"""Adapter for the data warehouse."""

from snowflake import connector

from accounting import config


class SnowflakeAdapter():
    """Creates a snowflake connector.

    Allows select statements to be executed against snowflake.
    The connection is lazy loaded.
    """

    def __init__(self):
        """Set lazy load flag."""
        self._init = False

    def __del__(self):
        """Teardown connection."""
        try:
            self._cursor.close()
        except AttributeError:
            pass

        try:
            self._connection.close()
        except AttributeError:
            pass

    def _connect(self):
        """Configure a usable connection for querying."""
        self._connection = self._get_connection()
        self._cursor = self._connection.cursor()

    def _get_connection(self):
        """Return a raw connection to snowflake."""
        return connector.connect(
            user=config.WAREHOUSE_USER, password=config.WAREHOUSE_PASS,
            account=config.WAREHOUSE_ACCOUNT)

    def execute(self, sql):
        """Execute a select statement against snowflake.

        Args:
            sql (str): A valid snowflake sql select statement.

        Returns:
            Tuple[]: A list of Tuples with values ordered according to the sql.

        """
        if not self._init:
            self._connect()
            self._init = True
        return self._cursor.execute(sql).fetchall()