fix(synology): journey photos keep their own capture date and place, not the next photo's

getSynologyAssetInfo asked Browse.Item for the unit id plus one, a fixed
offset that holds on some libraries and on others names the next photo, whose
date and GPS were then stored for the attached one. It now asks for the unit
id, then for the one after, and takes only an item whose own thumbnail belongs
to the requested unit; when neither does, it answers not found instead of a
neighbour's metadata.

Closes #3019

server/src/nest/memories/synology.service.ts

@@ -732,24 +732,47 @@ export class SynologyService {
   ): Promise<ServiceResult<AssetInfo>> {
     const parsedId = this._splitPackedSynologyId(photoId);
     if (!parsedId) return fail('Invalid photo ID format', 400);
-    const infoParams: ApiCallParams = {
-      api: 'SYNO.Foto.Browse.Item',
-      method: 'get',
-      version: 5,
-      id: `[${Number(parsedId.id) + 1}]`, //for some reason synology wants id moved by one to get image info
-      additional: ['resolution', 'exif', 'gps', 'address', 'orientation', 'description'],
-    };
-    if (passphrase) infoParams.passphrase = passphrase;
-    const result = await this._requestSynologyApi<{ list: SynologyPhotoItem[] }>(targetUserId, infoParams);
 
-    if (!result.success) return result as ServiceResult<AssetInfo>;
+    // The packed id carries the thumbnail's unit id, while Browse.Item `get`
+    // wants the item's own id. On most libraries the two are equal; on some the
+    // item is one further on, which is why this once always asked for unit + 1
+    // and, on the others, stored the next photo's date and place (#3019). So
+    // both are asked in turn, and only an item whose own thumbnail is this unit
+    // counts: never a neighbour's capture time or GPS.
+    const unit = Number(parsedId.id);
+    let lastFailure: ServiceResult<AssetInfo> = fail('Photo not found', 404);
+    for (const itemId of [unit, unit + 1]) {
+      const infoParams: ApiCallParams = {
+        api: 'SYNO.Foto.Browse.Item',
+        method: 'get',
+        version: 5,
+        id: `[${itemId}]`,
+        additional: ['thumbnail', 'resolution', 'exif', 'gps', 'address', 'orientation', 'description'],
+      };
+      if (passphrase) infoParams.passphrase = passphrase;
+      const result = await this._requestSynologyApi<{ list: SynologyPhotoItem[] }>(targetUserId, infoParams);
+      if (!result.success) {
+        lastFailure = result as ServiceResult<AssetInfo>;
+        continue;
+      }
+      const metadata = result.data.list?.find((item) => this._isItemOfUnit(item, parsedId.id));
+      if (!metadata) continue;
 
-    const metadata = result.data.list?.[0];
-    if (!metadata) return fail('Photo not found', 404);
+      const normalized = this._normalizeSynologyPhotoInfo(metadata);
+      normalized.id = photoId;
+      return success(normalized);
+    }
+    return lastFailure;
+  }
 
-    const normalized = this._normalizeSynologyPhotoInfo(metadata);
-    normalized.id = photoId;
-    return success(normalized);
+  /**
+   * Whether an item from Browse.Item is the one behind a unit id: its thumbnail's
+   * cache key starts with that unit. The key's second half is a timestamp that
+   * moves when the photo is edited, so the unit alone decides.
+   */
+  private _isItemOfUnit(item: SynologyPhotoItem, unitId: string): boolean {
+    const key = String(item.additional?.thumbnail?.cache_key ?? '');
+    return key.split('_')[0] === unitId;
   }
 
   async fetchSynologyThumbnailBytes(

server/tests/unit/nest/synology.service.test.ts

@@ -531,6 +531,66 @@ describe('the search window', () => {
   });
 });
 
+describe('getSynologyAssetInfo', () => {
+  /** A Browse.Item `get` answer holding one item, its thumbnail keyed to a unit. */
+  const item = (cacheKey: string, time: number) =>
+    api({
+      list: [{ id: 1, time, additional: { thumbnail: { cache_key: cacheKey }, gps: { latitude: 1, longitude: 2 } } }],
+    });
+  const requestedIds = () =>
+    safeFetch.mock.calls.map((c) => new URLSearchParams(String((c[1] as { body: URLSearchParams }).body)).get('id'));
+  const takenAt = (r: unknown) => (r as { data: { takenAt: string } }).data.takenAt;
+
+  it('SYNO-U090: reads the asset itself where the item id is its unit id, not the next photo (#3019)', async () => {
+    safeFetch.mockResolvedValueOnce(item('10314_1793757217', 1718236800));
+
+    const result = await svc.getSynologyAssetInfo(USER, '10314_1793757217', USER);
+
+    expect(requestedIds()).toEqual(['[10314]']);
+    expect(takenAt(result)).toBe(new Date(1718236800 * 1000).toISOString());
+    expect((result as { data: { id: string } }).data.id).toBe('10314_1793757217');
+  });
+
+  it('SYNO-U091: where the item is one further on, takes that one and not the neighbour the unit id names', async () => {
+    safeFetch
+      .mockResolvedValueOnce(item('10313_1700000000', 1500000000))
+      .mockResolvedValueOnce(item('10314_1793757217', 1718236800));
+
+    const result = await svc.getSynologyAssetInfo(USER, '10314_1793757217', USER);
+
+    expect(requestedIds()).toEqual(['[10314]', '[10315]']);
+    expect(takenAt(result)).toBe(new Date(1718236800 * 1000).toISOString());
+  });
+
+  it("SYNO-U092: answers not found rather than another photo's date and place", async () => {
+    safeFetch
+      .mockResolvedValueOnce(item('10313_1700000000', 1500000000))
+      .mockResolvedValueOnce(item('10316_1700000000', 1500000000));
+
+    const result = await svc.getSynologyAssetInfo(USER, '10314_1793757217', USER);
+
+    expect(result).toEqual({ success: false, error: { message: 'Photo not found', status: 404 } });
+  });
+
+  it('SYNO-U093: matches an edited photo by its unit, whatever timestamp its key carries now', async () => {
+    safeFetch.mockResolvedValueOnce(item('10314_1800000000', 1718236800));
+
+    const result = await svc.getSynologyAssetInfo(USER, '10314_1793757217', USER);
+
+    expect(result.success).toBe(true);
+    expect(requestedIds()).toEqual(['[10314]']);
+  });
+
+  it('SYNO-U094: asks for the thumbnail with the metadata, the only way to tell which photo answered', async () => {
+    safeFetch.mockResolvedValueOnce(item('10314_1793757217', 1718236800));
+
+    await svc.getSynologyAssetInfo(USER, '10314_1793757217', USER);
+
+    const body = new URLSearchParams(String((safeFetch.mock.calls[0][1] as { body: URLSearchParams }).body));
+    expect(body.get('additional')).toContain('thumbnail');
+  });
+});
+
 describe('fetchSynologyThumbnailBytes', () => {
   it('SYNO-U080: fails without credentials rather than fetching', async () => {
     await seedUser(6, { synology_url: null });