from typing import Any, Union

import astropy.units as u
from astropy.coordinates import EarthLocation
from astropy.time import Time
import threading
import subprocess

from vlsr import doppler_frequency
from camrasdevices import LocalOscillator

freq_hi = 1420.405751 * u.MHz


def doppler_harm(sky_coordinate, time, tracking_frequency, location, variant):
    ra = sky_coordinate.ra.to(u.rad).value
    dec = sky_coordinate.dec.to(u.rad).value
    t = time.unix
    dt_lat = location.lat.to(u.rad).value
    dt_lon = location.lon.to(u.rad).value
    dt_alt = location.height.to(u.m).value
    argstring = "{ra} {dec} 2000 {time} {dt_lat} {dt_lon} {dt_alt}".format(
        ra=ra, dec=dec, time=t, dt_lat=dt_lat, dt_lon=dt_lon, dt_alt=dt_alt)

    doppler_executable = "/home/harm/bin/doppler_" + variant

    doppler_cmd = doppler_executable + " " + argstring \
        + " " + str(tracking_frequency.to(u.MHz).value)
    freq_doppler = float(subprocess.Popen(doppler_cmd,
                                          stdout=subprocess.PIPE,
                                          shell=True
                                          ).stdout.read())

    return freq_doppler * u.MHz


def doppler_harm_bl(sky_coordinate, time, tracking_frequency, location):
    return doppler_harm(sky_coordinate, time, tracking_frequency, location, 'bl')


def doppler_harm_mb(sky_coordinate, time, tracking_frequency, location):
    return doppler_harm(sky_coordinate, time, tracking_frequency, location, 'mb')


def track_doppler(dt, lo,
                  tracking_frequency=freq_hi,
                  doppler_function=doppler_frequency,
                  exit_event=None,
                  timeout=0.3):
    """Sets the Local Oscillator to a frequency to correct for Doppler shift. When exit event is
    set, return the LO frequency to 1GHz.

    Args:
        dt (Telescope): a Telescope instance to read the current pointing from.
        lo (LocalOscillator): the local oscillator of which the frequency will be set.
        doppler_function (function): a function that computes the doppler frequency.
            This function gets a SkyCoord and a time (float), and should return a frequency Quantity
        timeout (float): timeout between updates of the Local Oscillator
    """

    if not exit_event:
        exit_event = threading.Event()
    dt_lat = 52.812019 * u.deg
    dt_lon = 6.396169 * u.deg
    dt_alt = 25.0 * u.m

    dt_loc = EarthLocation.from_geodetic(lat=dt_lat, lon=dt_lon, height=dt_alt)

    while not exit_event.is_set():
        sky_coordinate = dt.radec
        if sky_coordinate:
            freq_doppler = doppler_function(sky_coordinate, Time.now(), tracking_frequency, dt_loc)
            dfreq = 1 * u.GHz + tracking_frequency - freq_doppler
            lo.frequency = dfreq
        exit_event.wait(timeout=timeout)
    lo.frequency = 1 * u.GHz
    exit_event.clear()