import type {ResponseMetadata} from "./conversation-types";

export function responseMetadata(providerId: string, model: string, startedAt: number, outputTokens: number | undefined | null): ResponseMetadata {
  const durationMs = Math.max(1, Math.round(performance.now() - startedAt));
  const normalizedTokens = typeof outputTokens === "number" && Number.isFinite(outputTokens) && outputTokens >= 0
    ? Math.round(outputTokens)
    : null;
  const tokensPerSecond = normalizedTokens === null
    ? null
    : Math.round((normalizedTokens / (durationMs / 1000)) * 10) / 10;
  return {providerId, model, durationMs, outputTokens: normalizedTokens, tokensPerSecond};
}