/**
 * @file sessionChange.ts
 * @description `session_created` / `session_updated` matcher for live-refresh
 * callers that care about only a few session columns. A session row is
 * re-broadcast on nearly every hook (last activity, name, tokens…), so
 * matching the bare message types made every such frame refetch; this one
 * fires on a new session, or when the chosen key of a session actually
 * changed. Each call keeps its own memory of the keys it has seen.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

import type { Session, WSMessage } from "./types";

/** The columns that move a session between the active / waiting / archived counts. */
export const sessionStateKeyOf = (s: Partial<Session>): string =>
  `${s.status}:${s.awaiting_input_since ? 1 : 0}:${s.archived_at ? 1 : 0}`;

export function sessionChangeMatcher(
  keyOf: (s: Partial<Session>) => string = sessionStateKeyOf
): (msg: WSMessage) => boolean {
  const seen = new Map<string, string>();
  return (msg) => {
    if (msg.type !== "session_created" && msg.type !== "session_updated") return false;
    const s = msg.data as Partial<Session> | undefined;
    // A frame we cannot key is taken as a change: refetching is the safe side.
    if (!s || typeof s.id !== "string") return true;
    const key = keyOf(s);
    if (msg.type === "session_updated" && seen.get(s.id) === key) return false;
    seen.set(s.id, key);
    return true;
  };
}