Loading indicator service indicating mempool sync status.

backend/src/api/loading-indicators.ts

@@ -0,0 +1,32 @@
+import { ILoadingIndicators } from '../mempool.interfaces';
+
+class LoadingIndicators {
+  private loadingIndicators: ILoadingIndicators = {
+    'mempool': 0,
+  };
+  private progressChangedCallback: ((loadingIndicators: ILoadingIndicators) => void) | undefined;
+
+  constructor() { }
+
+  public setProgressChangedCallback(fn: (loadingIndicators: ILoadingIndicators) => void) {
+    this.progressChangedCallback = fn;
+  }
+
+  public setProgress(name: string, progressPercent: number) {
+    const newProgress = Math.round(progressPercent);
+    if (newProgress >= 100) {
+      delete this.loadingIndicators[name];
+    } else {
+      this.loadingIndicators[name] = newProgress;
+    }
+    if (this.progressChangedCallback) {
+      this.progressChangedCallback(this.loadingIndicators);
+    }
+  }
+
+  public getLoadingIndicators() {
+    return this.loadingIndicators;
+  }
+}
+
+export default new LoadingIndicators();