export type FrontRpcCode = "VALIDATION" | "NETWORK" | "INTERNAL";

export type FrontResponse<T = unknown> = {
  ok: boolean;
  code: FrontRpcCode | string;
  layer: "front";
  message: string;
  context?: Record<string, unknown>;
  data?: T | null;
  errors?: Record<string, string> | string[] | null;
};

export function buildFrontError(
  message: string,
  code: FrontRpcCode = "VALIDATION",
  context?: Record<string, unknown>,
  errors?: Record<string, string> | string[] | null,
): FrontResponse {
  return {
    ok: false,
    code,
    layer: "front",
    message,
    context,
    data: null,
    errors: errors ?? null,
  };
}

export function buildFrontNetworkError(method: string, path: string): FrontResponse {
  return buildFrontError(
    `No se pudo conectar con el servidor en ${method} ${path} — verifique su conexión`,
    "NETWORK",
    { route: `${method} ${path}` },
  );
}

export function isApiEnvelope(value: unknown): value is {
  ok: boolean;
  code: string;
  status?: number;
  layer: string;
  message: string;
  data?: unknown;
} {
  return !!value && typeof value === "object"
    && "ok" in value && "message" in value && "layer" in value;
}

/** Normaliza respuestas RPC `{ ok, data, message }` al shape plano que esperan las pantallas. */
export function unwrapApiPayload<T>(body: unknown): T {
  if (!isApiEnvelope(body)) return body as T;
  const env = body;
  const data = env.data;
  const spread = data && typeof data === "object" && !Array.isArray(data)
    ? data as Record<string, unknown>
    : {};
  return {
    ...spread,
    data,
    ok: env.ok,
    code: env.code,
    message: env.message,
    status: env.status,
    layer: env.layer,
  } as T;
}

/** Muestra el mensaje detallado de la API o front sin reescribirlo. */
export function displayErrorMessage(value: unknown, fallback = "Ocurrió un error"): string {
  if (isApiEnvelope(value)) return value.message;
  if (value && typeof value === "object" && "message" in value) {
    return String((value as { message: unknown }).message);
  }
  if (value && typeof value === "object" && "error" in value) {
    return String((value as { error: unknown }).error);
  }
  return fallback;
}