#!/usr/bin/python3 -u
# coding=utf-8

import logging
import re
import socket
import sys
import typing

from gi.repository import GLib as glib
import signals
import config as cfg

from dbus.mainloop.glib import DBusGMainLoop
from pymodbus.client.sync import ModbusSerialClient as Modbus
from pymodbus.exceptions import ModbusException, ModbusIOException
from pymodbus.other_message import ReportSlaveIdRequest
from pymodbus.pdu import ExceptionResponse
from pymodbus.register_read_message import ReadInputRegistersResponse
from data import BatteryStatus, BatterySignal, Battery, ServiceSignal
from python_libs.ie_dbus.dbus_service import DBusService

# trick the pycharm type-checker into thinking Callable is in scope, not used at runtime
# noinspection PyUnreachableCode
if False:
	from typing import Callable, List, Iterable, NoReturn

RESET_REGISTER = 0x2087
SETTINGS_SERVICE_PREFIX = 'com.victronenergy.settings'
INVERTER_SERVICE_PREFIX = 'com.victronenergy.vebus.'



def init_modbus(tty):
	# type: (str) -> Modbus

	logging.debug('initializing Modbus')

	return Modbus(
		port='/dev/' + tty,
		method=cfg.MODE,
		baudrate=cfg.BAUD_RATE,
		stopbits=cfg.STOP_BITS,
		bytesize=cfg.BYTE_SIZE,
		timeout=cfg.TIMEOUT,
		parity=cfg.PARITY)


def init_udp_socket():
	# type: () -> socket

	s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
	s.setblocking(False)

	return s


def report_slave_id(modbus, slave_address):
	# type: (Modbus, int) -> str

	slave = str(slave_address)

	logging.debug('requesting slave id from node ' + slave)

	with modbus:

		request = ReportSlaveIdRequest(unit=slave_address)
		response = modbus.execute(request)

		if response is ExceptionResponse or issubclass(type(response), ModbusException):
			raise Exception('failed to get slave id from ' + slave + ' : ' + str(response))

		return response.identifier


def identify_battery(modbus, slave_address):
	# type: (Modbus, int) -> Battery

	logging.info('identifying battery...')

	hardware_version, bms_version, ampere_hours = parse_slave_id(modbus, slave_address)
	firmware_version = read_firmware_version(modbus, slave_address)

	specs = Battery(
		slave_address=slave_address,
		hardware_version=hardware_version,
		firmware_version=firmware_version,
		bms_version=bms_version,
		ampere_hours=ampere_hours)

	logging.info('battery identified:\n{0}'.format(str(specs)))

	return specs


def identify_batteries(modbus):
	# type: (Modbus) -> List[Battery]

	def _identify_batteries():
		slave_address = 0
		n_missing = -255

		while n_missing < 3:
			slave_address += 1
			try:
				yield identify_battery(modbus, slave_address)
				n_missing = 0
			except Exception as e:
				logging.info('failed to identify battery at {0} : {1}'.format(str(slave_address), str(e)))
				n_missing += 1

		logging.info('giving up searching for further batteries')

	batteries = list(_identify_batteries())  # dont be lazy!

	n = len(batteries)
	logging.info('found ' + str(n) + (' battery' if n == 1 else ' batteries'))

	return batteries


def parse_slave_id(modbus, slave_address):
	# type: (Modbus, int) -> (str, str, int)

	slave_id = report_slave_id(modbus, slave_address)

	sid = re.sub(r'[^\x20-\x7E]', '', slave_id)  # remove weird special chars

	match = re.match('(?P<hw>48TL(?P<ah>[0-9]+)) *(?P<bms>.*)', sid)

	if match is None:
		raise Exception('no known battery found')

	return match.group('hw').strip(), match.group('bms').strip(), int(match.group('ah').strip())


def read_firmware_version(modbus, slave_address):
	# type: (Modbus, int) -> str

	logging.debug('reading firmware version')

	with modbus:

		response = read_modbus_registers(modbus, slave_address, base_address=1054, count=1)
		register = response.registers[0]

		return '{0:0>4X}'.format(register)


def read_modbus_registers(modbus, slave_address, base_address=cfg.BASE_ADDRESS, count=cfg.NO_OF_REGISTERS):
	# type: (Modbus, int, int, int) -> ReadInputRegistersResponse

	logging.debug('requesting modbus registers {0}-{1}'.format(base_address, base_address + count))

	return modbus.read_input_registers(
		address=base_address,
		count=count,
		unit=slave_address)


def read_battery_status(modbus, battery):
	# type: (Modbus, Battery) -> BatteryStatus
	"""
	Read the modbus registers containing the battery's status info.
	"""

	logging.debug('reading battery status')

	with modbus:
		data = read_modbus_registers(modbus, battery.slave_address)
		return BatteryStatus(battery, data.registers)


def publish_values_on_dbus(service, battery_signals, battery_statuses):
	# type: (DBusService, Iterable[BatterySignal], Iterable[BatteryStatus]) -> ()

	publish_individuals(service, battery_signals, battery_statuses)
	publish_aggregates(service, battery_signals, battery_statuses)


def publish_aggregates(service, signals, battery_statuses):
	# type: (DBusService, Iterable[BatterySignal], Iterable[BatteryStatus]) -> ()

	for s in signals:
		if s.aggregate is None:
			continue
		values = [s.get_value(battery_status) for battery_status in battery_statuses]
		value = s.aggregate(values)

		service.own_properties.set(s.dbus_path, value, s.unit)


def publish_individuals(service, signals, battery_statuses):
	# type: (DBusService, Iterable[BatterySignal], Iterable[BatteryStatus]) -> ()

	for signal in signals:
		for battery_status in battery_statuses:
			address = battery_status.battery.slave_address
			dbus_path = '/_Battery/' + str(address) + signal.dbus_path
			value = signal.get_value(battery_status)
			service.own_properties.set(dbus_path, value, signal.unit)


def publish_service_signals(service, signals):
	# type: (DBusService, Iterable[ServiceSignal]) -> NoReturn

	for signal in signals:
		service.own_properties.set(signal.dbus_path, signal.value, signal.unit)


def upload_status_to_innovenergy(sock, statuses):
	# type: (socket, Iterable[BatteryStatus]) -> bool

	logging.debug('upload status')

	try:
		for s in statuses:
			sock.sendto(s.serialize(), (cfg.INNOVENERGY_SERVER_IP, cfg.INNOVENERGY_SERVER_PORT))
	except:
		logging.debug('FAILED')
		return False
	else:
		return True


def print_usage():
	print ('Usage:   ' + __file__ + ' <serial device>')
	print ('Example: ' + __file__ + ' ttyUSB0')


def parse_cmdline_args(argv):
	# type: (List[str]) -> str

	if len(argv) == 0:
		logging.info('missing command line argument for tty device')
		print_usage()
		sys.exit(1)

	return argv[0]


def reset_batteries(modbus, batteries):
	# type: (Modbus, Iterable[Battery]) -> NoReturn

	logging.info('Resetting batteries...')

	for battery in batteries:

		result = modbus.write_registers(RESET_REGISTER, [1], unit=battery.slave_address)

		# expecting a ModbusIOException (timeout)
		# BMS can no longer reply because it is already reset
		success = isinstance(result, ModbusIOException)

		outcome = 'successfully' if success else 'FAILED to'
		logging.info('Battery {0} {1} reset'.format(str(battery.slave_address), outcome))

	logging.info('Shutting down fz-sonick driver')
	exit(0)


alive = True  # global alive flag, watchdog_task clears it, update_task sets it


def create_update_task(modbus, service, batteries):
	# type: (Modbus, DBusService, Iterable[Battery]) -> Callable[[],bool]
	"""
	Creates an update task which runs the main update function
	and resets the alive flag
	"""
	_socket = init_udp_socket()
	_signals = signals.init_battery_signals()

	def update_task():
		# type: () -> bool

		global alive

		logging.debug('starting update cycle')

		# Checking if we have excess power and if so charge batteries more

		target = service.remote_properties.get(get_service(SETTINGS_SERVICE_PREFIX) + '/Settings/CGwacs/AcPowerSetPoint').value or 0
		actual = service.remote_properties.get(get_service(INVERTER_SERVICE_PREFIX) + '/Ac/Out/P').value or 0

		if actual>target:
			service.own_properties.set('/Info/MaxChargeCurrent').value = min([battery.i_max for battery in batteries])

		if service.own_properties.get('/ResetBatteries').value == 1:
			reset_batteries(modbus, batteries)

		statuses = [read_battery_status(modbus, battery) for battery in batteries]

		publish_values_on_dbus(service, _signals, statuses)
		upload_status_to_innovenergy(_socket, statuses)

		logging.debug('finished update cycle\n')

		alive = True

		return True

	return update_task


def create_watchdog_task(main_loop):
	# type: (DBusGMainLoop) -> Callable[[],bool]
	"""
	Creates a Watchdog task that monitors the alive flag.
	The watchdog kills the main loop if the alive flag is not periodically reset by the update task.
	Who watches the watchdog?
	"""

	def watchdog_task():
		# type: () -> bool

		global alive

		if alive:
			logging.debug('watchdog_task: update_task is alive')
			alive = False
			return True
		else:
			logging.info('watchdog_task: killing main loop because update_task is no longer alive')
			main_loop.quit()
			return False

	return watchdog_task

def get_service(self, prefix: str) -> Optional[unicode]:
	service = next((s for s in self.available_services if s.startswith(prefix)), None)
	if service is None:
		raise Exception('no service matching ' + prefix + '* available')

	return service


def main(argv):
	# type: (List[str]) -> ()

	logging.basicConfig(level=cfg.LOG_LEVEL)
	logging.info('starting ' + __file__)

	tty = parse_cmdline_args(argv)
	modbus = init_modbus(tty)

	batteries = identify_batteries(modbus)

	if len(batteries) <= 0:
		sys.exit(2)

	service = DBusService(service_name=cfg.SERVICE_NAME_PREFIX + tty)

	service.own_properties.set('/ResetBatteries', value=False, writable=True)  # initial value = False

	main_loop = GLib.MainLoop()

	service_signals = signals.init_service_signals(batteries)
	publish_service_signals(service, service_signals)

	update_task = create_update_task(modbus, service, batteries)
	update_task()                        # run it right away, so that all props are initialized before anyone can ask
	watchdog_task = create_watchdog_task(main_loop)

	GLib.timeout_add(cfg.UPDATE_INTERVAL * 2, watchdog_task, priority = GLib.PRIORITY_LOW)  # add watchdog first
	GLib.timeout_add(cfg.UPDATE_INTERVAL, update_task, priority = GLib.PRIORITY_LOW)        # call update once every update_interval

	logging.info('starting gobject.MainLoop')
	main_loop.run()
	logging.info('gobject.MainLoop was shut down')

	sys.exit(0xFF)  # reaches this only on error


main(sys.argv[1:])