1 files changed, 104 insertions, 0 deletions
diff --git a/MediaBrowser.Controller/Providers/BaseMetadataProvider.cs b/MediaBrowser.Controller/Providers/BaseMetadataProvider.cs
new file mode 100644
index 000000000..50004be44
--- /dev/null
+++ b/MediaBrowser.Controller/Providers/BaseMetadataProvider.cs
@@ -0,0 +1,104 @@
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Common.Extensions;
+using System.Threading.Tasks;
+using System;
+
+namespace MediaBrowser.Controller.Providers
+{
+    public abstract class BaseMetadataProvider
+    {
+        protected Guid _id;
+        public virtual Guid Id
+        {
+            get
+            {
+                if (_id == null) _id = this.GetType().FullName.GetMD5();
+                return _id;
+            }
+        }
+
+        public abstract bool Supports(BaseEntity item);
+
+        public virtual bool RequiresInternet
+        {
+            get
+            {
+                return false;
+            }
+        }
+
+        /// <summary>
+        /// Returns the last refresh time of this provider for this item. Providers that care should
+        /// call SetLastRefreshed to update this value.
+        /// </summary>
+        /// <param name="item"></param>
+        /// <returns></returns>
+        protected virtual DateTime LastRefreshed(BaseEntity item)
+        {
+            return (item.ProviderData.GetValueOrDefault(this.Id, new BaseProviderInfo())).LastRefreshed;
+        }
+
+        /// <summary>
+        /// Sets the persisted last refresh date on the item for this provider.
+        /// </summary>
+        /// <param name="item"></param>
+        /// <param name="value"></param>
+        protected virtual void SetLastRefreshed(BaseEntity item, DateTime value)
+        {
+            var data = item.ProviderData.GetValueOrDefault(this.Id, new BaseProviderInfo());
+            data.LastRefreshed = value;
+            item.ProviderData[this.Id] = data;
+        }
+
+        /// <summary>
+        /// Returns whether or not this provider should be re-fetched.  Default functionality can
+        /// compare a provided date with a last refresh time.  This can be overridden for more complex
+        /// determinations.
+        /// </summary>
+        /// <returns></returns>
+        public virtual bool NeedsRefresh(BaseEntity item)
+        {
+            return CompareDate(item) > LastRefreshed(item);
+        }
+
+        /// <summary>
+        /// Override this to return the date that should be compared to the last refresh date
+        /// to determine if this provider should be re-fetched.
+        /// </summary>
+        protected virtual DateTime CompareDate(BaseEntity item)
+        {
+            return DateTime.MinValue.AddMinutes(1); // want this to be greater than mindate so new items will refresh
+        }
+
+        public virtual Task FetchIfNeededAsync(BaseEntity item)
+        {
+            if (this.NeedsRefresh(item))
+                return FetchAsync(item, item.ResolveArgs);
+            else
+                return new Task(() => { });
+        }
+            
+        public abstract Task FetchAsync(BaseEntity item, ItemResolveEventArgs args);
+
+        public abstract MetadataProviderPriority Priority { get; }
+    }
+
+    /// <summary>
+    /// Determines when a provider should execute, relative to others
+    /// </summary>
+    public enum MetadataProviderPriority
+    {
+        // Run this provider at the beginning
+        First = 1,
+
+        // Run this provider after all first priority providers
+        Second = 2,
+
+        // Run this provider after all second priority providers
+        Third = 3,
+
+        // Run this provider last
+        Last = 4
+    }
+}