/**
 * @file usePanePresence.ts
 * @description Who has each of a workspace's panes open (server mode, workspace
 * sharing phase 4): `GET /api/lanes/:id/presence` once, then every
 * `pane_presence` frame for that workspace, and a re-read on a WebSocket
 * reconnect (frames missed while away are never replayed). Local mode has
 * one user and reads nothing. Returns `{runId: [{id, name}]}`.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

import { useEffect, useState } from "react";
import { api } from "../lib/api";
import { eventBus } from "../lib/eventBus";
import { usePermissions } from "../components/AuthGate";

export type PanePeople = Record<string, { id: number; name: string }[]>;

export function usePanePresence(laneId: number | null | undefined): PanePeople {
  const { local } = usePermissions();
  const [panes, setPanes] = useState<PanePeople>({});
  useEffect(() => {
    setPanes({});
    if (local || laneId == null) return;
    let alive = true;
    const load = () =>
      Promise.resolve()
        .then(() => api.lanes.presence(laneId))
        .then((r) => alive && setPanes(r.panes))
        .catch(() => {
          /* presence is a nicety: no list, no chips */
        });
    void load();
    const offMsg = eventBus.subscribe((msg) => {
      if (msg.type !== "pane_presence") return;
      const d = msg.data as { laneId?: number; runId?: string; users?: PanePeople[string] };
      if (d.laneId !== laneId || !d.runId) return;
      setPanes((prev) => {
        const next = { ...prev };
        if (d.users?.length) next[d.runId!] = d.users;
        else delete next[d.runId!];
        return next;
      });
    });
    const offConn = eventBus.onConnection((up) => {
      if (up) void load();
    });
    return () => {
      alive = false;
      offMsg();
      offConn();
    };
  }, [laneId, local]);
  return panes;
}