feat: add backend proxy for Horizon transaction history

Author: code-with-flex

backend/src/horizon-rate-limit.service.ts

@@ -0,0 +1,277 @@
+/**
+ * Horizon proxy integration tests.
+ *
+ * Uses mocked fetch and mocked Redis — no real Horizon credentials required.
+ * Covers: field filtering, rate limiting, 429 response, cache hit, address validation.
+ */
+
+import { Test, TestingModule } from "@nestjs/testing";
+import { INestApplication, HttpStatus } from "@nestjs/common";
+import * as request from "supertest";
+import { ConfigModule } from "@nestjs/config";
+import { HorizonModule } from "../horizon.module";
+import { RedisService } from "../../cache/redis.service";
+
+// ── Fixtures ──────────────────────────────────────────────────────────────────
+
+const VALID_ACCOUNT = "GBCPNZ6S7RK5N4BX6HBXBCX7P5QNBOJZFGDWBZBXCLK5T6KHWOPTLR3I";
+
+const MOCK_HORIZON_RESPONSE = {
+  _links: {
+    self: {
+      href: "https://horizon-testnet.stellar.org/accounts/G.../operations?limit=20",
+    },
+    next: {
+      href: "https://horizon-testnet.stellar.org/accounts/G.../operations?cursor=abc123&limit=20",
+    },
+  },
+  _embedded: {
+    records: [
+      {
+        id: "1234567890",
+        paging_token: "token-1",
+        type: "payment",
+        type_int: 1,
+        created_at: "2024-01-15T10:00:00Z",
+        transaction_hash: "aabbcc",
+        transaction_successful: true,
+        source_account: VALID_ACCOUNT,
+        asset_type: "native",
+        amount: "100.0000000",
+        from: VALID_ACCOUNT,
+        to: "GXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
+        // Fields that must be stripped:
+        _links: { self: { href: "..." } },
+        offer_id: "99",
+        sponsor: "GSOME_SPONSOR",
+        funder: "GFUNDER",
+      },
+      {
+        // DEX operation — must be filtered out
+        id: "999",
+        paging_token: "token-dex",
+        type: "manage_sell_offer",
+        type_int: 3,
+        created_at: "2024-01-15T09:00:00Z",
+        transaction_hash: "dex-hash",
+        transaction_successful: true,
+        source_account: VALID_ACCOUNT,
+        offer_id: "42",
+        price: "1.5",
+      },
+    ],
+  },
+};
+
+// ── Redis mock ────────────────────────────────────────────────────────────────
+
+function createRedisMock() {
+  const store = new Map<string, string>();
+  return {
+    get: jest.fn(async <T>(key: string): Promise<T | null> => {
+      const val = store.get(key);
+      return val ? (JSON.parse(val) as T) : null;
+    }),
+    set: jest.fn(async (key: string, value: unknown) => {
+      store.set(key, JSON.stringify(value));
+    }),
+    del: jest.fn(async (key: string) => {
+      store.delete(key);
+    }),
+    delPattern: jest.fn(),
+    getClient: jest.fn(() => ({
+      multi: jest.fn(() => ({
+        zremrangebyscore: jest.fn().mockReturnThis(),
+        zcard: jest.fn().mockReturnThis(),
+        zadd: jest.fn().mockReturnThis(),
+        expire: jest.fn().mockReturnThis(),
+        exec: jest.fn().mockResolvedValue([
+          [null, 1],
+          [null, 0], // zcard returns 0 — under limit
+          [null, 1],
+          [null, 1],
+        ]),
+      })),
+      zremrangebyscore: jest.fn(),
+    })),
+    ping: jest.fn(async () => true),
+    onModuleDestroy: jest.fn(),
+  };
+}
+
+// ── Test setup ────────────────────────────────────────────────────────────────
+
+describe("HorizonController (integration)", () => {
+  let app: INestApplication;
+  let redisMock: ReturnType<typeof createRedisMock>;
+  let fetchSpy: jest.SpyInstance;
+
+  beforeEach(async () => {
+    redisMock = createRedisMock();
+
+    // Mock global fetch — no real Horizon call made
+    fetchSpy = jest.spyOn(global, "fetch").mockResolvedValue({
+      ok: true,
+      status: 200,
+      json: async () => MOCK_HORIZON_RESPONSE,
+    } as Response);
+
+    // Override STELLAR_NETWORK env so network config does not throw
+    process.env.STELLAR_NETWORK = "testnet";
+    process.env.STELLAR_NETWORK_PASSPHRASE = "Test SDF Network ; September 2015";
+
+    const moduleRef: TestingModule = await Test.createTestingModule({
+      imports: [
+        ConfigModule.forRoot({
+          isGlobal: true,
+          ignoreEnvFile: true,
+          load: [
+            () => ({
+              REDIS_URL: "redis://mock:6379",
+              STELLAR_NETWORK: "testnet",
+              STELLAR_NETWORK_PASSPHRASE: "Test SDF Network ; September 2015",
+              SOROBAN_RPC_URL: "https://soroban-testnet.stellar.org",
+              CONTRACT_ID: "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM",
+            }),
+          ],
+        }),
+        HorizonModule,
+      ],
+    })
+      .overrideProvider(RedisService)
+      .useValue(redisMock)
+      .compile();
+
+    app = moduleRef.createNestApplication();
+    app.setGlobalPrefix("api");
+    await app.init();
+  });
+
+  afterEach(async () => {
+    jest.restoreAllMocks();
+    await app.close();
+  });
+
+  // ── Field filtering ───────────────────────────────────────────────────────
+
+  it("returns only payment operations and strips internal Horizon fields", async () => {
+    const res = await request(app.getHttpServer())
+      .get("/api/horizon/transactions")
+      .query({ account: VALID_ACCOUNT });
+
+    expect(res.status).toBe(HttpStatus.OK);
+    expect(res.body.records).toHaveLength(1); // manage_sell_offer filtered out
+    const record = res.body.records[0];
+
+    // Required fields present
+    expect(record).toMatchObject({
+      id: "1234567890",
+      type: "payment",
+      amount: "100.0000000",
+      transaction_successful: true,
+    });
+
+    // Stripped fields must not be present
+    expect(record).not.toHaveProperty("_links");
+    expect(record).not.toHaveProperty("offer_id");
+    expect(record).not.toHaveProperty("sponsor");
+    expect(record).not.toHaveProperty("funder");
+  });
+
+  it("exposes next_cursor when Horizon provides a next link", async () => {
+    const res = await request(app.getHttpServer())
+      .get("/api/horizon/transactions")
+      .query({ account: VALID_ACCOUNT });
+
+    expect(res.status).toBe(HttpStatus.OK);
+    expect(res.body.next_cursor).toBe("abc123");
+  });
+
+  // ── Response headers must not leak API keys ───────────────────────────────
+
+  it("does not expose Authorization or Horizon API key in response headers", async () => {
+    const res = await request(app.getHttpServer())
+      .get("/api/horizon/transactions")
+      .query({ account: VALID_ACCOUNT });
+
+    expect(res.headers).not.toHaveProperty("authorization");
+    expect(res.headers).not.toHaveProperty("x-horizon-api-key");
+  });
+
+  // ── Address validation ────────────────────────────────────────────────────
+
+  it("returns 400 for a missing account parameter", async () => {
+    const res = await request(app.getHttpServer()).get("/api/horizon/transactions");
+    expect(res.status).toBe(HttpStatus.BAD_REQUEST);
+  });
+
+  it("returns 400 for an invalid Stellar address", async () => {
+    const res = await request(app.getHttpServer())
+      .get("/api/horizon/transactions")
+      .query({ account: "not-a-stellar-address" });
+
+    expect(res.status).toBe(HttpStatus.BAD_REQUEST);
+  });
+
+  // ── Cache hit ─────────────────────────────────────────────────────────────
+
+  it("serves from cache on second identical request without calling Horizon again", async () => {
+    await request(app.getHttpServer())
+      .get("/api/horizon/transactions")
+      .query({ account: VALID_ACCOUNT });
+
+    // Seed the cache with what the first request stored
+    const cachedValue = { records: [], next_cursor: undefined };
+    redisMock.get.mockResolvedValueOnce(cachedValue);
+
+    await request(app.getHttpServer())
+      .get("/api/horizon/transactions")
+      .query({ account: VALID_ACCOUNT });
+
+    // fetch should only have been called once (the second served from cache)
+    expect(fetchSpy).toHaveBeenCalledTimes(1);
+  });
+
+  // ── Rate limiting ─────────────────────────────────────────────────────────
+
+  it("returns 429 with Retry-After header when rate limit is exceeded", async () => {
+    // Make zcard return a count at the limit
+    redisMock.getClient.mockReturnValue({
+      multi: jest.fn(() => ({
+        zremrangebyscore: jest.fn().mockReturnThis(),
+        zcard: jest.fn().mockReturnThis(),
+        zadd: jest.fn().mockReturnThis(),
+        expire: jest.fn().mockReturnThis(),
+        exec: jest.fn().mockResolvedValue([
+          [null, 1],
+          [null, 30], // at limit
+          [null, 1],
+          [null, 1],
+        ]),
+      })),
+      zremrangebyscore: jest.fn(),
+    });
+
+    const res = await request(app.getHttpServer())
+      .get("/api/horizon/transactions")
+      .query({ account: VALID_ACCOUNT });
+
+    expect(res.status).toBe(429);
+    expect(res.headers).toHaveProperty("retry-after");
+    expect(res.body.error).toBe("Too Many Requests");
+  });
+
+  // ── Horizon upstream failure ──────────────────────────────────────────────
+
+  it("returns 502 when Horizon is unreachable", async () => {
+    fetchSpy.mockRejectedValueOnce(new Error("ECONNREFUSED"));
+
+    const res = await request(app.getHttpServer())
+      .get("/api/horizon/transactions")
+      .query({ account: VALID_ACCOUNT });
+
+    expect(res.status).toBe(HttpStatus.BAD_GATEWAY);
+    // Error body must not contain any API key
+    expect(JSON.stringify(res.body)).not.toContain("Bearer");
+  });
+});

backend/src/horizon/__tests__/horizon.integration.spec.ts

@@ -0,0 +1,68 @@
+/**
+ * Horizon Transaction DTOs
+ *
+ * Fields forwarded from Horizon and why:
+ *
+ * FORWARDED:
+ *   id                  — unique operation identifier; used by frontend for deduplication
+ *   paging_token        — cursor for paginated fetches
+ *   type                — operation type string (e.g. "payment", "change_trust")
+ *   type_int            — numeric type; easier for frontend switch/case
+ *   created_at          — ISO timestamp of the ledger close containing this operation
+ *   transaction_hash    — links operation to its parent transaction; shown in explorer links
+ *   transaction_successful — guards UI from displaying failed operations as completed
+ *   source_account      — sender address
+ *   asset_type          — "native" | "credit_alphanum4" | "credit_alphanum12"
+ *   asset_code          — token ticker (undefined for XLM)
+ *   asset_issuer        — issuer address (undefined for XLM)
+ *   amount              — transfer amount as string (Stellar uses string to avoid float loss)
+ *   from / to           — payment parties
+ *
+ * STRIPPED:
+ *   _links              — Horizon HAL links; internal navigation not needed by frontend
+ *   records[].links     — same reason
+ *   funder / account    — create_account-specific; not used in payment history view
+ *   starting_balance    — create_account-specific
+ *   offer_id            — DEX offer internals; not relevant to policy-payment history
+ *   price / price_r     — DEX pricing fields
+ *   buying_* / selling_* — DEX asset pair fields
+ *   claimable_balance_id — claimable-balance internals
+ *   sponsor             — reserve-sponsoring; not displayed in current UI
+ *   bump_to             — bump_sequence internals
+ *   authorize*          — change_trust flag fields
+ *   limit               — change_trust limit; not shown
+ *   set_flags* / clear_flags* — account flags
+ *   home_domain / thresholds / signers / inflation_dest — account meta changes
+ *
+ * HORIZON FINALITY LAG:
+ *   Stellar closes a ledger approximately every 5 seconds. The `created_at` field
+ *   reflects ledger close time, not submission time. Operations are final once
+ *   included in a closed ledger — there is no probabilistic finality.
+ *   However, Horizon ingestion may lag 1–3 ledgers (~5–15 seconds) behind the
+ *   network tip. The frontend should show a "transactions may take up to 15 seconds
+ *   to appear" notice and avoid treating a missing transaction as definitively
+ *   failed until at least 30 seconds have elapsed.
+ */
+
+export interface HorizonOperationRecord {
+  id: string;
+  paging_token: string;
+  type: string;
+  type_int: number;
+  created_at: string;
+  transaction_hash: string;
+  transaction_successful: boolean;
+  source_account: string;
+  // Payment / path-payment fields (optional — only present on relevant types)
+  asset_type?: string;
+  asset_code?: string;
+  asset_issuer?: string;
+  amount?: string;
+  from?: string;
+  to?: string;
+}
+
+export interface HorizonTransactionResponse {
+  records: HorizonOperationRecord[];
+  next_cursor?: string;
+}