feat: add usage stats parsing and fetching from /api/metrics/stats

src/lib/stats.ts

@@ -0,0 +1,33 @@
+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());
+}