import { type LlamaSwapConfig } from "./util";

export interface UsageStats {
  totalRequests: number;
  totalInputTokens: number;
  totalOutputTokens: number;
  genP95: number;
}

export function parseStats(json: unknown): UsageStats | null {
  if (!json || typeof json !== "object") return null;
  const obj = json as Record<string, unknown>;
  const genHist = (obj.gen_histogram ?? {}) as Record<string, unknown>;
  const num = (v: unknown): number => (typeof v === "number" && Number.isFinite(v) ? v : 0);
  return {
    totalRequests: num(obj.total_requests),
    totalInputTokens: num(obj.total_input_tokens),
    totalOutputTokens: num(obj.total_output_tokens),
    genP95: num(genHist.p95),
  };
}

export async function fetchStats(cfg: LlamaSwapConfig, modelId: string): Promise<UsageStats | null> {
  const query = modelId === "all" ? "" : `?model=${encodeURIComponent(modelId)}`;
  const headers: Record<string, string> = {};
  if (cfg.apiKey) headers["Authorization"] = `Bearer ${cfg.apiKey}`;
  const res = await fetch(`${cfg.baseUrl}/api/metrics/stats${query}`, {
    headers,
    signal: AbortSignal.timeout(5000),
  });
  if (!res.ok) return null;
  return parseStats(await res.json());
}