moves NaiveSessionCache to web proj

src/Umbraco.Web/Security/Identity/NaiveSessionCache.cs

@@ -0,0 +1,84 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Web;
+using Microsoft.IdentityModel.Clients.ActiveDirectory;
+
+namespace Umbraco.Web.Security.Identity
+{
+    //NOTE: Not sure exactly what this is for but it is found in the AD source demo:
+    // https://github.com/AzureADSamples/WebApp-WebAPI-OpenIDConnect-DotNet/blob/master/TodoListWebApp/Utils/NaiveSessionCache.cs
+    // apparently it is needed for AD auth, so we'll put it here for people to use.
+    // It would appear that this is better for whatever reason: https://github.com/OfficeDev/O365-WebApp-SingleTenant/blob/master/O365-WebApp-SingleTenant/Models/ADALTokenCache.cs
+    // and please note that that link came from finding this thread: https://twitter.com/chakkaradeep/status/544962341528285184
+
+    /// <summary>
+    /// This is required to initialize the AD Identity provider on startup
+    /// </summary>
+    public class NaiveSessionCache : TokenCache
+    {
+        private static readonly object FileLock = new object();
+        readonly string _userObjectId = string.Empty;
+        readonly string _cacheId = string.Empty;
+        public NaiveSessionCache(string userId)
+        {
+            _userObjectId = userId;
+            _cacheId = _userObjectId + "_TokenCache";
+
+            this.AfterAccess = AfterAccessNotification;
+            this.BeforeAccess = BeforeAccessNotification;
+            Load();
+        }
+
+        public void Load()
+        {
+            lock (FileLock)
+            {
+                this.Deserialize((byte[])HttpContext.Current.Session[_cacheId]);
+            }
+        }
+
+        public void Persist()
+        {
+            lock (FileLock)
+            {
+                // reflect changes in the persistent store
+                HttpContext.Current.Session[_cacheId] = this.Serialize();
+                // once the write operation took place, restore the HasStateChanged bit to false
+                this.HasStateChanged = false;
+            }
+        }
+
+        // Empties the persistent store.
+        public override void Clear()
+        {
+            base.Clear();
+            System.Web.HttpContext.Current.Session.Remove(_cacheId);
+        }
+
+        public override void DeleteItem(TokenCacheItem item)
+        {
+            base.DeleteItem(item);
+            Persist();
+        }
+
+        // Triggered right before ADAL needs to access the cache.
+        // Reload the cache from the persistent store in case it changed since the last access.
+        void BeforeAccessNotification(TokenCacheNotificationArgs args)
+        {
+            Load();
+        }
+
+        // Triggered right after ADAL accessed the cache.
+        void AfterAccessNotification(TokenCacheNotificationArgs args)
+        {
+            // if the access operation resulted in a cache update
+            if (this.HasStateChanged)
+            {
+                Persist();
+            }
+        }
+    }
+}