from typing import Annotated, Dict, Optional
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import jwt, JWTError
from app.core.config import settings
from app.core.security import ALGORITHM
from sqlmodel import Session
from app.core.database import get_session
from app.models.user import User

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="api/auth/login", auto_error=False)

def get_token_payload(token: Annotated[str, Depends(oauth2_scheme)]) -> Dict:
    if not token:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Not authenticated",
            headers={"WWW-Authenticate": "Bearer"},
        )
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, settings.secret_key, algorithms=[ALGORITHM])
        return payload
    except JWTError:
        raise credentials_exception

async def get_current_user_token(token: Annotated[str, Depends(oauth2_scheme)]) -> Dict:
    return get_token_payload(token)

async def get_current_admin(token: Annotated[str, Depends(oauth2_scheme)]) -> bool:
    from app.models.user import UserRole
    payload = get_token_payload(token)
    role: str = payload.get("role")
    
    # Check for both "admin" and "ADMIN" for robust authorization
    if role not in ["admin", "ADMIN", UserRole.ADMIN]:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="The user doesn't have enough privileges",
        )
    return True

async def get_current_user(
    token: Annotated[str, Depends(oauth2_scheme)],
    session: Session = Depends(get_session)
) -> User:
    payload = get_token_payload(token)
    user_id = payload.get("sub")
    if not user_id:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Could not validate credentials",
        )
    user = session.get(User, user_id)
    if not user:
        raise HTTPException(status_code=404, detail="User not found")
    return user

async def get_current_user_optional(
    token: Optional[str] = Depends(oauth2_scheme),
    session: Session = Depends(get_session)
) -> Optional[User]:
    if not token:
        return None
    try:
        payload = jwt.decode(token, settings.secret_key, algorithms=[ALGORITHM])
        user_id = payload.get("sub")
        if not user_id:
            return None
        return session.get(User, user_id)
    except JWTError:
        return None