import logging
from datetime import datetime
from threading import Thread, Event

import pytz
import requests

from core.constants import HTTP_HEADERS
from solarconditionsproviders.solar_conditions_provider import SolarConditionsProvider


class HTTPSolarConditionsProvider(SolarConditionsProvider):
    """Generic solar conditions provider for providers that request data via HTTP(S). Subclasses implement
    _http_response_to_solar_conditions() to parse the specific API response format."""

    def __init__(self, provider_config, url, poll_interval):
        super().__init__(provider_config)
        self._url = url
        self._poll_interval = poll_interval
        self._thread = None
        self._stop_event = Event()

    def start(self):
        logging.info(
            "Set up query of " + self.name + " solar conditions API every " + str(self._poll_interval) + " seconds.")
        self._thread = Thread(target=self._run, daemon=True)
        self._thread.start()

    def stop(self):
        self._stop_event.set()

    def _run(self):
        while True:
            self._poll()
            if self._stop_event.wait(timeout=self._poll_interval):
                break

    def _poll(self):
        try:
            logging.debug("Polling " + self.name + " solar conditions API...")
            http_response = requests.get(self._url, headers=HTTP_HEADERS)
            new_data = self._http_response_to_solar_conditions(http_response)
            self.update_data(new_data)

            self.status = "OK"
            self.last_update_time = datetime.now(pytz.UTC)
            logging.debug("Received data from " + self.name + " solar conditions API.")

        except Exception:
            self.status = "Error"
            logging.exception("Exception in HTTP Solar Conditions Provider (" + self.name + ")")
            self._stop_event.wait(timeout=1)

    def _http_response_to_solar_conditions(self, http_response):
        """Convert an HTTP response into solar conditions data. Returns a dict mapping SolarConditions field
        names to their new values, or None if the response could not be parsed. Only the fields returned will
        be updated on the shared SolarConditions object; any fields not included will be left unchanged."""

        raise NotImplementedError("Subclasses must implement this method")