#!/usr/bin/env python3

import os
import datetime
from time import sleep
import requests
import astral
from astral.sun import sun
from pytz import utc

CHANNEL = os.environ["SUNBOT_ANNOUNCE_CHANNEL"]
AUTHORIZATION = "Bearer " + os.environ["SUNBOT_ANNOUNCE_MATTERMOST_TOKEN"]
URL = os.environ["SUNBOT_ANNOUNCE_MATTERMOST_API_ENDPOINT"] + "/v4/posts"

LOCATION = astral.LocationInfo("Gent", "Belgium", "Europe/Brussels", 51.05, 3.72)

def in_timezone(d):
	return d.astimezone(LOCATION.tzinfo)


def post(message):
	payload = {
		"channel_id": CHANNEL,
		"message": message
	}
	print("Posting " + str(payload), flush=True)
	r = requests.post(URL, json=payload, headers={"Authorization": AUTHORIZATION})
	r.raise_for_status()


def format_in(diff):
	total_minutes = round(diff.total_seconds() / 60)
	hours, minutes = divmod(total_minutes, 60)
	return "{}h{}".format(hours, minutes)


def wait_until(t, now):
	seconds = (t - now).total_seconds()
	print("Waiting {} seconds until {}".format(seconds, in_timezone(t)), flush=True)
	sleep(seconds)


def announce_sunrise(today):
	print("Announcing sunrise", flush=True)
	now = datetime.datetime.now(utc)
	post(":sunrise: De zon komt op in Gent!\nZonnemiddag om {:%H:%M %Z} (binnen {})\nZonsondergang om {:%H:%M %Z} (binnen {})".format(
		in_timezone(today["noon"]),   format_in(today["noon"]   - now),
		in_timezone(today["sunset"]), format_in(today["sunset"] - now),
	))


def announce_sunset(tomorrow):
	print("Announcing sunset", flush=True)
	now = datetime.datetime.now(utc)
	post(":city_sunset: De zon gaat onder in Gent!\nZonsopkomst om {:%H:%M %Z} (binnen {})".format(
		in_timezone(tomorrow["sunrise"]), format_in(tomorrow["sunrise"] - now),
	))


def main():
	print("Starting Sunbot", flush=True)
	while True:
		now = datetime.datetime.now(utc)
		today = sun(LOCATION.observer, date=now.date())
		tomorrow = sun(LOCATION.observer, date=now.date() + datetime.timedelta(days=1))

		if now >= today["sunset"]:
			wait_until(tomorrow["sunrise"], now)
			announce_sunrise(tomorrow)

		elif now >= today["sunrise"]:
			wait_until(today["sunset"], now)
			announce_sunset(tomorrow)

		else:
			wait_until(today["sunrise"], now)
			announce_sunrise(today)


if __name__ == "__main__":
	main()