feat(dashboard): cache snapshot data and add credits activity analytics

tests/lib/credits-activity.test.ts

@@ -0,0 +1,129 @@
+import { describe, expect, it } from "vitest";
+
+import {
+  buildCreditsActivitySeries,
+  calculateUsageActivityDomain,
+  formatCredits,
+  prioritizeRecentCreditTransactions,
+} from "@/lib/credits-activity";
+
+type TestTransaction = {
+  _id: string;
+  _creationTime: number;
+  amount: number;
+  type: "subscription" | "topup" | "usage" | "reservation" | "refund";
+  status: "committed" | "reserved" | "released" | "failed";
+  description: string;
+};
+
+describe("credits activity helpers", () => {
+  it("formats credits as Cr label", () => {
+    expect(formatCredits(1234, "de-DE")).toBe("1.234 Cr");
+  });
+
+  it("prioritizes usage events ahead of non-usage items", () => {
+    const now = Date.UTC(2026, 3, 8, 10, 0, 0);
+    const tx: TestTransaction[] = [
+      {
+        _id: "topup-1",
+        _creationTime: now,
+        amount: 500,
+        type: "topup",
+        status: "committed",
+        description: "Top-up",
+      },
+      {
+        _id: "usage-1",
+        _creationTime: now - 60_000,
+        amount: -52,
+        type: "usage",
+        status: "committed",
+        description: "Image generation",
+      },
+      {
+        _id: "reservation-1",
+        _creationTime: now - 120_000,
+        amount: -52,
+        type: "reservation",
+        status: "reserved",
+        description: "Video reservation",
+      },
+    ];
+
+    const result = prioritizeRecentCreditTransactions(tx, 3);
+
+    expect(result.map((item) => item._id)).toEqual([
+      "usage-1",
+      "reservation-1",
+      "topup-1",
+    ]);
+  });
+
+  it("builds a daily activity series with usage and available line", () => {
+    const dayA = Date.UTC(2026, 3, 6, 8, 0, 0);
+    const dayB = Date.UTC(2026, 3, 7, 10, 0, 0);
+
+    const tx: TestTransaction[] = [
+      {
+        _id: "usage-a",
+        _creationTime: dayA,
+        amount: -40,
+        type: "usage",
+        status: "committed",
+        description: "Image",
+      },
+      {
+        _id: "reservation-b",
+        _creationTime: dayB,
+        amount: -30,
+        type: "reservation",
+        status: "reserved",
+        description: "Video queued",
+      },
+      {
+        _id: "usage-b",
+        _creationTime: dayB + 1_000,
+        amount: -60,
+        type: "usage",
+        status: "committed",
+        description: "Video done",
+      },
+    ];
+
+    const result = buildCreditsActivitySeries(tx, 320, "de-DE", 2);
+
+    expect(result).toEqual([
+      {
+        day: "06. Apr",
+        usage: 40,
+        activity: 40,
+        available: 320,
+      },
+      {
+        day: "07. Apr",
+        usage: 60,
+        activity: 90,
+        available: 320,
+      },
+    ]);
+  });
+
+  it("calculates a zoomed domain for low usage/activity values", () => {
+    const domain = calculateUsageActivityDomain([
+      {
+        day: "06. Apr",
+        usage: 4,
+        activity: 4,
+        available: 1200,
+      },
+      {
+        day: "07. Apr",
+        usage: 20,
+        activity: 20,
+        available: 1200,
+      },
+    ]);
+
+    expect(domain).toEqual([0, 24]);
+  });
+});