"""PostgreSQL 연결 — SQLAlchemy async engine + session factory"""

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

from core.config import settings

engine = create_async_engine(
    settings.database_url,
    echo=False,
    pool_size=10,
    max_overflow=20,
)

async_session = async_sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)


class Base(DeclarativeBase):
    pass


async def init_db():
    """DB 연결 확인 (스키마는 migrations/로 관리)"""
    async with engine.begin() as conn:
        # 연결 테스트
        await conn.execute(
            __import__("sqlalchemy").text("SELECT 1")
        )


async def get_session() -> AsyncSession:
    """FastAPI Depends용 세션 제공"""
    async with async_session() as session:
        yield session