app id service

src/Core/Abstractions/IAppIdService.cs

@@ -0,0 +1,10 @@
+using System.Threading.Tasks;
+
+namespace Bit.Core.Abstractions
+{
+    public interface IAppIdService
+    {
+        Task<string> GetAppIdAsync();
+        Task<string> GetAnonymousAppIdAsync();
+    }
+}

src/Core/Services/AppIdService.cs

@@ -0,0 +1,38 @@
+using Bit.Core.Abstractions;
+using System;
+using System.Threading.Tasks;
+
+namespace Bit.Core.Services
+{
+    public class AppIdService
+    {
+        private readonly IStorageService _storageService;
+
+        public AppIdService(IStorageService storageService)
+        {
+            _storageService = storageService;
+        }
+
+        public Task<string> GetAppIdAsync()
+        {
+            return MakeAndGetAppIdAsync("appId");
+        }
+
+        public Task<string> GetAnonymousAppIdAsync()
+        {
+            return MakeAndGetAppIdAsync("anonymousAppId");
+        }
+
+        private async Task<string> MakeAndGetAppIdAsync(string key)
+        {
+            var existingId = await _storageService.GetAsync<string>(key);
+            if(existingId != null)
+            {
+                return existingId;
+            }
+            var guid = Guid.NewGuid().ToString();
+            await _storageService.SaveAsync(key, guid);
+            return guid;
+        }
+    }
+}