from typing import Optional
from sqlalchemy import create_engine
from sqlalchemy.engine import Engine

from actions.config.config import Config


class Firebird:
    _engine: Optional[Engine] = None

    @classmethod
    def get_engine(cls) -> Engine:
        # Obtem as configurações do arquivo JSON
        database = Config.get('database/firebird.json')

        # Cria a engine apenas uma vez
        if cls._engine is None:

            # DSN para o SQLAlchemy usando firebird-driver
            dsn = (
                f"firebird+firebird://{database.user}:"
                f"{database.password}@"
                f"{database.host}:"
                f"{database.port}/"
                f"{database.name}"
            )

            # Criação da engine SQLAlchemy
            cls._engine = create_engine(
                dsn,
                connect_args={"charset": database.charset},
                pool_pre_ping=bool(database.pool.pre_ping),
                pool_size=database.pool.size,
                max_overflow=database.pool.max_overflow,
            )

        return cls._engine

    @classmethod
    def dispose(cls):
        if cls._engine:
            cls._engine.dispose()
            cls._engine = None