From 4a62b9e8cb734ca619d836a5948a373b87fea064 Mon Sep 17 00:00:00 2001
From: Kevin Hahn <kevin_hahn@sil.org>
Date: Wed, 10 Jul 2024 15:44:32 +0700
Subject: [PATCH] setup generic signalr error handling

---
 backend/FwLite/LocalWebApp/Program.cs         |  1 +
 frontend/viewer/src/FwDataProjectView.svelte  | 14 ++++++++++--
 .../lib/services/service-provider-signalr.ts  | 22 +++++++++++++++++--
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/backend/FwLite/LocalWebApp/Program.cs b/backend/FwLite/LocalWebApp/Program.cs
index 151beb5aa..753f32660 100644
--- a/backend/FwLite/LocalWebApp/Program.cs
+++ b/backend/FwLite/LocalWebApp/Program.cs
@@ -29,6 +29,7 @@
 builder.Services.AddSignalR(options =>
 {
     options.AddFilter(new LockedProjectFilter());
+    options.EnableDetailedErrors = true;
 }).AddJsonProtocol();
 
 var app = builder.Build();
diff --git a/frontend/viewer/src/FwDataProjectView.svelte b/frontend/viewer/src/FwDataProjectView.svelte
index 046bbf549..90519ec92 100644
--- a/frontend/viewer/src/FwDataProjectView.svelte
+++ b/frontend/viewer/src/FwDataProjectView.svelte
@@ -23,7 +23,6 @@
         console.error('Failed to start the connection:', err);
       });
   }
-
   connect();
   onDestroy(() => connection.stop());
   connection.onclose(error => {
@@ -54,7 +53,18 @@
             break;
         }
       }
-    });
+    },
+    (errorContext) => {
+
+      connected = false;
+      if (errorContext.error instanceof Error) {
+        let message = errorContext.error.message;
+        AppNotification.display('Connection error: ' + message, 'error', 'long');
+      } else {
+        AppNotification.display('Unknown Connection error', 'error', 'long');
+      }
+    }
+  );
   let connected = false;
 </script>
 <ProjectView {projectName} isConnected={connected}></ProjectView>
diff --git a/frontend/viewer/src/lib/services/service-provider-signalr.ts b/frontend/viewer/src/lib/services/service-provider-signalr.ts
index d7edb9560..996a2a842 100644
--- a/frontend/viewer/src/lib/services/service-provider-signalr.ts
+++ b/frontend/viewer/src/lib/services/service-provider-signalr.ts
@@ -5,9 +5,27 @@ import type { LexboxApiFeatures, LexboxApiMetadata } from './lexbox-api';
 import {LexboxService} from './service-provider';
 import type {ILexboxClient} from '../generated-signalr-client/TypedSignalR.Client/Lexbox.ClientServer.Hubs';
 
-
-export function SetupSignalR(connection: HubConnection, features: LexboxApiFeatures, client: ILexboxClient | null = null) {
+type ErrorContext = {error: Error|unknown, methodName: string};
+export function SetupSignalR(connection: HubConnection, features: LexboxApiFeatures, client: ILexboxClient | null = null, onError?: (context: ErrorContext) => void) {
   const hubFactory = getHubProxyFactory('ILexboxApiHub');
+  if (onError) {
+    connection = new Proxy(connection, {
+      get(target, prop: keyof HubConnection, receiver) {
+        if (prop === 'invoke') {
+          return async (methodName: string, ...args: any[]) => {
+            try {
+              return await target.invoke(methodName, ...args);
+            } catch (e) {
+              onError({error: e, methodName});
+              throw e;
+            }
+          }
+        } else {
+          return Reflect.get(target, prop, receiver);
+        }
+      }
+    }) as HubConnection;
+  }
   const hubProxy = hubFactory.createHubProxy(connection);
 
   const lexboxApiHubProxy = Object.assign(hubProxy, {