from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
from sqlalchemy.orm import DeclarativeBase
from sqlalchemy import event, text
from app.config import get_settings

settings = get_settings()

engine = create_async_engine(
    settings.DATABASE_URL,
    echo=settings.DEBUG,
    pool_size=20,
    max_overflow=10,
    pool_pre_ping=True,
)

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


class Base(DeclarativeBase):
    pass


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


async def init_db():
    """Initialize database extensions and create tables."""
    async with engine.begin() as conn:
        # Enable pgvector extension for RAG embeddings
        await conn.execute(text("CREATE EXTENSION IF NOT EXISTS vector"))
        await conn.execute(text("CREATE EXTENSION IF NOT EXISTS pg_trgm"))
        # Create all tables
        await conn.run_sync(Base.metadata.create_all)