from collections.abc import AsyncGenerator
from contextlib import asynccontextmanager
from sqlalchemy import Engine
from sqlalchemy.ext.asyncio import (
    AsyncConnection,
    AsyncEngine,
    AsyncSession,
    async_sessionmaker,
    create_async_engine,
)
from sqlmodel import create_engine, SQLModel


from ..settings import get_settings

settings = get_settings()


async def _get_async_engine() -> AsyncEngine:
    return create_async_engine(
            f"postgresql+asyncpg://{settings.db.username}:{settings.db.password}@localhost/{settings.db.db_name}",
            future=True,
        )


async def get_session() -> AsyncGenerator[AsyncSession, None]:
    """
    Initialize a database session and return it.

    Use this when interacting via the ORM.
    """
    engine = await _get_async_engine()
    async_session = async_sessionmaker(bind=engine, expire_on_commit=False)
    async with async_session() as session:
        yield session


@asynccontextmanager
async def get_connection() -> AsyncGenerator[AsyncConnection, None]:
    """
    Initialize a database connection and return it.

    Only use this when you need to execute raw SQL queries.
    """
    engine = await _get_async_engine()
    async with engine.connect() as connection:
        yield connection

    await engine.dispose()


def _get_engine() -> Engine:
    return create_engine(
        f"postgresql+pg8000://{settings.db.username}:{settings.db.password}@localhost/{settings.db.db_name}"
    )


def create_db_and_tables():
    engine = _get_engine()
    SQLModel.metadata.create_all(engine)

    # TODO: add seeding