"""Database configuration and session management."""

from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
from sqlalchemy.orm import declarative_base
from sqlalchemy.pool import NullPool
from typing import AsyncGenerator

from app.core.config import settings

# Create async engine
engine = create_async_engine(
    settings.DATABASE_URL,
    pool_size=settings.DB_POOL_SIZE,
    max_overflow=settings.DB_MAX_OVERFLOW,
    echo=False,
    future=True,
)

# Create async session factory
AsyncSessionLocal = async_sessionmaker(
    engine,
    class_=AsyncSession,
    expire_on_commit=False,
    autocommit=False,
    autoflush=False,
)

# Create declarative base
Base = declarative_base()


async def get_db() -> AsyncGenerator[AsyncSession, None]:
    """
    Dependency for getting async database sessions.

    Yields:
        AsyncSession: Database session
    """
    async with AsyncSessionLocal() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise
        finally:
            await session.close()


async def init_db():
    """Initialize database tables."""
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)


async def close_db():
    """Close database connections."""
    await engine.dispose()