import os

from google.auth.credentials import AnonymousCredentials
from google.cloud.bigtable import Client
from google.cloud.bigtable.instance import Instance
from google.cloud.bigtable.table import Table

from delphi_api.const import BIGTABLE_APP_PROFILE_ID, BIGTABLE_INSTANCE_ID, ENVIRONMENT


class BigTableClient:
    @staticmethod
    def get_client(**kwargs):
        """
        Available kwargs:
            project=None,
            credentials=None,
            read_only=False,
            admin=False,
            client_info=_CLIENT_INFO,
            client_options=None,
            admin_client_options=None,
            channel=None,
        """
        if os.getenv('BIGTABLE_EMULATOR_HOST') or ENVIRONMENT == 'test':  # pragma: no cover
            # This for testing, and here due to a bug in the gcloud client that does not
            # _only_ read the environment variable to establish a connection to the emulator
            return Client(project='emulated-project',
                          credentials=AnonymousCredentials(), admin=True)
        return Client(**kwargs)


# Reuse a single service object to reduce open files/connections
_BIGTABLE_READ_ONLY_CLIENT = BigTableClient.get_client(read_only=True)


class BigTableService:

    def __init__(self, table_id: str, instance_id: str = BIGTABLE_INSTANCE_ID,
                 app_profile_id: str = BIGTABLE_APP_PROFILE_ID):
        """Class to include config and encapsulate BigTable API

        Args:
            table_id: BigTable TABLE_ID
            instance_id: BigTable INSTANCE_ID
            app_profile_id: BigTable application profile ID
        """
        self.table_id = table_id
        self.instance_id = instance_id
        self.app_profile_id = app_profile_id

    @staticmethod
    def _get_client(**kwargs):
        return BigTableClient.get_client(**kwargs)

    @property
    def client(self) -> Client:
        return _BIGTABLE_READ_ONLY_CLIENT

    @property
    def instance(self) -> Instance:
        return self.client.instance(self.instance_id)

    @property
    def table(self) -> Table:
        return self.instance.table(self.table_id, app_profile_id=self.app_profile_id)

    @property
    def admin_client(self) -> Client:
        return BigTableClient.get_client(admin=True)

    @property
    def admin_instance(self) -> Instance:
        return self.admin_client.instance(self.instance_id)

    @property
    def admin_table(self) -> Table:
        return self.admin_instance.table(self.table_id, app_profile_id=self.app_profile_id)