from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
from sqlalchemy.orm import DeclarativeBase
from app.core.config import settings

# Production: use DATABASE_URL (e.g. Supabase connection string)
# Local dev: construct from individual POSTGRES_* settings
if settings.DATABASE_URL:
    DATABASE_URL = settings.DATABASE_URL
    # Ensure asyncpg driver prefix
    if DATABASE_URL.startswith("postgres://"):
        DATABASE_URL = DATABASE_URL.replace("postgres://", "postgresql+asyncpg://", 1)
    elif DATABASE_URL.startswith("postgresql://"):
        DATABASE_URL = DATABASE_URL.replace("postgresql://", "postgresql+asyncpg://", 1)
else:
    DATABASE_URL = f"postgresql+asyncpg://{settings.POSTGRES_USER}:{settings.POSTGRES_PASSWORD}@{settings.POSTGRES_HOST}:{settings.POSTGRES_PORT}/{settings.POSTGRES_DB}"

engine = create_async_engine(DATABASE_URL, echo=False)
async_session_factory = async_sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)


class Base(DeclarativeBase):
    pass


async def get_db() -> AsyncSession:
    async with async_session_factory() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise
        finally:
            await session.close()