import logging
from datetime import datetime

import pytz

from core.data_store import DATA_STORE


class SIGRefDataProvider:
    """Generic SIG reference data provider class. Subclasses of this query the individual URLs or files for data."""

    def __init__(self, sig_name, provider_config):
        """Constructor"""

        self.sig_name = sig_name
        self.enabled = provider_config["enabled"]
        self.last_update_time = datetime.min.replace(tzinfo=pytz.UTC)
        self.status = "Not Started" if self.enabled else "Disabled"
        self.reference_count = 0
        self._stop = False


    def start(self):
        """Start the provider. This should return immediately after spawning threads to access the remote resources"""

        raise NotImplementedError("Subclasses must implement this method")


    def stop(self):
        """Stop any threads and prepare for application shutdown. Subclasses should implement this method and call
        super()."""

        self._stop = True

    def _add_data(self, new_data):
        """Add all the provided reference data objects to the data store."""

        # with transact() batches all writes together to save making thousands of individual sqlite writes
        with DATA_STORE.sigrefs.transact():
            for d in new_data:
                DATA_STORE.sigrefs.set(self.sig_name + ":" + d.id, d)

                # For the big data sources, loading will take a few minutes. If we want to shut down the software neatly
                # within the first few minutes of startup, we need a way to abort this expensive process of filling up the
                # disk cache.
                if self._stop:
                    break

        self.reference_count = len(new_data)
        logging.info(f"Loaded %d references for %s into the data store.", self.reference_count, self.sig_name)