Added a basic cache service to handle interations with the underlying cache implementation. Refactored some code to be more robust.

API/Extensions/ApplicationServiceExtensions.cs

@@ -19,6 +19,7 @@ namespace API.Extensions
             services.AddScoped<ITaskScheduler, TaskScheduler>();
             services.AddScoped<IUserRepository, UserRepository>();
             services.AddScoped<ITokenService, TokenService>();
+            services.AddScoped<ICacheService, CacheService>();
             services.AddScoped<ISeriesRepository, SeriesRepository>();
             services.AddScoped<IDirectoryService, DirectoryService>();
             services.AddScoped<ILibraryRepository, LibraryRepository>();

API/Extensions/ZipArchiveExtensions.cs

@@ -0,0 +1,19 @@
+using System.IO;
+using System.IO.Compression;
+using System.Linq;
+
+namespace API.Extensions
+{
+    public static class ZipArchiveExtensions
+    {
+        /// <summary>
+        /// Checks if archive has one or more files. Excludes directory entries. 
+        /// </summary>
+        /// <param name="archive"></param>
+        /// <returns></returns>
+        public static bool HasFiles(this ZipArchive archive)
+        {
+            return archive.Entries.Any(x => Path.HasExtension(x.FullName));
+        }
+    }
+}