Adding --latest-only option (#15)

* Adding --latest-only option

By default, any duplicate packages that are found will be processed, resulting in multiple versions of the same package in the feed. In case you have a build process that retains older versions of VSIX packages, this option can be used to ensure only the latest version of packages with the same ID end up in the feed.

* Refactoring latest version to be much simpler.

Removing private method and switching to use a one-line LINQ statement.
It's probably slightly less efficient, but I think the simpler code outweighs the minor performance hit.

README.md

@@ -78,12 +78,26 @@ PrivateGalleryCreator.exe --exclude=dontwantthis
 ```
 
 ## Source option
-Be default, the download source path used in the gallery will be the location where the .vsix files reside when running the PrivateGalleryCreator. If you intend to move the .vsix files after creating the feed, you can specify the intended download source path with the --source option:
+By default, the download source path used in the gallery will be the location where the .vsix files reside when running the PrivateGalleryCreator. If you intend to move the .vsix files after creating the feed, you can specify the intended download source path with the --source option:
 
 ```cmd
 PrivateGalleryCreator.exe --source=c:\your\vsix\repository\
 ```
 
+## Terminate option
+If you would like the application to exit immediately after processing VSIX files, use the --terminate option:
+
+```cmd
+PrivateGalleryCreator.exe --terminate
+```
+
+## Latest only option
+By default, any duplicate packages that are found will be processed, resulting in multiple versions of the same package in the feed. If you have a folder structure that retains previous versions of the packages, use the --latest-only option:
+
+```cmd
+PrivateGalleryCreator.exe --latest-only
+```
+
 ## Good to know
 
 * Run the *PrivateGalleryCreator.exe* every time you add or update a .vsix in the directory

src/Program.cs

@@ -13,6 +13,7 @@ internal class Program
     private static string _dir;
     private static string _galleryName;
     private static bool _recursive = false;
+    private static bool _latestOnly = false;
     private static string _outputFile;
     private static string _exclude = string.Empty;
 
@@ -27,6 +28,8 @@ private static void Main(string[] args)
 
       _recursive = args.Any(a => a == "--recursive");
 
+      _latestOnly = args.Any(a => a == "--latest-only");
+
       _outputFile = args.FirstOrDefault(a => a.StartsWith("--output="))?.Replace("--output=", string.Empty) ?? Path.Combine(_dir, _xmlFileName);
 
       _exclude = args.FirstOrDefault(a => a.StartsWith("--exclude="))?.Replace("--exclude=", string.Empty) ?? string.Empty;
@@ -45,7 +48,7 @@ private static void Main(string[] args)
 
         case var a when (a.Contains("--terminate") || a.Contains("-t")):
           break;
-        
+
         default:
           Console.WriteLine("Press any key to close...");
           Console.ReadKey(true);
@@ -85,12 +88,17 @@ private static void FileChanged(object sender, EventArgs e)
 
     private static void GenerateAtomFeed()
     {
-      var packages = EnumerateFilesSafe(new DirectoryInfo(_dir), "*.vsix", _recursive ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly).Distinct();
-      var filteredPackages = string.IsNullOrEmpty(_exclude) ? packages : packages.Where(f => !f.FullName.Contains(_exclude));
+      var packageFiles = EnumerateFilesSafe(new DirectoryInfo(_dir), "*.vsix", _recursive ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly).Distinct();
+      var filteredPackageFiles = string.IsNullOrEmpty(_exclude) ? packageFiles : packageFiles.Where(f => !f.FullName.Contains(_exclude));
+      var packagesToProcess = filteredPackageFiles.Select(f => ProcessVsix(f.FullName));
+      if (_latestOnly)
+      {
+        packagesToProcess = packagesToProcess.GroupBy(p => p.ID).Select(g => g.OrderByDescending(pkg => Version.Parse(pkg.Version)).First());
+      }
 
       var writer = new FeedWriter(_galleryName);
       string feedUrl = _outputFile;
-      string xml = writer.GetFeed(feedUrl, filteredPackages.Select(f => ProcessVsix(f.FullName)));
+      string xml = writer.GetFeed(feedUrl, packagesToProcess);
 
       File.WriteAllText(feedUrl, xml, Encoding.UTF8);