#!/usr/bin/python2 -u
# coding=utf-8

import logging
import re
import socket
import sys
import gobject
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


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')

                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 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 = gobject.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)

        gobject.timeout_add(cfg.UPDATE_INTERVAL * 2, watchdog_task, priority = gobject.PRIORITY_LOW)  # add watchdog first
        gobject.timeout_add(cfg.UPDATE_INTERVAL, update_task, priority = gobject.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:])