feat(street-level): provider exports and a Mapillary Graph endpoint for hosts (#1324)

* feat(street-level): export the KartaView and Panoramax providers

A host that composes Street Level with its own provider list can already
import the Mapillary and Google Street View providers; KartaView and Panoramax
were reachable only through the default list, which needs a Mapillary source.
Exporting them lets a host offer the keyless providers without Mapillary.

* chore: changelog entry for the Street Level provider exports

* feat(street-level): send Mapillary Graph lookups to a source endpoint

A Mapillary source can take a graphEndpoint, a Graph API base that adds
the token itself. Its sequence lookups go there through the source's
transport, and the photo viewer uses MapillaryJS's stock GraphDataProvider
at that endpoint, so a host that proxies Mapillary needs no client token in
the page. Without it, behaviour is unchanged: direct Graph API calls with
the client token.

src/app/layers/streetLevel.test.mjs

@@ -72,3 +72,17 @@ test('the defaults are Mapillary (given its source), Street View, KartaView and
   // Without the application's Street Level source there are none.
   assert.deepEqual(createApplicationStreetLevel({}).providerIds, []);
 });
+
+test('every built-in provider is exported, so hosts can choose their own list', async () => {
+  const google = await import('gods-eye-view/layers/street-level/google');
+  const kartaview = await import('gods-eye-view/layers/street-level/kartaview');
+  const panoramax = await import('gods-eye-view/layers/street-level/panoramax');
+  const layer = createApplicationStreetLevel({
+    providers: [
+      google.createGoogleProvider({ getApiKey: () => null }),
+      kartaview.createKartaViewProvider(),
+      panoramax.createPanoramaxProvider(),
+    ],
+  });
+  assert.deepEqual(layer.providerIds, ['google', 'kartaview', 'panoramax']);
+});

src/layers/streetLevel/providers/mapillary/source.js

@@ -36,16 +36,29 @@ async function readJsonOrThrow(response, label) {
   return payload;
 }
 
+/** `endpoint` with exactly one trailing slash, or '' when unset. */
+function endpointBase(endpoint) {
+  const text = String(endpoint || '').trim();
+  return text ? text.replace(/\/*$/, '/') : '';
+}
+
 /**
  * Mapillary network access: tiles via the local proxy, which adds the token
  * and caches; Graph API lookups direct with the client token, as MapillaryJS.
- * @param {{token?: string, fetchImpl?: Function, endpoints?: object}} options
+ * With `graphEndpoint` (a Graph API base that adds the token itself, such as
+ * a same-origin proxy), the source's Graph lookups go there through
+ * `fetchImpl` instead, and the photo viewer sends its own lookups there too;
+ * no token is sent or needed.
+ * @param {{token?: string, fetchImpl?: Function, endpoints?: object,
+ *   graphEndpoint?: string}} options
  */
 export function createMapillarySource({
   token = '',
   fetchImpl = (...args) => globalThis.fetch(...args),
   endpoints = {},
+  graphEndpoint = '',
 } = {}) {
+  const graphBase = endpointBase(graphEndpoint);
   const urls = {
     status: '/api/mapillary/status',
     tiles: '/api/mapillary/tiles',
@@ -54,6 +67,13 @@ export function createMapillarySource({
   };
 
   async function graph(path, params = {}, { signal } = {}) {
+    if (graphBase) {
+      const search = new URLSearchParams(params);
+      const response = await fetchImpl(`${graphBase}${path}?${search}`, {
+        signal,
+      });
+      return readJsonOrThrow(response, 'Mapillary graph');
+    }
     if (!token)
       throw new MapillarySourceError('Mapillary token not configured', {
         status: 503,
@@ -70,6 +90,10 @@ export function createMapillarySource({
     get token() {
       return token;
     },
+    /** The Graph API base that adds the token itself, or '' (direct). */
+    get graphEndpoint() {
+      return graphBase;
+    },
     hasToken: () => Boolean(token),
 
     async getStatus({ signal } = {}) {

src/layers/streetLevel/providers/mapillary/source.test.mjs

@@ -125,3 +125,35 @@ test('a rejected key and a rate limit are told apart from other tile errors', as
     'the Retry-After header wins over the body',
   );
 });
+
+test('with a Graph endpoint, sequence lookups go there without a token', async () => {
+  const { calls, fetchImpl } = fakeFetch(() =>
+    jsonResponse({ data: [{ id: '1', geometry: { coordinates: [1, 2] } }] }),
+  );
+  const source = createMapillarySource({
+    graphEndpoint: '/api/mapillary/graph',
+    fetchImpl,
+  });
+  assert.equal(source.graphEndpoint, '/api/mapillary/graph/');
+  assert.equal(source.hasToken(), false);
+  const images = await source.getSequenceImages('seq-1');
+  assert.equal(images.length, 1);
+  const url = new URL(calls[0].url, 'http://localhost');
+  assert.equal(url.pathname, '/api/mapillary/graph/images');
+  assert.equal(url.searchParams.get('sequence_ids'), 'seq-1');
+  assert.equal(url.searchParams.has('access_token'), false);
+});
+
+test('Graph endpoint errors keep their status', async () => {
+  const { fetchImpl } = fakeFetch(() =>
+    jsonResponse({ error: 'no_key', keyRequired: true }, 503),
+  );
+  const source = createMapillarySource({
+    graphEndpoint: '/api/mapillary/graph/',
+    fetchImpl,
+  });
+  await assert.rejects(
+    () => source.getSequenceImages('1'),
+    (error) => error.status === 503 && error.keyRequired === true,
+  );
+});

src/layers/streetLevel/providers/mapillary/viewer.js

@@ -13,6 +13,20 @@ import { mapillaryImageUrl } from './policy.js';
  * @property {string} externalUrl      Deep link to the image on mapillary.com.
  */
 
+/**
+ * The source's Graph endpoint as an absolute URL ending in `/`, as MapillaryJS
+ * resolves its lookup paths against it; '' when the source has none.
+ */
+export function graphEndpointUrl(source) {
+  if (!source?.graphEndpoint) return '';
+  const url = new URL(
+    source.graphEndpoint,
+    globalThis.location?.href || 'http://localhost/',
+  );
+  url.pathname = url.pathname.replace(/\/*$/, '/');
+  return url.href;
+}
+
 /**
  * The panel's photo viewer: loads MapillaryJS on the first `mount` and emits
  * a pose on every image, view or position change.
@@ -115,12 +129,18 @@ export function createMapillaryViewer({ source, render } = {}) {
   async function buildViewer(host) {
     const built = generation;
     destroyViewer();
-    const { Viewer } = await ensureLibrary();
+    const { Viewer, GraphDataProvider } = await ensureLibrary();
     // Unmounted (layer off) while the library loaded: a viewer built now
     // would hold a WebGL context nobody releases.
     if (built !== generation) throw new Error('Mapillary viewer was unmounted');
+    const endpoint = graphEndpointUrl(source);
     viewer = new Viewer({
-      accessToken: source.token,
+      // A source with its own Graph endpoint (which adds the token itself)
+      // answers the viewer's lookups, sent without a token; otherwise
+      // MapillaryJS calls the Graph API with the client token.
+      ...(endpoint
+        ? { dataProvider: new GraphDataProvider({ endpoint }) }
+        : { accessToken: source.token }),
       container: host,
       component: {
         cover: false,

src/layers/streetLevel/viewerHost.test.mjs

@@ -22,13 +22,16 @@ registerHooks({
     const source = url.includes('/library?')
       ? 'const lib = await globalThis.__gevMapillaryLibrary();\n' +
         'export const Viewer = lib.Viewer;\n' +
-        'export const RenderMode = lib.RenderMode;\n'
+        'export const RenderMode = lib.RenderMode;\n' +
+        'export const GraphDataProvider = lib.GraphDataProvider;\n'
       : 'export default {};\n';
     return { format: 'module', shortCircuit: true, source };
   },
 });
-const { createMapillaryViewer } =
+const { createMapillaryViewer, graphEndpointUrl } =
   await import('./providers/mapillary/viewer.js');
+const { createMapillarySource } =
+  await import('./providers/mapillary/source.js');
 
 /**
  * A viewer host over `adapter`. `marker` records where the position marker
@@ -345,7 +348,7 @@ function fakeLibrary() {
   }
   globalThis.__gevMapillaryLibrary = async () => {
     await gate.promise;
-    return { Viewer, RenderMode: {} };
+    return { Viewer, RenderMode: {}, GraphDataProvider: FakeGraphDataProvider };
   };
   return { gate, viewers };
 }
@@ -565,3 +568,52 @@ test('a pose’s licence reaches the caption state, and a closed viewer forgets
   host.close();
   assert.equal(state.street.license, null);
 });
+
+/** MapillaryJS 4's Graph provider, recording what it was built with. */
+class FakeGraphDataProvider {
+  constructor(options = {}) {
+    this.options = options;
+  }
+}
+
+test('without a Graph endpoint the viewer gets the client token, as before', async () => {
+  const library = fakeLibrary();
+  library.gate.resolve();
+  const adapter = createMapillaryViewer({ source: { token: 't' } });
+  await adapter.mount({});
+  const [viewer] = library.viewers.instances;
+  assert.equal(viewer.options.accessToken, 't');
+  assert.equal(viewer.options.dataProvider, undefined);
+});
+
+test("with a Graph endpoint the viewer uses MapillaryJS's Graph provider there, without a token", async () => {
+  const library = fakeLibrary();
+  library.gate.resolve();
+  const source = createMapillarySource({
+    graphEndpoint: 'https://app.example/api/mapillary/graph',
+    fetchImpl: async () => {
+      throw new Error('the viewer does not use the source transport');
+    },
+  });
+  const adapter = createMapillaryViewer({ source });
+  await adapter.mount({});
+  const [viewer] = library.viewers.instances;
+  assert.equal(viewer.options.accessToken, undefined);
+  const provider = viewer.options.dataProvider;
+  assert.ok(provider instanceof FakeGraphDataProvider);
+  assert.deepEqual(provider.options, {
+    endpoint: 'https://app.example/api/mapillary/graph/',
+  });
+});
+
+test('a relative Graph endpoint resolves against the page, with one trailing slash', () => {
+  assert.equal(
+    graphEndpointUrl({ graphEndpoint: '/api/mapillary/graph' }),
+    'http://localhost/api/mapillary/graph/',
+  );
+  assert.equal(
+    graphEndpointUrl({ graphEndpoint: '/api/mapillary/graph//' }),
+    'http://localhost/api/mapillary/graph/',
+  );
+  assert.equal(graphEndpointUrl({ token: 't' }), '');
+});