feat(routes-f): add weighted featured channel rotation endpoint and t…

app/api/routes-f/featured-channel/__tests__/featured-channel.test.ts

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+import { NextRequest } from "next/server";
+import { GET, POST } from "../route";
+import {
+  CANDIDATES,
+  selectByWeight,
+  resetRotation,
+  getCurrentRotationId,
+} from "../helpers";
+
+const BASE_URL = "http://localhost/api/routes-f/featured-channel";
+
+function makeGet() {
+  return new NextRequest(BASE_URL, { method: "GET" });
+}
+
+function makePost() {
+  return new NextRequest(`${BASE_URL}/next`, { method: "POST" });
+}
+
+beforeEach(() => {
+  resetRotation();
+});
+
+describe("GET /api/routes-f/featured-channel", () => {
+  it("returns 200 with featured_creator, rotation_id, rotates_at", async () => {
+    const res = await GET();
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body).toHaveProperty("featured_creator");
+    expect(body).toHaveProperty("rotation_id");
+    expect(body).toHaveProperty("rotates_at");
+  });
+
+  it("featured_creator has expected fields", async () => {
+    const res = await GET();
+    const { featured_creator } = await res.json();
+    expect(featured_creator).toHaveProperty("id");
+    expect(featured_creator).toHaveProperty("name");
+    expect(featured_creator).toHaveProperty("wallet_address");
+    expect(featured_creator).toHaveProperty("avatar_url");
+    expect(featured_creator).toHaveProperty("category");
+    expect(featured_creator).toHaveProperty("followers");
+    expect(typeof featured_creator.is_live).toBe("boolean");
+    expect(typeof featured_creator.weight).toBe("number");
+  });
+
+  it("returns the same creator for the same rotation_id (determinism)", async () => {
+    const res1 = await GET();
+    const res2 = await GET();
+    const body1 = await res1.json();
+    const body2 = await res2.json();
+    expect(body1.featured_creator.id).toBe(body2.featured_creator.id);
+    expect(body1.rotation_id).toBe(body2.rotation_id);
+  });
+
+  it("rotates_at is a valid future ISO date", async () => {
+    const res = await GET();
+    const { rotates_at } = await res.json();
+    const date = new Date(rotates_at);
+    expect(date.getTime()).toBeGreaterThan(Date.now());
+  });
+});
+
+describe("POST /api/routes-f/featured-channel (advance rotation)", () => {
+  it("returns 200 with new rotation_id and rotates_at", async () => {
+    const res = await POST();
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body).toHaveProperty("rotation_id");
+    expect(body).toHaveProperty("rotates_at");
+  });
+
+  it("advances rotation_id on each POST", async () => {
+    const r1 = await POST();
+    const r2 = await POST();
+    const b1 = await r1.json();
+    const b2 = await r2.json();
+    expect(b1.rotation_id).not.toBe(b2.rotation_id);
+  });
+
+  it("GET after POST returns a different rotation_id", async () => {
+    const getRes1 = await GET();
+    const { rotation_id: rid1 } = await getRes1.json();
+
+    await POST();
+
+    const getRes2 = await GET();
+    const { rotation_id: rid2 } = await getRes2.json();
+    expect(rid1).not.toBe(rid2);
+  });
+});
+
+describe("selectByWeight determinism", () => {
+  it("same rotation_id always produces the same creator", () => {
+    const a = selectByWeight(CANDIDATES, "test-seed-42");
+    const b = selectByWeight(CANDIDATES, "test-seed-42");
+    expect(a.id).toBe(b.id);
+  });
+
+  it("different rotation_ids can produce different creators", () => {
+    const ids = Array.from({ length: 50 }, (_, i) => `seed-${i}`);
+    const selected = new Set(ids.map(id => selectByWeight(CANDIDATES, id).id));
+    // With 50 different seeds and 20 candidates, we expect multiple distinct picks
+    expect(selected.size).toBeGreaterThan(1);
+  });
+
+  it("higher-weight creators are selected more frequently", () => {
+    const counts: Record<string, number> = {};
+    const trials = 1000;
+    for (let i = 0; i < trials; i++) {
+      const c = selectByWeight(CANDIDATES, `distribution-${i}`);
+      counts[c.id] = (counts[c.id] || 0) + 1;
+    }
+
+    // GamingGuru (weight 15) should appear more often than LunarLens (weight 1)
+    const highWeight = counts["fc-003"] ?? 0;
+    const lowWeight = counts["fc-012"] ?? 0;
+    expect(highWeight).toBeGreaterThan(lowWeight);
+  });
+
+  it("all candidates can potentially be selected", () => {
+    const selected = new Set<string>();
+    for (let i = 0; i < 5000; i++) {
+      const c = selectByWeight(CANDIDATES, `coverage-${i}`);
+      selected.add(c.id);
+    }
+    // With 5000 trials, all 20 candidates should appear at least once
+    expect(selected.size).toBe(CANDIDATES.length);
+  });
+});

app/api/routes-f/featured-channel/helpers.ts

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+import type { FeaturedCreator } from "./types";
+
+// ~20 candidate creators with weights for featured rotation
+export const CANDIDATES: FeaturedCreator[] = [
+  {
+    id: "fc-001",
+    name: "CryptoKing",
+    wallet_address: "GBZX...CK01",
+    avatar_url: "https://streamfi.xyz/avatars/crypto-king.webp",
+    category: "DeFi & Finance",
+    followers: 14200,
+    is_live: true,
+    weight: 10,
+  },
+  {
+    id: "fc-002",
+    name: "ArtByLena",
+    wallet_address: "GCXY...LN02",
+    avatar_url: "https://streamfi.xyz/avatars/art-by-lena.webp",
+    category: "Digital Art",
+    followers: 8300,
+    is_live: false,
+    weight: 7,
+  },
+  {
+    id: "fc-003",
+    name: "GamingGuru",
+    wallet_address: "GDAB...GG03",
+    avatar_url: "https://streamfi.xyz/avatars/gaming-guru.webp",
+    category: "Gaming",
+    followers: 32000,
+    is_live: true,
+    weight: 15,
+  },
+  {
+    id: "fc-004",
+    name: "MusicMaven",
+    wallet_address: "GDEF...MM04",
+    avatar_url: "https://streamfi.xyz/avatars/music-maven.webp",
+    category: "Music & Production",
+    followers: 5600,
+    is_live: false,
+    weight: 5,
+  },
+  {
+    id: "fc-005",
+    name: "DevDojo",
+    wallet_address: "GHIJ...DD05",
+    avatar_url: "https://streamfi.xyz/avatars/dev-dojo.webp",
+    category: "Dev & Programming",
+    followers: 11200,
+    is_live: true,
+    weight: 9,
+  },
+  {
+    id: "fc-006",
+    name: "StellarSam",
+    wallet_address: "GKLM...SS06",
+    avatar_url: "https://streamfi.xyz/avatars/stellar-sam.webp",
+    category: "DeFi & Finance",
+    followers: 2300,
+    is_live: false,
+    weight: 3,
+  },
+  {
+    id: "fc-007",
+    name: "PixelPaula",
+    wallet_address: "GNOP...PP07",
+    avatar_url: "https://streamfi.xyz/avatars/pixel-paula.webp",
+    category: "Digital Art",
+    followers: 1100,
+    is_live: false,
+    weight: 2,
+  },
+  {
+    id: "fc-008",
+    name: "CodeWithKai",
+    wallet_address: "GQRS...CK08",
+    avatar_url: "https://streamfi.xyz/avatars/code-with-kai.webp",
+    category: "Dev & Programming",
+    followers: 4500,
+    is_live: true,
+    weight: 6,
+  },
+  {
+    id: "fc-009",
+    name: "BeatsByNova",
+    wallet_address: "GTUV...BN09",
+    avatar_url: "https://streamfi.xyz/avatars/beats-by-nova.webp",
+    category: "Music & Production",
+    followers: 800,
+    is_live: false,
+    weight: 2,
+  },
+  {
+    id: "fc-010",
+    name: "CryptoChess",
+    wallet_address: "GWXY...CC10",
+    avatar_url: "https://streamfi.xyz/avatars/crypto-chess.webp",
+    category: "Gaming",
+    followers: 1900,
+    is_live: false,
+    weight: 3,
+  },
+  {
+    id: "fc-011",
+    name: "ZenYogi",
+    wallet_address: "GABC...ZY11",
+    avatar_url: "https://streamfi.xyz/avatars/zen-yogi.webp",
+    category: "Wellness & Lifestyle",
+    followers: 3400,
+    is_live: true,
+    weight: 4,
+  },
+  {
+    id: "fc-012",
+    name: "LunarLens",
+    wallet_address: "GDEF...LL12",
+    avatar_url: "https://streamfi.xyz/avatars/lunar-lens.webp",
+    category: "Photography",
+    followers: 700,
+    is_live: false,
+    weight: 1,
+  },
+  {
+    id: "fc-013",
+    name: "SorobanSally",
+    wallet_address: "GHIJ...SS13",
+    avatar_url: "https://streamfi.xyz/avatars/soroban-sally.webp",
+    category: "DeFi & Finance",
+    followers: 8800,
+    is_live: false,
+    weight: 8,
+  },
+  {
+    id: "fc-014",
+    name: "NeonNinja",
+    wallet_address: "GKLM...NN14",
+    avatar_url: "https://streamfi.xyz/avatars/neon-ninja.webp",
+    category: "Gaming",
+    followers: 21000,
+    is_live: true,
+    weight: 12,
+  },
+  {
+    id: "fc-015",
+    name: "ChillBeats",
+    wallet_address: "GNOP...CB15",
+    avatar_url: "https://streamfi.xyz/avatars/chill-beats.webp",
+    category: "Music & Production",
+    followers: 6200,
+    is_live: false,
+    weight: 5,
+  },
+  {
+    id: "fc-016",
+    name: "BlockBrush",
+    wallet_address: "GQRS...BB16",
+    avatar_url: "https://streamfi.xyz/avatars/block-brush.webp",
+    category: "Digital Art",
+    followers: 4100,
+    is_live: false,
+    weight: 4,
+  },
+  {
+    id: "fc-017",
+    name: "QuantumQoder",
+    wallet_address: "GTUV...QQ17",
+    avatar_url: "https://streamfi.xyz/avatars/quantum-qoder.webp",
+    category: "Dev & Programming",
+    followers: 15800,
+    is_live: true,
+    weight: 11,
+  },
+  {
+    id: "fc-018",
+    name: "VoxelViv",
+    wallet_address: "GWXY...VV18",
+    avatar_url: "https://streamfi.xyz/avatars/voxel-viv.webp",
+    category: "Gaming",
+    followers: 9400,
+    is_live: false,
+    weight: 7,
+  },
+  {
+    id: "fc-019",
+    name: "TokenTara",
+    wallet_address: "GABC...TT19",
+    avatar_url: "https://streamfi.xyz/avatars/token-tara.webp",
+    category: "DeFi & Finance",
+    followers: 12600,
+    is_live: true,
+    weight: 9,
+  },
+  {
+    id: "fc-020",
+    name: "RhythmRex",
+    wallet_address: "GDEF...RR20",
+    avatar_url: "https://streamfi.xyz/avatars/rhythm-rex.webp",
+    category: "Music & Production",
+    followers: 3200,
+    is_live: false,
+    weight: 3,
+  },
+];
+
+// Deterministic seeded PRNG (mulberry32)
+function mulberry32(seed: number): () => number {
+  return () => {
+    seed |= 0;
+    seed = (seed + 0x6d2b79f5) | 0;
+    let t = Math.imul(seed ^ (seed >>> 15), 1 | seed);
+    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
+    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
+  };
+}
+
+// Convert a rotation_id string to a numeric seed
+function rotationSeed(rotationId: string): number {
+  let hash = 0;
+  for (let i = 0; i < rotationId.length; i++) {
+    hash = ((hash << 5) - hash + rotationId.charCodeAt(i)) | 0;
+  }
+  return hash;
+}
+
+// Pick a creator using weighted random selection, deterministic by rotation_id
+export function selectByWeight(
+  candidates: FeaturedCreator[],
+  rotationId: string
+): FeaturedCreator {
+  const rng = mulberry32(rotationSeed(rotationId));
+  const totalWeight = candidates.reduce((sum, c) => sum + c.weight, 0);
+  const roll = rng() * totalWeight;
+
+  let cumulative = 0;
+  for (const c of candidates) {
+    cumulative += c.weight;
+    if (roll < cumulative) return c;
+  }
+  return candidates[candidates.length - 1];
+}
+
+// In-memory rotation state
+let currentRotationIndex = 0;
+
+export function getCurrentRotationId(): string {
+  return `rot-${currentRotationIndex}`;
+}
+
+export function advanceRotation(): string {
+  currentRotationIndex++;
+  return getCurrentRotationId();
+}
+
+export function resetRotation(): void {
+  currentRotationIndex = 0;
+}
+
+const ROTATION_INTERVAL_MS = 30 * 60 * 1000; // 30 minutes
+
+export function getRotatesAt(): string {
+  return new Date(Date.now() + ROTATION_INTERVAL_MS).toISOString();
+}