Refactor Study Desk application structure

src/services/activityService.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it } from "vitest";
+import { summarizeActivityBuckets, summarizeActivityRows } from "./activityService";
+
+describe("summarizeActivityRows", () => {
+  it("keeps a 53-week display while preserving a longer current streak", () => {
+    const now = new Date("2026-08-07T18:00:00.000Z");
+    const activities = Array.from({ length: 400 }, (_, age) =>
+      Array.from({ length: 20 }, () => ({
+        type: "FLASHCARD",
+        occurredAt: new Date(now.getTime() - age * 24 * 60 * 60 * 1000),
+      }))
+    ).flat();
+    const summary = summarizeActivityRows(activities, now);
+    expect(summary.days).toHaveLength(371);
+    expect(summary.currentStreak).toBe(400);
+    expect(summary.days.filter((day) => day.date <= summary.today).at(-1)?.date).toBe(summary.today);
+  });
+
+  it("preserves counts and long streaks from database-aggregated daily buckets", () => {
+    const now = new Date("2026-08-07T18:00:00.000Z");
+    const buckets = Array.from({ length: 400 }, (_, age) => ({
+      date: new Date(now.getTime() - 7 * 60 * 60 * 1000 - age * 86_400_000)
+        .toISOString()
+        .slice(0, 10),
+      type: "FLASHCARD",
+      count: 20,
+    }));
+    const summary = summarizeActivityBuckets(buckets, now);
+    expect(summary.currentStreak).toBe(400);
+    expect(summary.days).toHaveLength(371);
+  });
+});