Added some update APIs to check for updates and download and extract the update package.

Todo: apply updated, UI.

NzbDrone.Core/Providers/UpdateProvider.cs

@@ -0,0 +1,87 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Text.RegularExpressions;
+using NLog;
+using Ninject;
+using NzbDrone.Core.Model;
+using NzbDrone.Core.Providers.Core;
+
+namespace NzbDrone.Core.Providers
+{
+    class UpdateProvider
+    {
+        private readonly HttpProvider _httpProvider;
+        private readonly ConfigProvider _configProvider;
+        private readonly EnviromentProvider _enviromentProvider;
+        private readonly DiskProvider _diskProvider;
+        private static readonly Logger Logger = LogManager.GetCurrentClassLogger();
+
+        private static readonly Regex ParseRegex = new Regex(@"(?:\>)(?<filename>NzbDrone.+?(?<version>\d+\.\d+\.\d+\.\d+).+?)(?:\<\/A\>)", RegexOptions.IgnoreCase);
+
+        public const string SandboxFolderName = "nzbdrone_update";
+
+        [Inject]
+        public UpdateProvider(HttpProvider httpProvider, ConfigProvider configProvider, EnviromentProvider enviromentProvider, DiskProvider diskProvider)
+        {
+            _httpProvider = httpProvider;
+            _configProvider = configProvider;
+            _enviromentProvider = enviromentProvider;
+            _diskProvider = diskProvider;
+        }
+
+        public UpdateProvider()
+        {
+
+        }
+
+        private List<UpdatePackage> GetAvailablePackages()
+        {
+            var updateList = new List<UpdatePackage>();
+            var rawUpdateList = _httpProvider.DownloadString(_configProvider.UpdateUrl);
+            var matches = ParseRegex.Matches(rawUpdateList);
+
+            foreach (Match match in matches)
+            {
+                var updatePackage = new UpdatePackage();
+                updatePackage.FileName = match.Groups["filename"].Value;
+                updatePackage.Url = _configProvider.UpdateUrl + updatePackage.FileName;
+                updatePackage.Version = new Version(match.Groups["version"].Value);
+                updateList.Add(updatePackage);
+            }
+
+            return updateList;
+        }
+
+        public virtual UpdatePackage GetAvilableUpdate()
+        {
+            var latestAvailable = GetAvailablePackages().OrderByDescending(c => c.Version).FirstOrDefault();
+
+            if (latestAvailable != null && latestAvailable.Version > _enviromentProvider.Version)
+            {
+                Logger.Debug("An update is available ({0}) => ({1})", _enviromentProvider.Version, latestAvailable.Version);
+                return latestAvailable;
+            }
+
+            Logger.Trace("No updates available");
+            return null;
+        }
+
+        public virtual void PreformUpdate(UpdatePackage updatePackage)
+        {
+            var tempSubFolder = Path.Combine(_enviromentProvider.TempPath, SandboxFolderName);
+            var packageDestination = Path.Combine(tempSubFolder, updatePackage.FileName);
+
+            Logger.Info("Downloading update package from [{0}] to [{1}]", updatePackage.Url, packageDestination);
+            _httpProvider.DownloadFile(updatePackage.Url, packageDestination);
+            Logger.Info("Download completed for update package from [{0}]", updatePackage.FileName);
+
+            Logger.Info("Extracting Update package");
+            _diskProvider.ExtractArchive(packageDestination, tempSubFolder);
+            Logger.Info("Update package extracted successfully");
+        }
+
+    }
+}