#!/usr/bin/env python3

import sys
import re
from sys import stdout
from os import path, environ
from os.path import join, isdir
from collections import namedtuple, OrderedDict


POWER_CLASS = '/sys/class/power_supply'
BATTERIES = (
	environ.get('BATTERY', 'BAT0'),
	'cw2015-battery'
)
DISCHARNGING = 'Discharging'

RESET = '0'
RED = '0;31'
GREEN = '0;32'
YELLOW = '0;33'
BLUE = '0;34'
MAGENTA = '0;35'
CYAN = '0;36'


BatteryInfo = namedtuple(
	'BatteryInfo',
	[
		'name',
        'model',
        'manufacturer',
		'technology',
		'capacity',
		'status',
		'currrent_percent',
		'time_to_empty',
		'charging_current'
	]
)


def print_help():
	text = """
		battery [-h] [-d] [-i]
		-h ... help
		-d ... dump all values
		-i ... short info
	""".strip()
	pattern = re.compile(r'^\s+', re.MULTILINE)
	text = pattern.sub('', text)
	print(text)


def find_battery_uevent(batteries):
	for battery in batteries:
		path = join(POWER_CLASS, battery)
		if isdir(path):
			return join(path, 'uevent')
	return None


def start_color(color):
	return '\033[' + color + 'm'


def colored(text, color):
	return start_color(color) + text + start_color(RESET)


def read_battery(filename):
	with open(filename) as file:
		lines = file.readlines()
		items = map(lambda line: line.strip().split('=', 2), lines)
		return OrderedDict(items)


def load_battery_info(info):
	return BatteryInfo(
		name = info['POWER_SUPPLY_NAME'],
        model = info.get('POWER_SUPPLY_MODEL_NAME', ''),
        manufacturer = info.get('POWER_SUPPLY_MANUFACTURER', ''),
		technology = info['POWER_SUPPLY_TECHNOLOGY'],
		capacity = float(info['POWER_SUPPLY_CHARGE_FULL']) / 1e6,
		status = info['POWER_SUPPLY_STATUS'],
		currrent_percent = int(info['POWER_SUPPLY_CAPACITY']),
		time_to_empty = int(info.get('POWER_SUPPLY_TIME_TO_EMPTY_NOW', 0)),
		charging_current = int(float(info['POWER_SUPPLY_CURRENT_NOW']) / 1e3)
	)


def terminal_colored(text, color):
	if sys.stdout.isatty():
		return colored(text, color)
	else:
		return text


def format_status(info):
	color = RED if info.status == DISCHARNGING else GREEN
	return terminal_colored(info.status, color)


def format_percent(info):
	color = GREEN if info.currrent_percent > 30 else RED
	return terminal_colored(f'{info.currrent_percent}%', color)


def format_time_to_empty(info):
	if info.time_to_empty == 0:
		return '??:??'
	else:
		hours = info.time_to_empty // 60
		minutes = info.time_to_empty % 60
		return terminal_colored(f"{hours}:{minutes:02d}", CYAN)


def battery_model(info):
	model = ''
	if info.model:
		model += info.model
	if info.manufacturer:
		if model:
			model += ' - '
		model += info.manufacturer
	if model:
		model += ': '
	return model


def print_battery_detail(info):
	model = battery_model(info)
	capacity = terminal_colored(str(info.capacity), YELLOW)
	print(f"Battery: {model}{info.technology} {capacity} Ah")
	print("Battery level: " + format_percent(info))
	print("Battery status: " + format_status(info))
	if info.status == DISCHARNGING:
		time_to_empty = format_time_to_empty(info)
		print(f"Time to empty: {time_to_empty} [hour:minutes]")
		print(f"{info.status} current: {info.charging_current} mA")


def print_battery_info(info):
	percent = format_percent(info)
	status = format_status(info)
	state = f"level={percent} status={status}"
	if info.status == DISCHARNGING:
		time_to_empty = format_time_to_empty(info)
		state += f" duration={time_to_empty}"
	print(state)


def dump_battery_info(uevent, battery):
	print(f"# {uevent}")
	for key, value in battery.items():
		print(f"{key} = {value}")


def main(args):
	uevent = find_battery_uevent(BATTERIES)
	if not uevent:
		print("No battery found")
		return
	battery = read_battery(uevent)
	info = load_battery_info(battery)
	if '-h' in args:
		print_help()
	elif '-d' in args:
		dump_battery_info(uevent, battery)
	elif '-i' in args:
		print_battery_info(info)
	else:
		print_battery_detail(info)


if __name__ == '__main__':
	main(sys.argv)


"""
cat /sys/class/power_supply/cw2015-battery/uevent
POWER_SUPPLY_NAME=cw2015-battery
POWER_SUPPLY_TYPE=Battery
POWER_SUPPLY_CAPACITY=100
POWER_SUPPLY_STATUS=Full
POWER_SUPPLY_PRESENT=1
POWER_SUPPLY_VOLTAGE_NOW=4314000
POWER_SUPPLY_TIME_TO_EMPTY_NOW=0
POWER_SUPPLY_TECHNOLOGY=Li-ion
POWER_SUPPLY_CHARGE_FULL=9800000
POWER_SUPPLY_CHARGE_FULL_DESIGN=9800000
POWER_SUPPLY_CURRENT_NOW=0
"""