Sorting visual studio project files

gistfile1.cs

static XNamespace ns = "http://schemas.microsoft.com/developer/msbuild/2003";
static XName ItemGroup = ns + "ItemGroup";
static XName Reference = ns + "Reference";
static XName ProjectReference = ns + "ProjectReference";
static XName Condition = "Condition";
static XName Include = "Include";

void Main(string[] args)
{
    if (args.Length != 1) {
        Console.WriteLine ("Syntax: lprun SortProject.linq Core\\Core.csproj");
        return;
    }

    XDocument doc = XDocument.Load (args [0]);
    var root = doc.Root;

    var groups = root
        .Elements (ItemGroup)
        .Where (group => !group.HasAttributes)
        .ToList ();

    foreach (var g in groups) {
        g.Remove ();
    }
    
    var items = GroupItems (groups.SelectMany (g => g.Elements ()));
    root.Add (GroupItems (items.Elements (Reference)));
    root.Add (GroupItems (items.Elements (ProjectReference)));
    root.Add (GroupItems (items.Elements ()));
    doc.Save (args [0]);
}

private XElement GroupItems (IEnumerable<XElement> elements)
{
    var container = new XElement (ItemGroup);
    MoveElements (container, elements);
    return container;
}

private void MoveElements (XElement container, IEnumerable<XElement> elements)
{
    foreach (var element in elements.OrderBy (e => e, new ItemComparer ()).ToList ()) {
        element.Remove ();
        container.Add (element);
    }
}

class ItemComparer : IComparer<XElement>
{
    public int Compare (XElement e1, XElement e2)
    {
        var a1 = e1.Attribute (Include);
        var a2 = e2.Attribute (Include);
        
        if (a1 == null && a2 == null) return 0;
        if (a1 == null) return 1;
        if (a2 == null) return -1;
        
        var v1 = a1.Value;
        var v2 = a2.Value;
        
        try {
            var d1 = Path.GetDirectoryName (v1);
            var d2 = Path.GetDirectoryName (v2);
            
            var result = string.Compare (d1, d2, StringComparison.OrdinalIgnoreCase);
            if (result != 0) return result;
            
            var f1 = Path.GetFileName (v1);
            var f2 = Path.GetFileName (v2);
            
            result = string.Compare (f1, f2, StringComparison.OrdinalIgnoreCase);
            return result;
        } catch {
            return string.Compare (v1, v2, StringComparison.OrdinalIgnoreCase);
        }
    }
}