import { broadcastQueryClient } from "@tanstack/query-broadcast-client-experimental";
import type { QueryClient } from "@tanstack/react-query";

/** Prefix for same-origin BroadcastChannel names (suffixed with authenticated user id). */
export const QUERY_BROADCAST_CHANNEL_PREFIX = "seahaven-admin-query";

let unsubscribe: (() => void) | null = null;
let activeUserId: string | number | null = null;

/** Builds the account-scoped channel name for cross-tab QueryClient sync. */
export function queryBroadcastChannelForUser(userId: string | number): string {
  return `${QUERY_BROADCAST_CHANNEL_PREFIX}:${String(userId)}`;
}

function disposeBroadcast(): void {
  unsubscribe?.();
  unsubscribe = null;
  activeUserId = null;
}

function canUseBroadcast(): boolean {
  return typeof window !== "undefined" && import.meta.env.MODE !== "test";
}

/**
 * Starts (or switches) account-scoped QueryClient broadcast.
 * Disposes any prior subscription; clears the cache when the authenticated user changes.
 * No-op for the BroadcastChannel outside the browser and during Vitest runs.
 */
export function startQueryBroadcast(queryClient: QueryClient, userId: string | number): void {
  if (activeUserId === userId) {
    return;
  }

  const previousUserId = activeUserId;
  disposeBroadcast();

  if (previousUserId != null && previousUserId !== userId) {
    queryClient.clear();
  }

  activeUserId = userId;

  if (!canUseBroadcast()) {
    return;
  }

  unsubscribe = broadcastQueryClient({
    queryClient,
    broadcastChannel: queryBroadcastChannelForUser(userId),
  });
}

/**
 * Tears down the broadcaster and clears the entire QueryClient cache (logout / 401).
 */
export function stopQueryBroadcast(queryClient: QueryClient): void {
  disposeBroadcast();
  queryClient.clear();
}