78 lines
3.1 KiB
TypeScript
78 lines
3.1 KiB
TypeScript
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import QRCode from "qrcode";
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/**
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* QR matrix builder for documents printed by `@react-pdf/renderer`.
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*
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* ## Why the matrix, and not a PNG
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*
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* A QR could be embedded as an image, but a matrix renders as pure
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* VECTOR — one `<Rect>` per dark module — which is strictly better
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* here:
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*
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* - it stays crisp at any print size or DPI, with no resampling
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* - it adds ~30 shapes rather than a compressed image blob, so the
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* PDF stays small
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* - it does not depend on react-pdf's raster image path at all.
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* That path was exactly what the old `pdf().toString()` pipeline
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* silently corrupted (see the note at the top of `render.tsx`),
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* and vector content is immune to it.
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*
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* ## What the QR carries
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*
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* Currently just the delivery note number, e.g. `DN26100401`.
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*
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* SECURITY NOTE — this is a deliberate product decision, not an
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* oversight. The number is a daily sequential counter (`DN{YY}{MM}{DD}{NN}`
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* starting at 01), so it is fully enumerable: anyone can guess every
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* delivery note that will ever exist. A QR carrying the bare number,
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* pointed at an upload endpoint, is therefore a signature-forgery
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* vector.
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*
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* That is acceptable *today* because the intended consumer is a
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* closed, logged-in internal app on the office network, not the public
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* internet. If this QR is ever exposed to customers, or the scan
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* target is ever made reachable without a login, the fix is to encode
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* an unguessable per-note token instead — e.g.
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* `DN26100401.<base64url(HMAC-SHA256(noteId, SIGNING_SECRET))[0..22]>`,
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* which needs no new column because it is recomputed rather than
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* stored. Raise it before the surface changes, not after.
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*/
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export type QrMatrix = {
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/** Modules per side, excluding the quiet zone. A version-1 code is 21. */
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size: number;
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/** Row-major, length `size * size`. `true` = dark module. */
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modules: boolean[];
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/**
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* QR spec requires 4 modules of light margin on every side, and
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* scanners rely on it. Without it a code sitting against other ink
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* on the page fails to decode, so the padding is part of the
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* contract, not decoration.
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*/
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quietZone: number;
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};
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/**
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* Encode `text` as a QR matrix.
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*
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* Error correction `M` (~15%) is the deliberate middle: enough to keep
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* the code readable through a thermal-grade print, a fingerprint smear
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* and a bent-in-a-pocket scan, without inflating the module count (and
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* so the physical size) the way `H` would for a payload this short.
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*/
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export function buildQrMatrix(text: string): QrMatrix {
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const trimmed = text.trim();
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if (!trimmed) {
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throw new Error("buildQrMatrix: refusing to encode an empty string");
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}
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const qr = QRCode.create(trimmed, { errorCorrectionLevel: "M" });
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const size = qr.modules.size;
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// `qr.modules.data` is a FLAT row-major Uint8Array of size*size.
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// (It is not an array of rows — `data[r]` is a single module, which
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// is a trap worth naming.)
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const modules: boolean[] = new Array(size * size);
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for (let i = 0; i < modules.length; i++) {
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modules[i] = qr.modules.data[i] === 1;
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}
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return { size, modules, quietZone: 4 };
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}
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