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"""
Minimal session store for chat history + per-session data.
Features
- In-memory store with thread safety
- Create/get/update/delete sessions
- Append chat turns: ("user"| "bot", text)
- Optional TTL cleanup and max-history cap
- JSON persistence (save/load)
- Deterministic, dependency-free
Intended to interoperate with anon_bot and logged_in_bot:
- History shape: List[Tuple[str, str]] e.g., [("user","hi"), ("bot","hello")]
"""
from __future__ import annotations
from dataclasses import dataclass, asdict, field
from typing import Any, Dict, List, Optional, Tuple
from pathlib import Path
import time
import uuid
import json
import threading
History = List[Tuple[str, str]] # [("user","..."), ("bot","...")]
# -----------------------------
# Data model
# -----------------------------
@dataclass
class Session:
session_id: str
user_id: Optional[str] = None
created_at: float = field(default_factory=lambda: time.time())
updated_at: float = field(default_factory=lambda: time.time())
data: Dict[str, Any] = field(default_factory=dict) # arbitrary per-session state
history: History = field(default_factory=list) # chat transcripts
def to_dict(self) -> Dict[str, Any]:
d = asdict(self)
# dataclasses with tuples serialize fine, ensure tuples not lost if reloaded
return d
@staticmethod
def from_dict(d: Dict[str, Any]) -> "Session":
s = Session(
session_id=d["session_id"],
user_id=d.get("user_id"),
created_at=float(d.get("created_at", time.time())),
updated_at=float(d.get("updated_at", time.time())),
data=dict(d.get("data", {})),
history=[(str(who), str(text)) for who, text in d.get("history", [])],
)
return s
# -----------------------------
# Store
# -----------------------------
class SessionStore:
"""
Thread-safe in-memory session registry with optional TTL and persistence.
"""
def __init__(
self,
ttl_seconds: Optional[int] = 60 * 60, # 1 hour default; set None to disable
max_history: int = 200, # cap messages per session
) -> None:
self._ttl = ttl_seconds
self._max_history = max_history
self._lock = threading.RLock()
self._sessions: Dict[str, Session] = {}
# ---- id helpers ----
@staticmethod
def new_id() -> str:
return uuid.uuid4().hex
# ---- CRUD ----
def create(self, user_id: Optional[str] = None, session_id: Optional[str] = None) -> Session:
with self._lock:
sid = session_id or self.new_id()
s = Session(session_id=sid, user_id=user_id)
self._sessions[sid] = s
return s
def get(self, session_id: str, create_if_missing: bool = False, user_id: Optional[str] = None) -> Optional[Session]:
with self._lock:
s = self._sessions.get(session_id)
if s is None and create_if_missing:
s = self.create(user_id=user_id, session_id=session_id)
return s
def delete(self, session_id: str) -> bool:
with self._lock:
return self._sessions.pop(session_id, None) is not None
def all_ids(self) -> List[str]:
with self._lock:
return list(self._sessions.keys())
# ---- housekeeping ----
def _expired(self, s: Session) -> bool:
if self._ttl is None:
return False
return (time.time() - s.updated_at) > self._ttl
def sweep(self) -> int:
"""
Remove expired sessions. Returns number removed.
"""
with self._lock:
dead = [sid for sid, s in self._sessions.items() if self._expired(s)]
for sid in dead:
self._sessions.pop(sid, None)
return len(dead)
# ---- history ops ----
def append_user(self, session_id: str, text: str) -> Session:
return self._append(session_id, "user", text)
def append_bot(self, session_id: str, text: str) -> Session:
return self._append(session_id, "bot", text)
def _append(self, session_id: str, who: str, text: str) -> Session:
with self._lock:
s = self._sessions.get(session_id)
if s is None:
s = self.create(session_id=session_id)
s.history.append((who, text))
if self._max_history and len(s.history) > self._max_history:
# Keep most recent N entries
s.history = s.history[-self._max_history :]
s.updated_at = time.time()
return s
def get_history(self, session_id: str) -> History:
with self._lock:
s = self._sessions.get(session_id)
return list(s.history) if s else []
def clear_history(self, session_id: str) -> bool:
with self._lock:
s = self._sessions.get(session_id)
if not s:
return False
s.history.clear()
s.updated_at = time.time()
return True
# ---- key/value per-session data ----
def set(self, session_id: str, key: str, value: Any) -> Session:
with self._lock:
s = self._sessions.get(session_id)
if s is None:
s = self.create(session_id=session_id)
s.data[key] = value
s.updated_at = time.time()
return s
def get_value(self, session_id: str, key: str, default: Any = None) -> Any:
with self._lock:
s = self._sessions.get(session_id)
if not s:
return default
return s.data.get(key, default)
def data_dict(self, session_id: str) -> Dict[str, Any]:
with self._lock:
s = self._sessions.get(session_id)
return dict(s.data) if s else {}
# ---- persistence ----
def save(self, path: str | Path) -> None:
p = Path(path)
p.parent.mkdir(parents=True, exist_ok=True)
with self._lock:
payload = {
"ttl_seconds": self._ttl,
"max_history": self._max_history,
"saved_at": time.time(),
"sessions": {sid: s.to_dict() for sid, s in self._sessions.items()},
}
p.write_text(json.dumps(payload, ensure_ascii=False), encoding="utf-8")
@classmethod
def load(cls, path: str | Path) -> "SessionStore":
p = Path(path)
if not p.is_file():
return cls()
data = json.loads(p.read_text(encoding="utf-8"))
store = cls(
ttl_seconds=data.get("ttl_seconds"),
max_history=int(data.get("max_history", 200)),
)
sessions = data.get("sessions", {})
with store._lock:
for sid, sd in sessions.items():
store._sessions[sid] = Session.from_dict(sd)
return store
# -----------------------------
# Module-level singleton (optional)
# -----------------------------
_default_store: Optional[SessionStore] = None
def get_store() -> SessionStore:
global _default_store
if _default_store is None:
_default_store = SessionStore()
return _default_store
def new_session(user_id: Optional[str] = None) -> Session:
return get_store().create(user_id=user_id)
def append_user(session_id: str, text: str) -> Session:
return get_store().append_user(session_id, text)
def append_bot(session_id: str, text: str) -> Session:
return get_store().append_bot(session_id, text)
def history(session_id: str) -> History:
return get_store().get_history(session_id)
def set_value(session_id: str, key: str, value: Any) -> Session:
return get_store().set(session_id, key, value)
def get_value(session_id: str, key: str, default: Any = None) -> Any:
return get_store().get_value(session_id, key, default)
def sweep() -> int:
return get_store().sweep()
@classmethod
def default(cls) -> "SessionStore":
"""
Convenience singleton used by tests (SessionStore.default()).
Delegates to the module-level get_store() to share the same instance.
"""
# get_store is defined at module scope below; resolved at call time.
from .sessions import get_store # type: ignore
return get_store()
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