# @einfach-produktiv/invoicing

Shared invoice / correction-invoice (Stornorechnung, Gutschrift) PDF generation and VAT-breakdown math, used by both:

- `einfach-produktiv` (the Next.js storefront — generates the original invoice at checkout, plus on-demand re-downloads of both document types)
- `payload` (the Payload CMS backend — generates the authoritative Stornorechnung/Gutschrift the moment an order's status changes)

## Why this exists

Before this package, `taxBreakdown.ts` and `correctionInvoicePdf.tsx` were hand-duplicated between both repos ("kept in sync by eye"). That drifted in three concrete, customer-visible ways before this package fixed it:

1. The backend's emailed correction invoice silently dropped each line item's `variantName` (the frontend's re-download copy showed it).
2. The backend's correction-invoice footer wasn't `position: fixed`, unlike the original invoice and the frontend's copy.
3. The backend's correction invoice used a numeric date format (`03.07.2025`); the original invoice and the frontend's re-download copy both used a spelled-out month (`03. Juli 2025`) — so a re-downloaded document didn't match what was originally emailed.

One canonical implementation, consumed by both repos, makes this class of drift structurally impossible instead of relying on manual vigilance.

## How this is consumed

Not published to npm — installed as a git dependency:

```json
"@einfach-produktiv/invoicing": "git+https://git.mk360.de/Marco/einfach-produktiv-invoicing.git"
```

Ships raw TypeScript/TSX source (no build step) via `main`/`types` pointing straight at `src/index.ts`. Each consuming Next.js app must add this package to its own `next.config.ts`'s `transpilePackages` array so its own bundler compiles the source — the same pattern a monorepo tool like Turborepo uses for internal packages, just without the monorepo.

`react` and `@react-pdf/renderer` are peer dependencies — each consumer supplies its own copy rather than this package pinning a version that could conflict.

## Layout

- `taxBreakdown.ts` — `computeTaxBreakdown()`, the per-VAT-rate net/tax grouping math shared by every document type here.
- `formatters.ts` — `formatPrice()`/`formatDate()`, canonical formatting for every document.
- `invoicePdf.tsx` — the original invoice ("Rechnung"): `InvoiceDocument`, `renderInvoicePdf()`, plus `SAMPLE_INVOICE_ORDER` (used by the frontend's Payload Live Preview for company-settings).
- `correctionInvoicePdf.tsx` — Stornorechnung/Gutschrift: `renderCorrectionInvoicePdf()`.
- `seller.ts` — the shared `InvoiceSeller` type both document types render in their footer.