import type { AssistantMessageEventStream, Usage } from "@earendil-works/pi-ai";
import { abortError } from "./remote-types.js";

export async function collectProviderUsage(stream: AssistantMessageEventStream, signal: AbortSignal): Promise<Usage> {
  let usage: Usage | undefined;
  for await (const event of stream) {
    if (signal.aborted) throw abortError();
    if (event.type === "error") {
      throw new Error(event.error.errorMessage ?? "Responses compaction request failed");
    }
    if (event.type === "done") usage = event.message.usage;
  }
  if (signal.aborted) throw abortError();
  if (!usage) throw new Error("Responses provider stream ended without completion usage");
  return usage;
}