"""FastAPI dependencies."""

from __future__ import annotations

from typing import TYPE_CHECKING, Annotated

from fastapi import Depends, Request
from sqlalchemy.engine import Engine
from sqlalchemy.ext.asyncio import AsyncEngine, AsyncSession
from sqlalchemy.orm import Session

if TYPE_CHECKING:
    from collections.abc import AsyncIterator, Iterator


def get_engine(request: Request) -> Engine:
    """Get a synchronous database engine from app state."""
    return request.app.state.engine


def get_async_engine(request: Request) -> AsyncEngine:
    """Get an asynchronous database engine from app state."""
    return request.app.state.engine


def get_db(request: Request) -> Iterator[Session]:
    """Get database session from app state."""
    with Session(request.app.state.engine) as session:
        yield session


async def get_async_db(request: Request) -> AsyncIterator[AsyncSession]:
    """Get an async database session from app state.

    expire_on_commit=False keeps ORM attributes readable after commit without
    triggering implicit IO, which would raise under asyncio.
    """
    async with AsyncSession(request.app.state.engine, expire_on_commit=False) as session:
        yield session


AppEngine = Annotated[Engine, Depends(get_engine)]
AppAsyncEngine = Annotated[AsyncEngine, Depends(get_async_engine)]
DbSession = Annotated[Session, Depends(get_db)]
AsyncDbSession = Annotated[AsyncSession, Depends(get_async_db)]