"""
线程安全的共享状态总线，用于三模型之间的松耦合通信。
"""
import threading
import time
from collections import deque
from datetime import datetime
from typing import Any, Dict, List, Optional


class SharedState:
    def __init__(self, history_size: int = 10):
        self._lock = threading.RLock()
        self._history_size = history_size
        self._channels: Dict[str, _Channel] = {}

    def publish(self, channel: str, data: dict) -> None:
        with self._lock:
            if channel not in self._channels:
                self._channels[channel] = _Channel(self._history_size)
            self._channels[channel].write(data)

    def read(self, channel: str, max_age_seconds: Optional[float] = None) -> Optional[dict]:
        with self._lock:
            ch = self._channels.get(channel)
            if ch is None:
                return None
            return ch.read(max_age_seconds)

    def read_history(self, channel: str, limit: int = 10) -> List[dict]:
        with self._lock:
            ch = self._channels.get(channel)
            if ch is None:
                return []
            return list(ch.history)


class _Channel:
    __slots__ = ("latest", "updated_at", "history")

    def __init__(self, history_size: int):
        self.latest: Optional[dict] = None
        self.updated_at: Optional[float] = None
        self.history: deque = deque(maxlen=history_size)

    def write(self, data: dict) -> None:
        self.latest = data
        self.updated_at = time.time()
        self.history.append({"data": data, "ts": self.updated_at})

    def read(self, max_age_seconds: Optional[float] = None) -> Optional[dict]:
        if self.latest is None:
            return None
        if max_age_seconds is not None and self.updated_at is not None:
            if time.time() - self.updated_at > max_age_seconds:
                return None
        return self.latest