octoturge
6b1c7c6db3
SnapshotView fetches one frame at a time through the backend, pauses while the tab is hidden and backs off after failures. PrinterCard picks it when /stream answers kind "snapshot".
79 lines
3.4 KiB
TypeScript
79 lines
3.4 KiB
TypeScript
/**
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* Where a printer's camera can be watched, from `GET /printers/:id/stream`.
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*/
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export type PrinterStream =
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| WebrtcStream
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// A P1/A1: no stream to negotiate, a picture to fetch again and again.
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| { kind: "snapshot"; snapshotPath: string; intervalMs: number };
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export interface WebrtcStream {
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kind?: "webrtc";
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/** The go2rtc stream name to negotiate for. */
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cameraId: string;
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/**
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* ICE servers for the player's `RTCPeerConnection`, minted per request and
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* short-lived. Empty when the backend has no TURN configured.
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*/
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iceServers: RTCIceServer[];
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/**
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* Whether TURN is configured at all, which is the difference between "no
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* relay is needed here" and "the relay is missing". Empty `iceServers`
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* with this true would mean minting silently failed.
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*/
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turnConfigured: boolean;
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}
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/**
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* Asks the backend where a printer's camera can be watched, or `null` if it
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* cannot.
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*
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* It returns no URL, and that is the point. A browser cannot reach a gateway
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* directly: go2rtc sends no CORS headers and checks its API password before
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* CORS, so an unauthenticated preflight gets a 401 - measured against
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* 1.9.14 - and a gateway sits behind a workshop NAT anyway. This used to
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* return the gateway's LAN address, which could only have worked for an
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* operator standing on that same network.
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*
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* So what comes back is a camera name and the ICE servers to negotiate with.
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* The offer goes to the backend, which relays it to the gateway over the
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* socket the gateway already holds open; the media then travels
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* browser-to-gateway through the TURN relay, DTLS-SRTP encrypted, so neither
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* the backend nor the relay can read it.
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*
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* A plain function and not a `useAsyncData` wrapper despite the file it lives
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* in: the caller needs one of these per printer, discovered from a list that
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* itself arrives asynchronously, and Nuxt's data composables may only be
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* called while a component is setting up. A loop over a resolved list is not
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* that. It takes the fetcher as an argument for the same reason - the caller
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* builds it in setup, where `useApiFetch` is valid.
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*
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* **Absence is the normal case, not an error.** Only Bambu's X1/H2 class
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* publishes a camera URL a gateway can restream; a P1 or A1 reports that it
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* has a camera and gives nothing to connect to. The backend answers 404 for
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* those, so this answers `null` and the caller shows no player at all -
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* rendering one that can never load would be worse than rendering nothing.
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*
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* The credentials are deliberately not cached: they are short-lived, so a
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* player that reconnects should ask again rather than retry a session with a
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* credential that has since expired.
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*/
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export async function fetchPrinterStream(
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apiFetch: ReturnType<typeof useApiFetch>,
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printerId: string,
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): Promise<PrinterStream | null> {
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try {
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return await apiFetch<PrinterStream>(`/printers/${printerId}/stream`);
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} catch (err: unknown) {
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// A 404 means "this printer has no watchable camera", which is expected
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// often enough that treating it as a failure would put an error state on
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// most cards in a mixed fleet. Anything else is a real problem: logged
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// and then treated as "no stream", because a broken camera lookup should
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// not take the fleet overview down with it.
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const status = (err as { statusCode?: number }).statusCode;
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if (status !== 404) {
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console.warn(`could not look up the camera stream for printer ${printerId}`, err);
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}
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return null;
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}
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}
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