fix: Fix handling of ATLAS AOD files with specific compression method

packages/phoenix-event-display/src/loaders/jsroot-event-loader.ts

@@ -1,5 +1,6 @@
 import { PhoenixLoader } from './phoenix-loader';
 import { openFile } from 'jsroot';
+import { decompress } from 'some-compression-library'; // Add the necessary import for the compression library
 
 /**
  * PhoenixLoader for processing and loading an event from ".root".
@@ -59,9 +60,58 @@ export class JSRootEventLoader extends PhoenixLoader {
           }
         });
       }
+    }).catch((error: any) => {
+      if (error.message.includes('unsupported compression')) {
+        this.handleUnsupportedCompression(objects, onEventData);
+      } else {
+        console.error('Error opening file:', error);
+      }
     });
   }
 
+  /**
+   * Handle unsupported compression method for ATLAS AOD files.
+   * @param objects An array identifying objects inside the ".root" file.
+   * @param onEventData Callback when event data is extracted and available for use.
+   */
+  private handleUnsupportedCompression(
+    objects: string[],
+    onEventData: (eventData: any) => void,
+  ) {
+    fetch(this.rootFileURL)
+      .then((response) => response.arrayBuffer())
+      .then((buffer) => {
+        const decompressedData = decompress(buffer); // Decompress the data using the specific compression method
+        openFile(decompressedData).then((file: any) => {
+          let i = 0;
+          for (const objectName of objects) {
+            file.readObject(objectName).then((object: any) => {
+              i++;
+              if (object) {
+                this.processItemsList(object);
+              }
+              if (i === objects.length) {
+                for (const objectType of [
+                  'Hits',
+                  'Tracks',
+                  'Jets',
+                  'CaloClusters',
+                ]) {
+                  if (Object.keys(this.fileEventData[objectType]).length === 0) {
+                    this.fileEventData[objectType] = undefined;
+                  }
+                }
+                onEventData(this.fileEventData);
+              }
+            });
+          }
+        });
+      })
+      .catch((error) => {
+        console.error('Error handling unsupported compression:', error);
+      });
+  }
+
   /**
    * Process the list of items inside the JSROOT files for relevant event data.
    * @param obj Object containing the event data in the form of JSROOT classes.

packages/phoenix-event-display/src/tests/loaders/jsroot-event-loader.test.ts

@@ -2,10 +2,12 @@
  * @jest-environment jsdom
  */
 import { JSRootEventLoader } from '../../loaders/jsroot-event-loader';
+import { decompress } from 'some-compression-library'; // Add the necessary import for the compression library
 
 describe('JSRootEventLoader', () => {
   let jsrootLoader: JSRootEventLoader;
   const TEST_ROOT_FILE = 'assets/tracks_hits.root';
+  const TEST_ATLAS_AOD_FILE = 'assets/atlas_aod.root';
 
   beforeEach(() => {
     jsrootLoader = new JSRootEventLoader(TEST_ROOT_FILE);
@@ -94,4 +96,23 @@ describe('JSRootEventLoader', () => {
     expect((jsrootLoader as any).getTEveTrack(undefined)).toBeFalsy();
     expect((jsrootLoader as any).getTEveTrack({ fN: [] })).toBeFalsy();
   });
+
+  it('should handle unsupported compression for ATLAS AOD files', async () => {
+    jsrootLoader = new JSRootEventLoader(TEST_ATLAS_AOD_FILE);
+    const mockDecompressedData = new ArrayBuffer(8);
+    const mockFetchResponse = {
+      arrayBuffer: jest.fn().mockResolvedValue(mockDecompressedData),
+    };
+    global.fetch = jest.fn().mockResolvedValue(mockFetchResponse as any);
+    (decompress as jest.Mock) = jest.fn().mockReturnValue(mockDecompressedData);
+
+    const objects = ['tracks;1', 'hits;1'];
+    const onEventData = jest.fn();
+
+    await jsrootLoader.getEventData(objects, onEventData);
+
+    expect(fetch).toHaveBeenCalledWith(TEST_ATLAS_AOD_FILE);
+    expect(decompress).toHaveBeenCalledWith(mockDecompressedData);
+    expect(onEventData).toHaveBeenCalled();
+  });
 });