1 files changed, 73 insertions, 0 deletions
diff --git a/MediaBrowser.Controller/Providers/ItemIdentifier.cs b/MediaBrowser.Controller/Providers/ItemIdentifier.cs
new file mode 100644
index 000000000..13e4f137f
--- /dev/null
+++ b/MediaBrowser.Controller/Providers/ItemIdentifier.cs
@@ -0,0 +1,73 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MediaBrowser.Controller.Providers
+{
+    public class ItemIdentifier<TLookupInfo, TIdentity>
+        where TLookupInfo : ItemLookupInfo
+        where TIdentity : IItemIdentity
+    {
+        public async Task<IEnumerable<TIdentity>> FindIdentities(TLookupInfo item, IProviderManager providerManager, CancellationToken cancellationToken)
+        {
+            var providers = providerManager.GetItemIdentityProviders<TLookupInfo, TIdentity>();
+            var converters = providerManager.GetItemIdentityConverters<TIdentity>();
+
+            var identities = new List<IdentityPair>();
+
+            foreach (var provider in providers)
+            {
+                var result = new IdentityPair
+                {
+                    Identity = await provider.FindIdentity(item),
+                    Order = provider.Order
+                };
+
+                if (!Equals(result.Identity, default(TIdentity)))
+                {
+                    identities.Add(result);
+                }
+            }
+
+            var convertersAvailable = new List<IItemIdentityConverter<TIdentity>>(converters);
+            bool changesMade;
+
+            do
+            {
+                changesMade = false;
+
+                for (int i = convertersAvailable.Count - 1; i >= 0; i--)
+                {
+                    var converter = convertersAvailable[i];
+                    var input = identities.FirstOrDefault(id => id.Identity.Type == converter.SourceType);
+                    var existing = identities.Where(id => id.Identity.Type == converter.ResultType);
+
+                    if (input != null && !existing.Any(id => id.Order <= converter.Order))
+                    {
+                        var result = new IdentityPair
+                        {
+                            Identity = await converter.Convert(input.Identity).ConfigureAwait(false),
+                            Order = converter.Order
+                        };
+
+                        if (!Equals(result.Identity, default(TIdentity)))
+                        {
+                            identities.Add(result);
+                            convertersAvailable.RemoveAt(i);
+                            changesMade = true;
+                        }
+                    }
+                }
+            } while (changesMade);
+
+            return identities.OrderBy(id => id.Order).Select(id => id.Identity);
+        }
+
+        private class IdentityPair
+        {
+            public TIdentity Identity;
+            public int Order;
+        }
+    }
+}
+\ No newline at end of file