import threading
import time
from datetime import datetime
from typing import Union

import geopy
import geopy.distance
from circuitbreaker import circuit
from daf import DAF

# Lat, Long
STARTING_POINT = geopy.Point(48.853, 2.349)
# in km/h
STARTING_VELOCITY = 130
# Driving direction in degrees: 0=N, 90=E, 180=S, 270=W
BEARING = 0
# Scale speed of vehicles by factor x
SCALING = 100
# Interval between status updates in seconds (is not scaled)
UPDATE_INTERVAL = 1
# At x km the NCE shall happen
NCE_KM = 30
# Time in seconds to recover from NCE (will be scaled)
TIME_TO_RECOVER = 100
# Resets vehicle at km x
RESET_KM = 50


class Vehicle:
    # vehicle identification number
    vin: str
    # velocity in km/h
    velocity: float
    # stores the timestamp most recently used to calculate driving distance
    last_update: Union[datetime, None]
    # marks if vehicle is currently driving, a new one isn't, has to be started via self.start_driving()
    driving: bool = False
    # stores last velocity before NCE, is used to recover after NCE
    _last_velocity: float
    # stores the so-far driven kilometers
    _driven_kms: int
    # stores the starting point for resetting the vehicle
    _starting_point: geopy.Point
    # stores the gps_location, shall be accessed by gps_location, where the actual value is calculated and returned
    _gps_location: geopy.Point
    # stores if nce possible
    _nce_possible = True
    # stores if nce already happened, it only happens (up to) once
    _nce_happened = False
    # continuous driving thread
    _t: threading.Thread
    # NCE recovery thread
    _rt: threading.Thread

    def __init__(self,
                 vin: str,
                 starting_point: geopy.Point = STARTING_POINT,
                 starting_velocity: float = STARTING_VELOCITY):
        self.vin = vin
        self._starting_point = starting_point
        self._gps_location = starting_point
        self.velocity = starting_velocity

    @property
    def nce(self):
        """
        On accessing this property, it is calculated if the NCE shall happen. NCE only happens up to once per route.
        :return: True if NCE invoked, otherwise False
        """
        if self._nce_possible and not self._nce_happened:
            if self._driven_kms >= NCE_KM:
                self._nce_happened = True
                self._last_velocity = self.velocity
                self.velocity = 0

                def _sleep_and_recover():
                    recover_in = TIME_TO_RECOVER / SCALING
                    print('\nNCE !!! Recovering in {} (scaled) seconds.\n'.format(recover_in))
                    time.sleep(recover_in)
                    print('\nRecovered.\n')
                    self.velocity = self._last_velocity

                self._rt = threading.Thread(target=_sleep_and_recover)
                self._rt.start()
                return True

        return False

    @nce.setter
    def nce(self, val):
        self._nce_happened = val

    @property
    def daf(self):
        """
        :return: "Datenaufzeichnung für automatisiertes Fahren" (DAF) object
        """
        return DAF(vehicle_identification_number=self.vin,
                   gps_location=self.gps_location,
                   near_crash_event=self.nce,
                   velocity=self.velocity,
                   timestamp=self.last_update,
                   )

    @property
    def gps_location(self):
        """
        Update self.gps_location with given speed in km/h and the driven time in seconds
        :param velocity: in km/h
        :param time: in seconds
        :param bearing: direction in degrees: 0=N, 90=E, 180=S, 270=W
        """
        # Define starting point.
        start = self._gps_location

        # Get old and updated timestamps
        old_timestamp = self.last_update
        updated_timestamp = datetime.now()
        self.last_update = updated_timestamp

        # get driving time between timestamps (in seconds)
        driving_time = (updated_timestamp - old_timestamp).total_seconds()

        # reached distance in kilometers: convert km/h to km/s and multiply by driving time
        kilometers = self.velocity / 3600 * driving_time * SCALING

        # Define a general distance object, initialized with a distance of 1 km.
        d = geopy.distance.distance(kilometers=kilometers)

        # Use the `destination` method with a bearing of bearing degrees
        # in order to go from point `start` to kilometers km bearing.
        self._gps_location = d.destination(point=start, bearing=BEARING)

        # update driven kilometers
        self._driven_kms += kilometers
        return self._gps_location

    @property
    def driven_kms(self):
        return '{}km'.format(round(self._driven_kms, 2))

    def start_driving(self):
        """
        Starts a thread responsible for driving. This thread continuously updates internal values and
        informs the message broker about the current state (DAF) of the vehicle.
        """
        print('Start driving ... SCALING: x{}\n\n'.format(SCALING))
        self.last_update = datetime.now()
        self._driven_kms = 0

        self._t = threading.Thread(target=self.drive)
        self._t.start()

    def drive(self):
        """
        Drive until not self.driving == update status every UPDATE_INTERVAL seconds.
        """
        self.driving = True
        while self.driving:
            self.check_reset()
            self.send_status_update()
            time.sleep(UPDATE_INTERVAL)

    def stop_driving(self):
        """
        Set self.driving to stop driving thread gracefully.
        """
        self.driving = False
        self._gps_location = self._starting_point
        self._driven_kms = 0

    def check_reset(self):
        """
        Checks if end of route is reached and resets vehicle to starting conditions.
        Afterwards, the vehicle is still driving, but again from start.
        """
        if self._driven_kms >= RESET_KM:
            print('\n\nEnd of route reached ... resetting and restarting vehicle')
            self._gps_location = self._starting_point
            self._driven_kms = 0
            self.last_update = datetime.now()
            self.nce = False

    @circuit(failure_threshold=10, expected_exception=ConnectionError)
    def send_status_update(self):
        # TODO inform the message broker about the current status
        print(self.driven_kms, '\t', self.daf)

    # TODO adapt the vehicle's velocity to the suggestion of the orchestration service
    def new_velocity(self):
        ...


if __name__ == "__main__":
    v1 = Vehicle(vin='SB164ABN1PE082986')
    v1.start_driving()
    # stop manually