from threading import Timer
from multiprocessing import Process
from typing import Iterable, Optional

import Leap

from platypush.context import get_bus
from platypush.message.event.sensor.leap import (
    LeapFrameEvent,
    LeapFrameStartEvent,
    LeapFrameStopEvent,
    LeapConnectEvent,
    LeapDisconnectEvent,
)
from platypush.plugins import RunnablePlugin


class LeapPlugin(RunnablePlugin):
    """
    Integration to handle events from a `Leap Motion
    <https://www.leapmotion.com/>`_ device to track hands and
    gestures.

    Note that the default SDK is not compatible with Python 3. Follow the
    instructions on https://github.com/BlackLight/leap-sdk-python3 to build the
    Python 3 module.

    Also, you'll need the Leap driver and utils installed on your OS (follow
    instructions at https://www.leapmotion.com/setup/) and the `leapd` daemon
    running to recognize your controller.

    Requires:

        * The Leap Motion SDK compiled with Python 3 support, see my port at
            https://github.com:BlackLight/leap-sdk-python3.git
        * The ``leapd`` daemon to be running and your Leap Motion connected

    """

    _listener_proc = None

    def __init__(
        self,
        position_ranges: Optional[Iterable[Iterable[float]]] = None,
        position_tolerance: float = 0.0,
        poll_interval: Optional[float] = 0.1,
        **kwargs
    ):
        """
        :param position_ranges: It specifies how wide the hand space (x, y and
            z axes) should be in millimiters.

            Default::

                [
                    [-300.0, 300.0],  # x axis
                    [25.0, 600.0],    # y axis
                    [-300.0, 300.0],  # z axis
                ]
        :param position_tolerance: % of change between a frame and the next to
            really consider the next frame as a new one (default: 0).
        :param poll_interval: How often the plugin should generate and push
            events (default: at most one event each 0.1 seconds). Note that a
            Leap Motion generates events with a very high throughput, so you
            may want to set a higher value if you want to throttle the events
            and avoid flooding the bus.
        """
        super().__init__(poll_interval=poll_interval, **kwargs)

        if position_ranges is None:
            position_ranges = [
                [-300.0, 300.0],  # x axis
                [25.0, 600.0],  # y axis
                [-300.0, 300.0],  # z axis
            ]

        self.position_ranges = position_ranges
        self.position_tolerance = position_tolerance

    def main(self):
        def _listener_process():
            listener = LeapListener(
                position_ranges=self.position_ranges,
                position_tolerance=self.position_tolerance,
                frames_throttle_secs=self.poll_interval,
                logger=self.logger,
            )

            controller = Leap.Controller()

            if not controller:
                raise RuntimeError(
                    'No Leap Motion controller found - is your '
                    + 'device connected and is leapd running?'
                )

            controller.add_listener(listener)
            self.logger.info('Leap Motion device initialized')

            try:
                self.wait_stop()
            except KeyboardInterrupt:
                self.logger.info('Terminating Leap Motion listener')

        while not self.should_stop():
            self.wait_stop(1)
            self._listener_proc = Process(target=_listener_process)
            self._listener_proc.start()
            self._listener_proc.join()
            self._listener_proc = None


class LeapFuture(Timer):
    def __init__(self, seconds, listener, event):
        self.listener = listener
        self.event = event
        super().__init__(seconds, self._callback_wrapper())

    def _callback_wrapper(self):
        def _callback():
            self.listener._send_event(self.event)  # pylint: disable=protected-access

        return _callback


class LeapListener(Leap.Listener):
    def __init__(
        self, position_ranges, position_tolerance, logger, frames_throttle_secs=None
    ):
        super().__init__()

        self.prev_frame = None
        self.position_ranges = position_ranges
        self.position_tolerance = position_tolerance
        self.frames_throttle_secs = frames_throttle_secs
        self.logger = logger
        self.running_future = None

    def _send_event(self, event):
        get_bus().post(event)

    def send_event(self, event):
        if self.frames_throttle_secs:
            if not self.running_future or not self.running_future.is_alive():
                self.running_future = LeapFuture(
                    seconds=self.frames_throttle_secs, listener=self, event=event
                )
                self.running_future.start()
        else:
            self._send_event(event)

    def on_init(self, *_, **__):
        self.prev_frame = None
        self.logger.info('Leap controller listener initialized')

    def on_connect(self, *_, **__):
        self.logger.info('Leap controller connected')
        self.prev_frame = None
        self.send_event(LeapConnectEvent())

    def on_disconnect(self, *_, **__):
        self.logger.info('Leap controller disconnected')
        self.prev_frame = None
        self.send_event(LeapDisconnectEvent())

    def on_exit(self, *_, **__):
        self.logger.info('Leap listener terminated')

    def on_frame(self, controller):
        frame = controller.frame()

        if len(frame.hands) > 0:
            hands = self._flatten_hands(frame)
            if hands:
                if not self.prev_frame:
                    self.send_event(LeapFrameStartEvent())
                self.send_event(LeapFrameEvent(hands=hands))
            self.prev_frame = frame
        else:
            if self.prev_frame:
                self.send_event(LeapFrameStopEvent())
            self.prev_frame = None

    def _flatten_hands(self, frame):
        return [
            {
                'confidence': hand.confidence,
                'direction': [hand.direction[0], hand.direction[1], hand.direction[2]],
                'id': hand.id,
                'is_left': hand.is_left,
                'is_right': hand.is_right,
                'palm_normal': [
                    hand.palm_normal[0],
                    hand.palm_normal[1],
                    hand.palm_normal[2],
                ],
                'palm_position': self._normalize_position(hand.palm_position),
                'palm_velocity': [
                    hand.palm_velocity[0],
                    hand.palm_velocity[1],
                    hand.palm_velocity[2],
                ],
                'palm_width': hand.palm_width,
                'sphere_center': [
                    hand.sphere_center[0],
                    hand.sphere_center[1],
                    hand.sphere_center[2],
                ],
                'sphere_radius': hand.sphere_radius,
                'stabilized_palm_position': self._normalize_position(
                    hand.stabilized_palm_position
                ),
                'time_visible': hand.time_visible,
                'wrist_position': self._normalize_position(hand.wrist_position),
            }
            for i, hand in enumerate(frame.hands)
            if hand.is_valid
            and (
                len(frame.hands) != len(self.prev_frame.hands)
                or self._position_changed(
                    old_position=self.prev_frame.hands[i].stabilized_palm_position,
                    new_position=hand.stabilized_palm_position,
                )
                if self.prev_frame
                else True
            )
        ]

    def _normalize_position(self, position):
        # Normalize absolute position onto a hemisphere centered in (0,0)
        # having x_range = z_range = [-100, 100], y_range = [0, 100]

        return [
            self._scale_scalar(
                value=position[0],
                range=self.position_ranges[0],
                new_range=[-100.0, 100.0],
            ),
            self._scale_scalar(
                value=position[1], range=self.position_ranges[1], new_range=[0.0, 100.0]
            ),
            self._scale_scalar(
                value=position[2],
                range=self.position_ranges[2],
                new_range=[-100.0, 100.0],
            ),
        ]

    @staticmethod
    def _scale_scalar(value, range, new_range):
        if value < range[0]:
            value = range[0]
        if value > range[1]:
            value = range[1]

        return ((new_range[1] - new_range[0]) / (range[1] - range[0])) * (
            value - range[0]
        ) + new_range[0]

    def _position_changed(self, old_position, new_position):
        return (
            abs(old_position[0] - new_position[0]) > self.position_tolerance
            or abs(old_position[1] - new_position[1]) > self.position_tolerance
            or abs(old_position[2] - new_position[2]) > self.position_tolerance
        )


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