"""API for Google Mail bound to Home Assistant OAuth."""
from google.auth.exceptions import RefreshError
from google.oauth2.credentials import Credentials
from googleapiclient.discovery import Resource, build

from homeassistant.const import CONF_ACCESS_TOKEN
from homeassistant.helpers import config_entry_oauth2_flow


class AsyncConfigEntryAuth:
    """Provide Google Mail authentication tied to an OAuth2 based config entry."""

    def __init__(
        self,
        oauth2_session: config_entry_oauth2_flow.OAuth2Session,
    ) -> None:
        """Initialize Google Mail Auth."""
        self.oauth_session = oauth2_session

    @property
    def access_token(self) -> str:
        """Return the access token."""
        return self.oauth_session.token[CONF_ACCESS_TOKEN]

    async def check_and_refresh_token(self) -> str:
        """Check the token."""
        await self.oauth_session.async_ensure_token_valid()
        return self.access_token

    async def get_resource(self) -> Resource:
        """Get current resource."""
        try:
            credentials = Credentials(await self.check_and_refresh_token())
        except RefreshError as ex:
            self.oauth_session.config_entry.async_start_reauth(self.oauth_session.hass)
            raise ex
        return build("gmail", "v1", credentials=credentials)