Updates a nuspec to reflect the references in the csproj

sync nuspec with references.cs

foreach (var csproj in Directory.GetFiles(@"C:\Git\_InternalTools\Nephele", "*.csproj", SearchOption.AllDirectories))
{
	var nuspecFileInfo = new FileInfo(Path.ChangeExtension(csproj, ".nuspec"));
	if (!nuspecFileInfo.Exists)
		continue;

	Console.WriteLine($"Inspecting {nuspecFileInfo.Name}");
	var xNuspec = XDocument.Load(nuspecFileInfo.FullName);
	var xMetaData = xNuspec.XPathSelectElement("package/metadata");
	var xDependencies = xMetaData.XPathSelectElement("dependencies");
	bool dirty = false;

	var xcsProj = XDocument.Load(csproj);
	var xPackageReferences = xcsProj.XPathSelectElements("/Project/ItemGroup/PackageReference[not(PrivateAssets[text()='all'])]");
	var xProjectReferences = xcsProj.XPathSelectElements("/Project/ItemGroup/ProjectReference");
	if (xPackageReferences.Any() || xProjectReferences.Any())
	{
		if (xDependencies == null)
		{
			xDependencies = new XElement("dependencies");
			xMetaData.Add(xDependencies);
			Console.WriteLine("> Added dependencies node");
			dirty = true;
		}

		foreach (var xReference in xPackageReferences)
		{
			string name = (string )xReference.Attribute("Include");
			string version = (string )xReference.Attribute("Version");
			
			var xDependency = xDependencies.XPathSelectElement($"dependency[@id='{name}']");
			if (xDependency == null)
			{
				xDependency = new XElement("dependency", new XAttribute("id", name), new XAttribute("version", version));
				xDependencies.Add(xDependency);

				Console.WriteLine($"> Added dependency {name} {version}");
				dirty = true;
				continue;
			}

			var xVersion = xDependency.Attribute("version");
			if ((string)xVersion != version)
			{
				xVersion.Value = version;

				Console.WriteLine($"> Updated dependency {name} {version}");
				dirty = true;
			}
		}

		foreach (var xReference in xProjectReferences)
		{
			var internalNuspec = Path.ChangeExtension(Path.Combine(Path.GetDirectoryName(csproj), (string)xReference.Attribute("Include")), ".nuspec");
			if (!File.Exists(internalNuspec))
			{
				continue;
			}
			
			string name = System.IO.Path.GetFileNameWithoutExtension((string)xReference.Attribute("Include"));

			var xDependency = xDependencies.XPathSelectElement($"dependency[@id='{name}']");
			if (xDependency == null)
			{
				xDependency = new XElement("dependency", new XAttribute("id", name), new XAttribute("version", "$version$"));
				xDependencies.Add(xDependency);

				Console.WriteLine($"> Added internal dependency {name}");
				dirty = true;
				continue;
			}

			var xVersion = xDependency.Attribute("version");
			if ((string)xVersion != "$version$")
			{
				xVersion.Value = "$version$";

				Console.WriteLine($"> Updated dependency {name} to internal");
				dirty = true;
			}
		}
	}

	bool IsPackageReference(string name, string version) => xcsProj.XPathSelectElement($"/Project/ItemGroup/PackageReference[@Include='{name}' and @Version='{version}' and not(PrivateAssets[text()='all'])]") != null;
	bool IsProjectReference(string name, string version) => version == "$version$" 
			&& xcsProj.XPathSelectElements($"/Project/ItemGroup/ProjectReference")
				.Select(x => (string)x.Attribute("Include"))
				.Select(x => System.IO.Path.GetFileNameWithoutExtension(x))
				.Contains(name, StringComparer.OrdinalIgnoreCase);
	
	if (xDependencies != null)
	{
		foreach (var xDependency in xDependencies.XPathSelectElements("dependency").ToList())
		{
			string name = (string)xDependency.Attribute("id");
			string version = (string)xDependency.Attribute("version");

			if (IsPackageReference(name, version) || IsProjectReference(name, version))
				continue;

			Console.WriteLine($"> Removed dependency {name} {version}");

			xDependency.Remove();
			dirty = true;
		}
		
		if (!xDependencies.Elements().Any())
		{
			xDependencies.Remove();

			Console.WriteLine($"> Dropped all dependencies");
			dirty = true;
		}
	}

	if (dirty)
	{
		xNuspec.Save(nuspecFileInfo.FullName);
		Console.WriteLine($"Updated {nuspecFileInfo.FullName}");
	}
}