import { decodeRailDeckRealtimeFrame, type RailDeckRealtimeSubscription } from '@raildeck/frontend-sdk/direct-integration';
import type { RailDeckDirectIntegrationClient } from '@raildeck/frontend-sdk/direct-integration';

type LayoutReader = Pick<RailDeckDirectIntegrationClient, 'currentState'>;

/**
 * Reads one authorised layout without issuing or retrying a command.
 * @param client - Configured integration client; the caller owns authentication.
 * @param accountId - Authorised account that owns the layout.
 * @param layoutId - Layout to observe within that account.
 * @param signal - Caller-owned cancellation signal.
 * @returns The SDK-decoded current-state response; errors propagate unchanged.
 */
export async function readLayoutState(
  client: LayoutReader,
  accountId: string,
  layoutId: string,
  signal: AbortSignal,
) {
  return client.currentState.getLayoutSnapshot(accountId, layoutId, {
    signal,
    timeoutMs: 15_000,
  });
}

/**
 * Decode an incoming frame before it reaches a projection or command coordinator.
 * @param frame - Untrusted text received by the caller's approved realtime transport.
 * @param subscription - The account or layout authorised for this connection.
 * @param receivedGeneration - Connection generation captured when receiving the frame.
 * @param activeGeneration - The caller's current connection generation.
 * @returns A decoded message or an explicit unsupported outcome; malformed frames throw.
 */
export function decodeIntegrationFrame(
  frame: string,
  subscription: RailDeckRealtimeSubscription,
  receivedGeneration: number,
  activeGeneration: number,
) {
  return decodeRailDeckRealtimeFrame(frame, {
    audience: 'direct-integration', subscription,
    receivedSocketGeneration: receivedGeneration,
    activeSocketGeneration: activeGeneration,
  });
}