from typing import AsyncGenerator
from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
from .database import AsyncSessionLocal
from .models.user import User
from .services.auth import decode_token

bearer_scheme = HTTPBearer(auto_error=False)


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


async def get_current_user(
    credentials: HTTPAuthorizationCredentials | None = Depends(bearer_scheme),
    db: AsyncSession = Depends(get_db),
) -> User:
    if not credentials:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Not authenticated")

    user_id = decode_token(credentials.credentials)
    if not user_id:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token")

    result = await db.execute(select(User).where(User.id == user_id, User.is_active == True))
    user = result.scalar_one_or_none()
    if not user:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="User not found")
    return user


async def require_admin(current_user: User = Depends(get_current_user)) -> User:
    if not current_user.is_admin:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Admin required")
    return current_user