"rem" is specified, only the time remaining is displayed.')
    conf = parser.parse_args()

    host = subprocess.check_output(['myhostname']).decode('utf-8').strip()
    batdir = ''
    ffull = 'energy_full'
    fnow = 'energy_now'
    fpow_now = 'power_now'

    batdir = subprocess.check_output(['batpath']).decode('utf-8').strip()
    if host in ('maggie', 'bart'):
        ffull = 'charge_full'
        fnow = 'charge_now'
        fpow_now = 'current_now'

    if not os.path.isdir(batdir):
        eprint('Battery directory "%s" is not accessible.' % batdir)
        sys.exit(1)

    if conf.interval is not None and conf.interval > 0:
        while True:
            output()
            time.sleep(conf.interval)
    else:
        output()