import inspect
from functools import wraps
from typing import Callable, Any, Tuple, Optional
from fastapi import Request
from fastapi.responses import RedirectResponse
from passlib.context import CryptContext

# Accept Argon2 (preferred) and legacy bcrypt; new hashes will be Argon2.
pwd_context = CryptContext(
    schemes=["argon2", "bcrypt"],
    deprecated="auto",
)

def hash_password(p: str) -> str:
    return pwd_context.hash(p)

def verify_password(p: str, hashed: str) -> bool:
    return pwd_context.verify(p, hashed)

def verify_and_update_password(p: str, hashed: str) -> Tuple[bool, Optional[str]]:
    """
    Returns (verified, new_hash). If verified is True and new_hash is not None,
    caller should persist the new_hash (Argon2) to upgrade legacy bcrypt.
    """
    try:
        return pwd_context.verify_and_update(p, hashed)
    except Exception:
        return False, None

def _extract_request(args, kwargs) -> Optional[Request]:
    req: Optional[Request] = kwargs.get("request")
    if isinstance(req, Request):
        return req
    for a in args:
        if isinstance(a, Request):
            return a
    return None

def login_required(endpoint: Callable[..., Any]):
    """
    Decorator that supports both sync and async FastAPI endpoints.
    Redirects to /login when no session is present.
    """
    if inspect.iscoroutinefunction(endpoint):
        @wraps(endpoint)
        async def async_wrapper(*args, **kwargs):
            request = _extract_request(args, kwargs)
            if not request or not request.session.get("user_id"):
                return RedirectResponse(url="/login", status_code=303)
            return await endpoint(*args, **kwargs)
        return async_wrapper
    else:
        @wraps(endpoint)
        def sync_wrapper(*args, **kwargs):
            request = _extract_request(args, kwargs)
            if not request or not request.session.get("user_id"):
                return RedirectResponse(url="/login", status_code=303)
            return endpoint(*args, **kwargs)
        return sync_wrapper

def get_current_user(request: Request):
    return {"id": request.session.get("user_id"), "username": request.session.get("username")}