from functools import lru_cache

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.database import get_db
from app.models.user import User
from app.services.api_key_manager import APIKeyManager
from app.services.auth import verify_token

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/v1/auth/login")


@lru_cache(maxsize=1)
def get_key_manager() -> APIKeyManager:
    manager = APIKeyManager()
    manager.load_env_keys()
    return manager


async def get_current_user(
    token: str = Depends(oauth2_scheme),
    db: AsyncSession = Depends(get_db),
) -> User:
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )

    try:
        payload = verify_token(token)
        user_id: str | None = payload.get("sub")
        if user_id is None:
            raise credentials_exception
    except (JWTError, ValueError):
        raise credentials_exception

    stmt = select(User).where(User.id == user_id)
    result = await db.execute(stmt)
    user = result.scalar_one_or_none()

    if user is None:
        raise credentials_exception

    return user