"""Keep a paid Space active only while acknowledged background work remains."""
import logging
import os
import threading

LOG = logging.getLogger(__name__)


class WorkKeepAlive:
    def __init__(self, has_pending, *, interval=120, host=None, token=None, request=None):
        self.has_pending = has_pending
        self.interval = interval
        self.host = (host if host is not None else os.environ.get('SPACE_HOST', '')).split(',')[0].strip()
        self.token = token if token is not None else os.environ.get('HF_TOKEN', '')
        self.request = request
        self._stop = threading.Event()
        self._thread = None
        self._warned = False

    def tick(self):
        if not self.host or '/' in self.host or not self.has_pending():
            return False
        import requests
        headers = {'Authorization': 'Bearer '+self.token} if self.token else {}
        try:
            response = (self.request or requests.get)(
                'https://'+self.host+'/api/history/status', headers=headers,
                timeout=15, allow_redirects=False)
            if response.status_code == 200:
                self._warned = False
                return True
        except requests.RequestException:
            pass
        if not self._warned:
            LOG.warning('Background work is saved; the Space activity check is temporarily unavailable.')
            self._warned = True
        return False

    def start(self):
        if self._thread is not None:
            return

        def run():
            while not self._stop.wait(self.interval):
                self.tick()

        self._thread = threading.Thread(target=run, name='active-background-work', daemon=True)
        self._thread.start()

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