from collections.abc import AsyncGenerator

from datetime import datetime

from sqlalchemy import DateTime, func
from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column

from app.config import settings


class Base(DeclarativeBase):
    pass


class TimestampMixin:
    created_at: Mapped[datetime] = mapped_column(
        DateTime, server_default=func.now(), nullable=False
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime, server_default=func.now(), onupdate=func.now(), nullable=False
    )


engine = create_async_engine(
    settings.database_url,
    echo=settings.app_debug,
    future=True,
    pool_size=20,
    max_overflow=30,
    pool_recycle=3600,
    pool_pre_ping=True,
)
AsyncSessionLocal = async_sessionmaker(engine, expire_on_commit=False, class_=AsyncSession)


async def get_db() -> AsyncGenerator[AsyncSession, None]:
    async with AsyncSessionLocal() as session:
        yield session