"""Database configuration and session management."""
from contextlib import asynccontextmanager
from typing import AsyncGenerator

from sqlalchemy.ext.asyncio import (
    AsyncSession,
    async_sessionmaker,
    create_async_engine,
)
from sqlalchemy.orm import DeclarativeBase

from app.core.config import settings

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

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


class Base(DeclarativeBase):
    """Base class for all SQLAlchemy models."""

    pass


async def get_db() -> AsyncGenerator[AsyncSession, None]:
    """
    Dependency function to get database session.

    Yields:
        AsyncSession: Database session.

    Example:
        @app.get("/users/")
        async def get_users(db: AsyncSession = Depends(get_db)):
            result = await db.execute(select(User))
            return result.scalars().all()
    """
    async with async_session_maker() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise
        finally:
            await session.close()


@asynccontextmanager
async def get_db_context() -> AsyncGenerator[AsyncSession, None]:
    """
    Context manager for database session.

    Yields:
        AsyncSession: Database session.

    Example:
        async with get_db_context() as db:
            await db.execute(insert(User).values(**user_data))
    """
    async with async_session_maker() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise
        finally:
            await session.close()


async def init_db() -> None:
    """Initialize database tables."""
    async with engine.begin() as conn:
        # Import all models here to ensure they're registered with Base
        from app.models import (  # noqa: F401
            album,
            artist,
            playlist,
            playlist_track,
            track,
            user,
        )

        # Create all tables
        await conn.run_sync(Base.metadata.create_all)


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