"""
轻量级服务端 Session 存储。

以客户端 IP + User-Agent 的哈希值作为 session key，
无需 cookie，无需前端改动。
每次 getScenes 写入，StartVoiceChat/StopVoiceChat 读取。
"""

import hashlib
from fastapi import Request

# { session_key: { scene_id: { RoomId, UserId, TaskId } } }
_store: dict[str, dict[str, dict]] = {}


def _key(request: Request) -> str:
    forwarded = request.headers.get("X-Forwarded-For")
    ip = (
        forwarded.split(",")[0].strip()
        if forwarded
        else (request.client.host if request.client else "unknown")
    )
    ua = request.headers.get("User-Agent", "")
    return hashlib.sha256(f"{ip}:{ua}".encode()).hexdigest()


def save_session(request: Request, scene_id: str, data: dict) -> None:
    key = _key(request)
    if key not in _store:
        _store[key] = {}
    _store[key][scene_id] = data


def load_session(request: Request, scene_id: str) -> dict:
    return _store.get(_key(request), {}).get(scene_id, {})