Provides reusable utility functions for currency formatting, date formatting, Y-axis label generation for charts, and pagination logic. The `generatePagination` function handles ellipsis logic for page numbers, and `generateYAxis` computes chart axis labels. These are self-contained and can be extracted into any project needing similar formatting or pagination.

A client-side pagination component that uses URL search params to manage page state. It renders numbered page links with ellipsis, handles active state styling, and provides arrow buttons. The component is self-contained, uses `usePathname` and `useSearchParams` from Next.js, and can be reused in any list view with pagination.

Implements server actions for creating, updating, and deleting invoices, as well as authentication. Uses Zod for form validation with detailed error messages, and handles database errors gracefully. The pattern of using `useActionState` with typed state is a clean example of form handling in Next.js App Router. The `authenticate` action demonstrates credential-based login with NextAuth.

Demonstrates dynamic imports for code splitting: the `CodeSampleModal` component is loaded lazily with `next/dynamic`, and Fuse.js and lodash are imported dynamically inside an event handler. This pattern improves initial load performance by deferring non-critical code. The component is a self-contained modal using `react-modal` and `react-syntax-highlighter`, and the dynamic import pattern is reusable for any heavy component.