"""Database setup: async engine, session factory, declarative base."""

from collections.abc import AsyncGenerator

from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
from sqlalchemy.orm import DeclarativeBase

from app.core.config import get_settings

settings = get_settings()

engine = create_async_engine(
    settings.database_url,
    echo=settings.log_level.upper() == "DEBUG",
    pool_pre_ping=True,
)

async_session_factory = async_sessionmaker(
    engine,
    class_=AsyncSession,
    expire_on_commit=False,
    autoflush=False,
)


class Base(DeclarativeBase):
    """Declarative base for all ORM models."""


async def get_db() -> AsyncGenerator[AsyncSession, None]:
    """FastAPI dependency yielding an async DB session."""
    async with async_session_factory() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise


async def init_db() -> None:
    """Create all tables (scaffold mode; Alembic migrations come later)."""
    # Import models so they register on the metadata
    from app import models  # noqa: F401

    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)