AI scaffolded NodeJS version of the App.

app-new/backend/package.json

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+{
+  "name": "azure-image-chooser-backend",
+  "version": "0.1.0",
+  "private": true,
+  "type": "commonjs",
+  "scripts": {
+    "build": "tsc -p tsconfig.json",
+    "dev": "tsx watch src/server.ts",
+    "start": "node ../../dist/backend/server.js",
+    "test": "vitest run"
+  },
+  "dependencies": {
+    "@azure/arm-compute": "^23.3.0",
+    "@azure/identity": "^4.13.1",
+    "cors": "^2.8.5",
+    "dotenv": "^17.2.3",
+    "express": "^5.2.1",
+    "nunjucks": "^3.2.4",
+    "zod": "^4.3.6"
+  },
+  "devDependencies": {
+    "@types/cors": "^2.8.19",
+    "@types/express": "^5.0.3",
+    "@types/nunjucks": "^3.2.6",
+    "@types/node": "^24.9.1",
+    "typescript": "^6.0.3",
+    "tsx": "^4.20.6",
+    "vitest": "^3.2.4"
+  }
+}

app-new/backend/src/azure-service.ts

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+import { ComputeManagementClient } from "@azure/arm-compute";
+import { DefaultAzureCredential } from "@azure/identity";
+import { MemoryCache } from "./cache";
+import { sortImageVersionsIfSemantic } from "./version";
+import type { LocationOption } from "./types";
+
+const CACHE_TTL_MS = 5 * 60 * 1000;
+
+export class AzureImageService {
+  private readonly credential = new DefaultAzureCredential();
+
+  private readonly computeClient: ComputeManagementClient;
+
+  private readonly cache = new MemoryCache();
+
+  public constructor(private readonly subscriptionId: string) {
+    this.computeClient = new ComputeManagementClient(this.credential, subscriptionId);
+  }
+
+  public async getLocations(): Promise<LocationOption[]> {
+    const cacheKey = "locations";
+    const cached = this.cache.get<LocationOption[]>(cacheKey);
+    if (cached) {
+      return cached;
+    }
+
+    const token = await this.credential.getToken("https://management.azure.com/.default");
+    const url = `https://management.azure.com/subscriptions/${this.subscriptionId}/locations?api-version=2022-12-01`;
+    const response = await fetch(url, {
+      headers: {
+        Authorization: `Bearer ${token?.token ?? ""}`
+      }
+    });
+
+    const payload = (await response.json()) as { value?: Array<{ name?: string; displayName?: string; metadata?: { regionType?: string } }> };
+
+    const locations = (payload.value ?? [])
+      .filter((loc) => loc.metadata?.regionType === "Physical" && Boolean(loc.name))
+      .map((loc) => ({
+        name: loc.name as string,
+        displayName: loc.displayName ?? (loc.name as string)
+      }));
+
+    locations.sort((a, b) => a.name.localeCompare(b.name));
+    this.cache.set(cacheKey, locations, CACHE_TTL_MS);
+    return locations;
+  }
+
+  public async getPublishers(location: string): Promise<string[]> {
+    const cacheKey = `publishers:${location}`;
+    const cached = this.cache.get<string[]>(cacheKey);
+    if (cached) {
+      return cached;
+    }
+
+    const response = await this.computeClient.virtualMachineImages.listPublishers(location);
+    const publishers = this.extractNames(response);
+
+    this.cache.set(cacheKey, publishers, CACHE_TTL_MS);
+    return publishers;
+  }
+
+  public async getOffers(location: string, publisher: string): Promise<string[]> {
+    const cacheKey = `offers:${location}:${publisher}`;
+    const cached = this.cache.get<string[]>(cacheKey);
+    if (cached) {
+      return cached;
+    }
+
+    const response = await this.computeClient.virtualMachineImages.listOffers(location, publisher);
+    const offers = this.extractNames(response);
+
+    this.cache.set(cacheKey, offers, CACHE_TTL_MS);
+    return offers;
+  }
+
+  public async getSkus(location: string, publisher: string, offer: string): Promise<string[]> {
+    const cacheKey = `skus:${location}:${publisher}:${offer}`;
+    const cached = this.cache.get<string[]>(cacheKey);
+    if (cached) {
+      return cached;
+    }
+
+    const response = await this.computeClient.virtualMachineImages.listSkus(location, publisher, offer);
+    const skus = this.extractNames(response);
+
+    this.cache.set(cacheKey, skus, CACHE_TTL_MS);
+    return skus;
+  }
+
+  public async getVersions(location: string, publisher: string, offer: string, sku: string): Promise<string[]> {
+    const cacheKey = `versions:${location}:${publisher}:${offer}:${sku}`;
+    const cached = this.cache.get<string[]>(cacheKey);
+    if (cached) {
+      return cached;
+    }
+
+    const response = await this.computeClient.virtualMachineImages.list(location, publisher, offer, sku);
+    const versions = this.extractNames(response);
+
+    const sorted = sortImageVersionsIfSemantic(versions);
+    this.cache.set(cacheKey, sorted, CACHE_TTL_MS);
+    return sorted;
+  }
+
+  private extractNames(source: unknown): string[] {
+    const items = Array.isArray(source)
+      ? source
+      : typeof source === "object" && source !== null && "value" in source && Array.isArray((source as { value?: unknown }).value)
+        ? ((source as { value: unknown[] }).value as unknown[])
+        : [];
+
+    return items
+      .map((item) => (typeof item === "object" && item !== null && "name" in item ? (item as { name?: string }).name : undefined))
+      .filter((value): value is string => Boolean(value));
+  }
+}

app-new/backend/src/cache.ts

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+type CacheEntry<T> = {
+  value: T;
+  expiresAt: number;
+};
+
+export class MemoryCache {
+  private readonly store = new Map<string, CacheEntry<unknown>>();
+
+  public get<T>(key: string): T | undefined {
+    const hit = this.store.get(key);
+    if (!hit) {
+      return undefined;
+    }
+
+    if (Date.now() >= hit.expiresAt) {
+      this.store.delete(key);
+      return undefined;
+    }
+
+    return hit.value as T;
+  }
+
+  public set<T>(key: string, value: T, ttlMs: number): void {
+    this.store.set(key, {
+      value,
+      expiresAt: Date.now() + ttlMs
+    });
+  }
+}

app-new/backend/src/server.ts

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+import { existsSync } from "node:fs";
+import { join } from "node:path";
+import cors from "cors";
+import "dotenv/config";
+import express from "express";
+import { z } from "zod";
+import { AzureImageService } from "./azure-service";
+import { TemplateService } from "./template-service";
+
+const queryLocation = z.object({ location: z.string().min(1) });
+const queryOffer = z.object({ location: z.string().min(1), publisher: z.string().min(1) });
+const querySku = z.object({ location: z.string().min(1), publisher: z.string().min(1), offer: z.string().min(1) });
+const queryVersion = z.object({ location: z.string().min(1), publisher: z.string().min(1), offer: z.string().min(1), sku: z.string().min(1) });
+
+const renderBody = z.object({
+  templateFile: z.string().min(1),
+  selection: z.object({
+    location: z.string().min(1),
+    publisher: z.string().min(1),
+    offer: z.string().min(1),
+    sku: z.string().min(1),
+    version: z.string().min(1)
+  })
+});
+
+const makeApp = () => {
+  const app = express();
+  const port = Number.parseInt(process.env.PORT ?? "3000", 10);
+  const subscriptionId = process.env.AZURE_SUBSCRIPTION_ID;
+
+  app.use(cors());
+  app.use(express.json());
+
+  if (!subscriptionId) {
+    app.get("/api/health", (_req, res) => {
+      res.status(500).json({
+        status: "error",
+        message: "Missing AZURE_SUBSCRIPTION_ID"
+      });
+    });
+
+    return { app, port };
+  }
+
+  const azure = new AzureImageService(subscriptionId);
+  const templates = new TemplateService();
+
+  app.get("/api/health", (_req, res) => {
+    res.json({ status: "ok" });
+  });
+
+  app.get("/api/locations", async (_req, res, next) => {
+    try {
+      res.json(await azure.getLocations());
+    } catch (error) {
+      next(error);
+    }
+  });
+
+  app.get("/api/publishers", async (req, res, next) => {
+    try {
+      const { location } = queryLocation.parse(req.query);
+      res.json(await azure.getPublishers(location));
+    } catch (error) {
+      next(error);
+    }
+  });
+
+  app.get("/api/offers", async (req, res, next) => {
+    try {
+      const { location, publisher } = queryOffer.parse(req.query);
+      res.json(await azure.getOffers(location, publisher));
+    } catch (error) {
+      next(error);
+    }
+  });
+
+  app.get("/api/skus", async (req, res, next) => {
+    try {
+      const { location, publisher, offer } = querySku.parse(req.query);
+      res.json(await azure.getSkus(location, publisher, offer));
+    } catch (error) {
+      next(error);
+    }
+  });
+
+  app.get("/api/versions", async (req, res, next) => {
+    try {
+      const { location, publisher, offer, sku } = queryVersion.parse(req.query);
+      res.json(await azure.getVersions(location, publisher, offer, sku));
+    } catch (error) {
+      next(error);
+    }
+  });
+
+  app.get("/api/templates", (_req, res) => {
+    res.json(templates.getTemplates());
+  });
+
+  app.post("/api/render", (req, res, next) => {
+    try {
+      const payload = renderBody.parse(req.body);
+      const rendered = templates.render(payload.templateFile, payload.selection);
+      res.json({ rendered });
+    } catch (error) {
+      next(error);
+    }
+  });
+
+  app.get("/api/sku-export", async (req, res, next) => {
+    try {
+      const { location, publisher, offer } = querySku.parse(req.query);
+      const skus = await azure.getSkus(location, publisher, offer);
+      res.json({ rendered: templates.buildSkuExport(skus) });
+    } catch (error) {
+      next(error);
+    }
+  });
+
+  app.use((err: unknown, _req: express.Request, res: express.Response, _next: express.NextFunction) => {
+    if (err instanceof z.ZodError) {
+      res.status(400).json({ message: "Invalid request", issues: err.issues });
+      return;
+    }
+
+    const message = err instanceof Error ? err.message : "Unexpected error";
+    res.status(500).json({ message });
+  });
+
+  const frontendRoot = join(process.cwd(), "dist/frontend");
+  if (existsSync(frontendRoot)) {
+    app.use(express.static(frontendRoot));
+    app.get(/^(?!\/api).*/, (_req, res) => {
+      res.sendFile(join(frontendRoot, "index.html"));
+    });
+  }
+
+  return { app, port };
+};
+
+if (require.main === module) {
+  const { app, port } = makeApp();
+  app.listen(port, () => {
+    // eslint-disable-next-line no-console
+    console.log(`azure-image-chooser listening on ${port}`);
+  });
+}
+
+export { makeApp };

app-new/backend/src/template-service.ts

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+import { readFileSync } from "node:fs";
+import { join } from "node:path";
+import nunjucks from "nunjucks";
+import type { ImageSelection, UsageTemplate } from "./types";
+
+const findAppRoot = (): string => {
+  // Supports running from src/backend (dev) and dist/backend (compiled).
+  const devPath = join(__dirname, "../../../app");
+  const buildPath = join(__dirname, "../../app");
+  try {
+    readFileSync(join(devPath, "templates.json"), "utf8");
+    return devPath;
+  } catch {
+    return buildPath;
+  }
+};
+
+export class TemplateService {
+  private readonly appRoot = findAppRoot();
+
+  private readonly env = nunjucks.configure(join(this.appRoot, "templates"), {
+    autoescape: false,
+    noCache: true
+  });
+
+  private readonly templates: UsageTemplate[] = JSON.parse(
+    readFileSync(join(this.appRoot, "templates.json"), "utf8")
+  ) as UsageTemplate[];
+
+  public getTemplates(): UsageTemplate[] {
+    return this.templates;
+  }
+
+  public render(templateFile: string, selection: ImageSelection): string {
+    return this.env.render(templateFile, selection);
+  }
+
+  public buildSkuExport(skus: string[]): string {
+    return `[\n${skus.map((sku) => `\t\"${sku}\"`).join(",\n")}\n]`;
+  }
+}

app-new/backend/src/types.ts

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+export type LocationOption = {
+  name: string;
+  displayName: string;
+};
+
+export type UsageTemplate = {
+  label: string;
+  language: string;
+  file: string;
+};
+
+export type ImageSelection = {
+  location: string;
+  publisher: string;
+  offer: string;
+  sku: string;
+  version: string;
+};

app-new/backend/src/version.ts

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+const SEMVER_PATTERN = /^[0-9]+\.[0-9]+\.[0-9]+$/;
+
+const semverSortKey = (value: string): number[] => value.split(".").map((part) => Number.parseInt(part, 10));
+
+export const sortImageVersionsIfSemantic = (versions: string[]): string[] => {
+  if (!versions.every((value) => SEMVER_PATTERN.test(value))) {
+    return versions;
+  }
+
+  return [...versions].sort((a, b) => {
+    const aParts = semverSortKey(a);
+    const bParts = semverSortKey(b);
+
+    for (let i = 0; i < aParts.length; i += 1) {
+      if (aParts[i] !== bParts[i]) {
+        return aParts[i] - bParts[i];
+      }
+    }
+
+    return 0;
+  });
+};

app-new/backend/test/version.test.ts

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+import { describe, expect, it } from "vitest";
+import { sortImageVersionsIfSemantic } from "../src/version";
+
+describe("sortImageVersionsIfSemantic", () => {
+  it("sorts only semantic versions", () => {
+    const sorted = sortImageVersionsIfSemantic(["1.10.0", "1.2.0", "2.0.0"]);
+    expect(sorted).toEqual(["1.2.0", "1.10.0", "2.0.0"]);
+  });
+
+  it("returns source order for non-semantic versions", () => {
+    const original = ["latest", "1.0.0", "beta"];
+    expect(sortImageVersionsIfSemantic(original)).toEqual(original);
+  });
+});

app-new/backend/tsconfig.json

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+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "Node16",
+    "moduleResolution": "Node16",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "resolveJsonModule": true,
+    "rootDir": "src",
+    "outDir": "../../dist/backend",
+    "types": ["node", "vitest/globals"]
+  },
+  "include": ["src"]
+}