from typing import Annotated

from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.database import get_db
from app.core.security import decode_access_token
from app.models import User

security = HTTPBearer()


async def get_current_user(
    credentials: Annotated[HTTPAuthorizationCredentials, Depends(security)],
    db: Annotated[AsyncSession, Depends(get_db)],
) -> User:
    token = credentials.credentials
    payload = decode_access_token(token)

    if payload is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid or expired token",
            headers={"WWW-Authenticate": "Bearer"},
        )

    user_id = payload.get("sub")
    if user_id is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid token payload",
        )

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

    if user is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="User not found",
        )

    return user


# Type aliases for cleaner dependency injection
CurrentUser = Annotated[User, Depends(get_current_user)]
DbSession = Annotated[AsyncSession, Depends(get_db)]