import { create } from "zustand";
import type { DeviceStatus, LedgerEvent, Occupancy } from "../api.js";

// CLIENT state for the live booth feed — deliberately small. Server data (the
// authoritative event list, occupancy totals) is owned by TanStack Query; this
// store holds only what Query shouldn't: the WS connection status, the latest
// pushed occupancy snapshot, and a rolling in-memory tail of recent events for the
// live ticker. Anything durable is re-fetched via Query. See lib/query.ts.

/** Connection state of the booth WebSocket, for a status indicator in the UI. */
export type WsStatus = "connecting" | "open" | "closed";

/** Cap the in-memory live feed so a long-running booth session can't grow it
 *  unbounded — the full history is always available via the /api/events query. */
const MAX_FEED = 200;

interface LiveState {
  status: WsStatus;
  /** Most recent occupancy pushed by the server (rides on every ledger event). */
  occupancy: Occupancy | null;
  /** Newest-first tail of recently pushed ledger events (for the live ticker). */
  feed: LedgerEvent[];
  /** Live device status keyed by device id (for the footer): set from the WS
   *  hello snapshot, then upserted per device on each device-status push. */
  devices: Record<string, DeviceStatus>;
  setStatus: (s: WsStatus) => void;
  setOccupancy: (o: Occupancy) => void;
  pushEvent: (e: LedgerEvent) => void;
  /** Replace the whole device-status set (WS hello / reconnect snapshot). */
  setDevices: (list: DeviceStatus[]) => void;
  /** Upsert one device's status (a device-status push). */
  upsertDevice: (d: DeviceStatus) => void;
  reset: () => void;
}

/** Index a device-status list by device id. */
function byId(list: DeviceStatus[]): Record<string, DeviceStatus> {
  const m: Record<string, DeviceStatus> = {};
  for (const d of list) m[d.deviceId] = d;
  return m;
}

export const useLiveStore = create<LiveState>((set) => ({
  status: "connecting",
  occupancy: null,
  feed: [],
  devices: {},
  setStatus: (status) => set({ status }),
  setOccupancy: (occupancy) => set({ occupancy }),
  pushEvent: (e) =>
    set((s) => ({
      // Newest first; de-dupe by id (a reconnect can replay) and cap the length.
      feed: s.feed.some((x) => x.id === e.id) ? s.feed : [e, ...s.feed].slice(0, MAX_FEED),
    })),
  setDevices: (list) => set({ devices: byId(list) }),
  upsertDevice: (d) => set((s) => ({ devices: { ...s.devices, [d.deviceId]: d } })),
  reset: () => set({ status: "connecting", occupancy: null, feed: [], devices: {} }),
}));