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


class Base(DeclarativeBase):
    pass


async_engine = create_async_engine(
    settings.DATABASE_URL,
    pool_size=20,
    max_overflow=40,
    pool_pre_ping=True,
    pool_recycle=3600,
    echo=False,
)

AsyncSessionLocal = async_sessionmaker(
    async_engine,
    class_=AsyncSession,
    expire_on_commit=False,
)


async def init_db():
    async with async_engine.begin() as conn:
        from models import Base as MBase
        await conn.run_sync(MBase.metadata.create_all)

    await _run_migrations()


async def _run_migrations():
    async with async_engine.begin() as conn:
        await conn.execute(text(
            "ALTER TABLE flow_definitions ADD COLUMN IF NOT EXISTS published_version_id UUID REFERENCES flow_versions(id)"
        ))
        await conn.execute(text(
            "ALTER TABLE flow_definitions ADD COLUMN IF NOT EXISTS draft_definition_json JSONB"
        ))


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