refactor: dedupe shared helpers across ui/gateway/extensions

src/shared/usage-aggregates.ts

@@ -0,0 +1,63 @@
+type LatencyTotalsLike = {
+  count: number;
+  sum: number;
+  min: number;
+  max: number;
+  p95Max: number;
+};
+
+type DailyLatencyLike = {
+  date: string;
+  count: number;
+  sum: number;
+  min: number;
+  max: number;
+  p95Max: number;
+};
+
+type DailyLike = {
+  date: string;
+};
+
+export function buildUsageAggregateTail<
+  TTotals extends { totalCost: number },
+  TDaily extends DailyLike,
+  TModelDaily extends { date: string; cost: number },
+>(params: {
+  byChannelMap: Map<string, TTotals>;
+  latencyTotals: LatencyTotalsLike;
+  dailyLatencyMap: Map<string, DailyLatencyLike>;
+  modelDailyMap: Map<string, TModelDaily>;
+  dailyMap: Map<string, TDaily>;
+}) {
+  return {
+    byChannel: Array.from(params.byChannelMap.entries())
+      .map(([channel, totals]) => ({ channel, totals }))
+      .toSorted((a, b) => b.totals.totalCost - a.totals.totalCost),
+    latency:
+      params.latencyTotals.count > 0
+        ? {
+            count: params.latencyTotals.count,
+            avgMs: params.latencyTotals.sum / params.latencyTotals.count,
+            minMs:
+              params.latencyTotals.min === Number.POSITIVE_INFINITY ? 0 : params.latencyTotals.min,
+            maxMs: params.latencyTotals.max,
+            p95Ms: params.latencyTotals.p95Max,
+          }
+        : undefined,
+    dailyLatency: Array.from(params.dailyLatencyMap.values())
+      .map((entry) => ({
+        date: entry.date,
+        count: entry.count,
+        avgMs: entry.count ? entry.sum / entry.count : 0,
+        minMs: entry.min === Number.POSITIVE_INFINITY ? 0 : entry.min,
+        maxMs: entry.max,
+        p95Ms: entry.p95Max,
+      }))
+      .toSorted((a, b) => a.date.localeCompare(b.date)),
+    modelDaily: Array.from(params.modelDailyMap.values()).toSorted(
+      (a, b) => a.date.localeCompare(b.date) || b.cost - a.cost,
+    ),
+    daily: Array.from(params.dailyMap.values()).toSorted((a, b) => a.date.localeCompare(b.date)),
+  };
+}