Fix First call.

Contentless/NuGetHelper.cs

@@ -0,0 +1,15 @@
+using NuGet.Configuration;
+
+namespace Contentless;
+
+public class NuGetHelper
+{
+    private readonly ISettings _settings;
+    
+    public NuGetHelper(string projectFolder)
+    {
+        _settings = Settings.LoadDefaultSettings(projectFolder);
+    }
+
+    public string PackageFolder => SettingsUtility.GetGlobalPackagesFolder(_settings);
+}

Contentless/Program.cs

@@ -7,7 +7,6 @@ using System.Text.RegularExpressions;
 using Microsoft.Build.Construction;
 using Microsoft.Xna.Framework.Content.Pipeline;
 using Newtonsoft.Json;
-using NuGet.Configuration;
 
 namespace Contentless;
 
@@ -45,52 +44,29 @@ public static class Program {
         var overrides = Program.GetOverrides(config.Overrides).ToArray();
 
         var referencesVersions = config.References.ToDictionary(x => x, x => (string)null, StringComparer.OrdinalIgnoreCase);
-        if (config.References.Length > 0)
-        {
-            if (args.Length < 2) {
-                Console.WriteLine("You supplied references but there is no project file, this isn't compatible. Please specify the full path of project file, if you want to sync references");
-                return;
+        if (config.References.Length > 0) {
+            if (args.Length > 1) {
+                ExtractVersions(args[1], referencesVersions);
+                _nuGetHelper = new NuGetHelper(Path.GetDirectoryName(args[1]));
             }
-            var csprojPath = args[1];
-            Console.WriteLine($"Using project file {csprojPath}");
-            var projectRootElement = ProjectRootElement.Open(csprojPath);
-            foreach (var property in projectRootElement.AllChildren.Where(x => x.ElementName == "PackageReference").Select(x => x as ProjectItemElement))
-            {
-                var libraryName = property.Include;
-                var version = (property.Children.First() as ProjectMetadataElement).Value;
-                if (referencesVersions.Keys.Contains(libraryName))
-                {
-                    referencesVersions[libraryName] = version;
-                    Console.WriteLine($"Found library version for sync: {libraryName}, {version}");
-                }
-            }
-
-            foreach (var library in referencesVersions)
-                if (library.Value is null)
-                {
-                    Console.WriteLine($"Unable to find library {library.Key}");
-                    return;
-                }
+            else
+                Console.Error.WriteLine("You supplied references but there is no project file, this isn't compatible. Please specify the full path of project file, if you want to sync references");
         }
         
+        const string ReferenceHeader = "/reference:";
         var changed = false;
         var referencesSyncs = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
         // load any references to be able to include custom content types as well
-        for (int i = 0; i < content.Count; i++)
-        {
-            const string ReferenceHeader = "/reference:";
-            
+        for (int i = 0; i < content.Count; i++) {
             var line = content[i];
             if (!line.StartsWith(ReferenceHeader))
                 continue;
             var reference = line.Substring(ReferenceHeader.Length);
             var libraryName = Path.GetFileName(reference)[..^4];
 
-            if (referencesVersions.Keys.Contains(libraryName))
-            {
-                var fullLibraryPath = CalculateFullPathToLibrary(libraryName, referencesVersions[libraryName]);
-                if (reference != fullLibraryPath)
-                {
+            if (referencesVersions.TryGetValue(libraryName, out var version) && version is not null) {
+                var fullLibraryPath = CalculateFullPathToLibrary(libraryName, version);
+                if (reference != fullLibraryPath) {
                     Console.WriteLine($"Changing library reference from {reference} to {fullLibraryPath}");
                     reference = fullLibraryPath;
                     content[i] = ReferenceHeader + fullLibraryPath;
@@ -103,20 +79,37 @@ public static class Program {
             }
             
             var refPath = Path.GetFullPath(Path.Combine(contentFile.DirectoryName, reference));
-            try {
-                Assembly.LoadFrom(refPath);
-                Console.WriteLine($"Using reference {refPath}");
-            } catch (Exception e) {
-                Console.WriteLine($"Error loading reference {refPath}: {e}");
-            }
+            SafeAssemblyLoad(refPath);
         }
 
         // check references not in .mgcb now
+        var referencesLastIndex = 0;
+        // find place where I can add new reference
+        for (int i = 0; i < content.Count; i++)
+        {
+            var line = content[i];
+            if (line.StartsWith(ReferenceHeader))
+                referencesLastIndex = i + 1;
+            else if (line.StartsWith("/importer:") || line.StartsWith("/processor:") || line.StartsWith("/build:") ||
+                     line.Contains("-- Content --")) {
+                if (referencesLastIndex == 0)
+                    referencesLastIndex = i;
+                break;
+            }
+        }
         foreach (var reference in referencesVersions)
-            if (!referencesSyncs.Contains(reference.Key))
-            {
-                Console.WriteLine($"Please, add reference for {reference.Key} in .mgcb file or remove it from Contentless! Reference was skipped!");
-                return;
+            if (!referencesSyncs.Contains(reference.Key) && reference.Value is not null) {
+                try {
+                    var path = CalculateFullPathToLibrary(reference.Key, reference.Value);
+                    content.Insert(referencesLastIndex++, ReferenceHeader + path);
+                    changed = true;
+                    SafeAssemblyLoad(path);
+                    Console.WriteLine($"Adding reference for {path} in .mgcb");
+                }
+                catch (Exception e)
+                {
+                    Console.Error.WriteLine($"Error adding library {reference.Key} in .mgcb: {e}");
+                }
             }
         
 
@@ -204,10 +197,43 @@ public static class Program {
         Console.Write("Done");
     }
 
+    private static void SafeAssemblyLoad(string refPath)
+    {
+        try {
+            Assembly.LoadFrom(refPath);
+            Console.WriteLine($"Using reference {refPath}");
+        } catch (Exception e) {
+            Console.WriteLine($"Error loading reference {refPath}: {e}");
+        }
+    }
+
+    private static void ExtractVersions(string csprojPath, Dictionary<string, string> referencesVersions)
+    {
+        Console.WriteLine($"Using project file {csprojPath}");
+        var projectRootElement = ProjectRootElement.Open(csprojPath);
+        foreach (var property in projectRootElement.AllChildren.Where(x => x.ElementName == "PackageReference").Select(x => x as ProjectItemElement))
+        {
+            var libraryName = property.Include;
+            if (property.Children.FirstOrDefault(x => x.ElementName == "Version") is not ProjectMetadataElement versionElement)
+                continue;
+            var version = versionElement.Value;
+            if (referencesVersions.Keys.Contains(libraryName))
+            {
+                referencesVersions[libraryName] = version;
+                Console.WriteLine($"Found library version for sync: {libraryName}, {version}");
+            }
+        }
+
+        foreach (var library in referencesVersions)
+            if (library.Value is null) 
+                Console.Error.WriteLine($"Unable to find library {library.Key} in .csproj");
+    }
+
+    private static NuGetHelper _nuGetHelper;
+
     private static string CalculateFullPathToLibrary(string libraryName, string referencesVersion)
     {
-        var settings = Settings.LoadDefaultSettings(null);
-        return Path.Combine(SettingsUtility.GetGlobalPackagesFolder(settings), libraryName.ToLower(), referencesVersion, "tools", libraryName + ".dll");
+        return Path.Combine(_nuGetHelper.PackageFolder, libraryName.ToLower(), referencesVersion, "tools", libraryName + ".dll");
     }
 
     private static (List<ImporterInfo>, List<string>) GetContentData() {

Test/NuGet.Config

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+    <packageSources>
+        <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
+        <add key="lithiumtoast" value="https://www.myget.org/F/lithiumtoast/api/v3/index.json" />
+    </packageSources>
+</configuration>