add missing billing check

Author: abraham

packages/cli/src/utils/billing.ts

@@ -0,0 +1,41 @@
+import { isBillingEnabled } from '../lib/billing.js';
+import type { DoctorCheckResult } from './node-version.js';
+
+const name = 'Blaze plan';
+
+/**
+ * Warns when the selected Firebase project isn't on the Blaze plan, which
+ * deploying Cloud Functions requires. Local development with the emulators
+ * works without it, so this never fails `doctor`.
+ */
+export const checkBilling = async (
+  repoRoot: string | undefined,
+  projectId: string | undefined,
+): Promise<DoctorCheckResult> => {
+  if (!repoRoot || !projectId) {
+    return { name, ok: true, warning: true, message: 'Skipped, no Firebase project selected.' };
+  }
+
+  try {
+    if (await isBillingEnabled(repoRoot, projectId)) {
+      return { name, ok: true, message: `Billing is enabled for ${projectId}.` };
+    }
+    return {
+      name,
+      ok: true,
+      warning: true,
+      message:
+        `${projectId} is not on the Blaze plan, which deploying Cloud Functions requires. ` +
+        `Upgrade at https://console.firebase.google.com/project/${projectId}/usage/details ` +
+        'and set a spend cap (see docs/tutorials/02-firebase.md#billing).',
+    };
+  } catch (error) {
+    const reason = error instanceof Error ? error.message : String(error);
+    return {
+      name,
+      ok: true,
+      warning: true,
+      message: `Could not check billing for ${projectId}: ${reason}`,
+    };
+  }
+};