from typing import Annotated, AsyncGenerator

from fastapi import Depends, HTTPException, status
from pydantic import ValidationError
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.security import decode_access_token, oauth2_scheme
from app.db.session import SessionLocal
from app.schemas.user import TokenPayload


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


async def get_current_user(token: Annotated[str, Depends(oauth2_scheme)]) -> TokenPayload:
    payload = decode_access_token(token)
    try:
        return TokenPayload(**payload)
    except ValidationError as exc:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Could not validate credentials",
            headers={"WWW-Authenticate": "Bearer"},
        ) from exc