implement cancelNotification

src/resolvers/MutationResolvers.ts

@@ -29,11 +29,19 @@ export const MutationResolvers: Resolvers<ServerContext> = {
       return response;
     },
     cancelNotification: async (_parent, args, context, _info) => {
-      const response: NotificationResponse = {
-        message: "Not implemented",
-        success: false
+      if (context.notificationService.isNotificationScheduled(args.input)) {
+        await context.notificationService.cancelNotificationIfExists(args.input);
+        return {
+          success: true,
+          message: "Notification cancelled",
+          data: args.input,
+        }
+      }
+
+      return {
+        success: false,
+        message: "Notification doesn't exist"
       }
-      return response;
     },
   },
 }