private void getDriverLocation() {

    retrofitInterface.getLiveTripDetails(routeDetails.getId()).enqueue(new Callback<List<TripDetails>>() {
        @Override
        public void onResponse(Call<List<TripDetails>> call, Response<List<TripDetails>> response) {
            if (response.isSuccessful()){
                if (response.body() != null && response.body().size() > 0) {
                    for (int i = 0; i < response.body().size(); i++) {
                        tripDetails = response.body().get(i);
                    }

                    double lat = tripDetails.getLastLat();
                    double lng = tripDetails.getLastLong();

                    if (lat != 0.0 && lng != 0.0) {

                        if (user_marker != null && user_marker.isVisible()) {
                            user_marker.remove();
                        }

                        bus_location = new LatLng(tripDetails.getLastLat(),
                                tripDetails.getLastLong());

                        if (!busLocationRequested) {

                            oldLocation = bus_location;

                            bus_marker = mMap.addMarker(new MarkerOptions()
                                    .position(bus_location)
                                    .title(routeDetails.getDriverName())
                                    .snippet(routeDetails.getDriverMobileNo())
                                    .rotation(toLocation(bus_location).getBearing())
                                    .anchor(0.5f, 0.5f)
                                    .flat(true)
                                    .icon(vectorToBitmap(R.drawable.ic_bus_top_view)));

                            CameraPosition camPos = CameraPosition
                                    .builder(mMap.getCameraPosition())
                                    .bearing(toLocation(bus_location).getBearing())
                                    .target(bus_location)
                                    .zoom(18)
                                    .build();
                            mMap.animateCamera(CameraUpdateFactory.newCameraPosition(camPos));

                            startTimer();
                        }
                        else {
                            updateMarker();
                        }

                        addMarkers();

                    }
                    else {
                        displayUserLocation();
                    }
                }
                else {
                    displayUserLocation();
                }
            }
        }

        @Override
        public void onFailure(Call<List<TripDetails>> call, Throwable t) {

        }
    });
}

private void updateMarker() {

    float rotation = (float) SphericalUtil.computeHeading(oldLocation, bus_location);
    rotateMarker(bus_markers.get(0), toLocation(bus_location), rotation);

    LatLngInterpolator latLngInterpolator = new LatLngInterpolator.Spherical();
    MarkerAnimation.animateMarkerToICS(bus_markers.get(0), bus_location, latLngInterpolator);

    oldLocation = bus_location;
}

public void rotateMarker(final Marker marker, final Location destination, final float rotation) {
    if (marker != null) {
        final LatLng startPosition = marker.getPosition();
        final LatLng endPosition = new LatLng(destination.getLatitude(), destination.getLongitude());

        final float startRotation = marker.getRotation();

        final LatLngInterpolator latLngInterpolator = new LatLngInterpolator.LinearFixed();
        ValueAnimator valueAnimator = ValueAnimator.ofFloat(0, 1);
        valueAnimator.setDuration(1500); // duration 1.5 seconds
        valueAnimator.setInterpolator(new LinearInterpolator());
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override public void onAnimationUpdate(ValueAnimator animation) {
                try {
                    float v = animation.getAnimatedFraction();

                    LatLng newPosition = latLngInterpolator.interpolate(v, startPosition, endPosition);
                    float bearing = computeRotation(v, startRotation, rotation);

                    /*marker.setPosition(newPosition);*/
                    marker.setRotation(bearing);

                } catch (Exception ex) {
                    // I don't care atm..
                }
            }
        });
        valueAnimator.start();
    }
}
private static float computeRotation(float fraction, float start, float end) {
    float normalizeEnd = end - start; // rotate start to 0
    float normalizedEndAbs = (normalizeEnd + 360) % 360;

    float direction = (normalizedEndAbs > 180) ? -1 : 1; // -1 = anticlockwise, 1 = clockwise
    float rotation;
    if (direction > 0) {
        rotation = normalizedEndAbs;
    } else {
        rotation = normalizedEndAbs - 360;
    }

    float result = fraction * rotation + start;
    return (result + 360) % 360;
}

private void displaySchoolLocation(){
    busLocationRequested = false;

    if (bus_markers != null && bus_markers.isVisible() {
        bus_markers.remove();
    }

    handler.removeCallbacks(runnable);

    UserDetails userDetails = getLocalStorageData().getUserDetails();
    LatLng user_location = userDetails.getLatLng();
    user_marker = mMap.addMarker(new MarkerOptions()
            .position(user_location)
            .title(userDetails.getName())
            .anchor(0.5f, 0.5f)
            .icon(vectorToBitmap(R.drawable.ic_user)));

    String message = "The bus has not yet started. Please come back by " + routeDetails.getDropTime();
    String bText = getString(R.string.check_again);
    final Snackbar snackbar = Snackbar.make(mLayout, message, LENGTH_INDEFINITE);
    snackbar.setAction(bText, new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            snackbar.dismiss();
            getDriverLocation();
        }
    });
    snackbar.show();
}