"""
Database client for AI Service.
[AC-AISVC-11] PostgreSQL database with SQLModel for multi-tenant data isolation.
"""

import logging
from typing import AsyncGenerator

from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
from sqlalchemy.pool import NullPool
from sqlmodel import SQLModel

from app.core.config import get_settings

logger = logging.getLogger(__name__)

settings = get_settings()

engine = create_async_engine(
    settings.database_url,
    pool_size=settings.database_pool_size,
    max_overflow=settings.database_max_overflow,
    echo=settings.debug,
    pool_pre_ping=True,
)

async_session_maker = async_sessionmaker(
    engine,
    class_=AsyncSession,
    expire_on_commit=False,
    autocommit=False,
    autoflush=False,
)


async def init_db() -> None:
    """
    [AC-AISVC-11] Initialize database tables.
    Creates all tables defined in SQLModel metadata.
    """
    async with engine.begin() as conn:
        await conn.run_sync(SQLModel.metadata.create_all)
    logger.info("[AC-AISVC-11] Database tables initialized")


async def close_db() -> None:
    """
    Close database connections.
    """
    await engine.dispose()
    logger.info("Database connections closed")


async def get_session() -> AsyncGenerator[AsyncSession, None]:
    """
    [AC-AISVC-11] Dependency injection for database session.
    Ensures proper session lifecycle management.
    """
    async with async_session_maker() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise
        finally:
            await session.close()