add custom providers that can run before refresh chain

MediaBrowser.Controller/Providers/ICustomMetadataProvider.cs

@@ -14,4 +14,9 @@ namespace MediaBrowser.Controller.Providers
     {
         Task<ItemUpdateType> FetchAsync(TItemType item, IDirectoryService directoryService, CancellationToken cancellationToken);
     }
+
+    public interface IPreRefreshProvider : ICustomMetadataProvider
+    {
+        
+    }
 }

MediaBrowser.Providers/Manager/MetadataService.cs

@@ -269,6 +269,13 @@ namespace MediaBrowser.Providers.Manager
                 Providers = providers.Select(i => i.GetType().FullName.GetMD5()).ToList()
             };
 
+            var customProviders = providers.OfType<ICustomMetadataProvider<TItemType>>().ToList();
+
+            foreach (var provider in customProviders.Where(i => i is IPreRefreshProvider))
+            {
+                await RunCustomProvider(provider, item, options.DirectoryService, refreshResult, cancellationToken).ConfigureAwait(false);
+            }
+
             var temp = CreateNew();
             temp.Path = item.Path;
 
@@ -342,7 +349,7 @@ namespace MediaBrowser.Providers.Manager
                 MergeData(temp, item, item.LockedFields, true, true);
             }
 
-            foreach (var provider in providers.OfType<ICustomMetadataProvider<TItemType>>())
+            foreach (var provider in customProviders.Where(i => !(i is IPreRefreshProvider)))
             {
                 await RunCustomProvider(provider, item, options.DirectoryService, refreshResult, cancellationToken).ConfigureAwait(false);
             }
@@ -379,6 +386,9 @@ namespace MediaBrowser.Providers.Manager
         {
             TIdType id = null;
 
+            var unidentifiedCount = 0;
+            var identifiedCount = 0;
+
             foreach (var provider in providers)
             {
                 var providerName = provider.GetType().Name;
@@ -402,9 +412,12 @@ namespace MediaBrowser.Providers.Manager
                         MergeData(result.Item, temp, new List<MetadataFields>(), false, false);
 
                         refreshResult.UpdateType = refreshResult.UpdateType | ItemUpdateType.MetadataDownload;
+
+                        identifiedCount++;
                     }
                     else
                     {
+                        unidentifiedCount++;
                         Logger.Debug("{0} returned no metadata for {1}", providerName, item.Path ?? item.Name);
                     }
                 }
@@ -414,11 +427,20 @@ namespace MediaBrowser.Providers.Manager
                 }
                 catch (Exception ex)
                 {
+                    unidentifiedCount++;
                     refreshResult.Status = ProviderRefreshStatus.CompletedWithErrors;
                     refreshResult.ErrorMessage = ex.Message;
                     Logger.ErrorException("Error in {0}", ex, provider.Name);
                 }
             }
+
+            var isUnidentified = unidentifiedCount > 0 && identifiedCount == 0;
+
+            if (item.IsUnidentified != isUnidentified)
+            {
+                item.IsUnidentified = isUnidentified;
+                refreshResult.UpdateType = refreshResult.UpdateType | ItemUpdateType.MetadataImport;
+            }
         }
 
         private void MergeNewData(TItemType source, TIdType lookupInfo)