"""
Database connection and session management.
Async SQLAlchemy 2.0 with asyncpg driver.
"""

import os
from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession, async_sessionmaker
from sqlalchemy import text

DATABASE_URL = os.getenv(
    "DATABASE_URL",
    "postgresql+asyncpg://postgres:postgres@lifeos-db:5432/lifeos_dev"
)

engine = create_async_engine(
    DATABASE_URL,
    echo=os.getenv("ENVIRONMENT") == "development",
    pool_size=5,
    max_overflow=10,
    pool_pre_ping=True,
)

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


async def get_db():
    """FastAPI dependency: yields an async database session."""
    async with async_session_factory() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise
        finally:
            await session.close()


async def check_db():
    """Health check: verify database connectivity."""
    async with async_session_factory() as session:
        result = await session.execute(text("SELECT 1"))
        return result.scalar() == 1