"""Session management — per-user data isolation."""

import hashlib
import os
from pathlib import Path
from contextvars import ContextVar

import config

USERS_DIR = config.DATA_DIR / "users"
_current_user_id: ContextVar[str] = ContextVar("current_user_id", default="default")


def set_current_user(user_id: str):
    if not user_id or user_id in ("None", "default", ""):
        user_id = hashlib.md5(os.urandom(8)).hexdigest()[:12]
    _current_user_id.set(str(user_id))


def get_current_user_id() -> str:
    return _current_user_id.get()


def get_user_dir(user_id: str = None) -> Path:
    uid = user_id or get_current_user_id()
    safe_id = hashlib.md5(uid.encode()).hexdigest()[:12]
    user_dir = USERS_DIR / safe_id
    user_dir.mkdir(parents=True, exist_ok=True)
    (user_dir / "saves").mkdir(exist_ok=True)
    return user_dir


def get_user_world_file(user_id: str = None) -> Path:
    return get_user_dir(user_id) / "world.json"


def get_user_saves_dir(user_id: str = None) -> Path:
    return get_user_dir(user_id) / "saves"


def get_user_active_slot_file(user_id: str = None) -> Path:
    return get_user_dir(user_id) / "active_slot.txt"


def ensure_session_id(sid) -> str:
    """Ensure we have a valid session ID. Generate one if missing."""
    if sid and isinstance(sid, str) and sid != "None" and len(sid) > 4:
        return sid
    return hashlib.md5(os.urandom(8)).hexdigest()[:12]