Avalonia/src/tools/Avalonia.Generators/Common/XamlXViewResolver.cs

using System;
using System.Collections.Generic;
using System.Linq;
using Avalonia.Generators.Common.Domain;
using Avalonia.Generators.Compiler;
using XamlX;
using XamlX.Ast;
using XamlX.Parsers;

namespace Avalonia.Generators.Common;

internal class XamlXViewResolver : IViewResolver, IXamlAstVisitor
{
    private readonly RoslynTypeSystem _typeSystem;
    private readonly MiniCompiler _compiler;
    private readonly Action<Exception>? _onUnhandledError;

    private ResolvedView? _resolvedClass;
    private XamlDocument? _xaml;

    public XamlXViewResolver(
        RoslynTypeSystem typeSystem,
        MiniCompiler compiler,
        Action<Exception>? onUnhandledError = null)
    {
        _onUnhandledError = onUnhandledError;
        _typeSystem = typeSystem;
        _compiler = compiler;
    }

    public ResolvedView? ResolveView(string xaml)
    {
        try
        {
            _resolvedClass = null;
            _xaml = XDocumentXamlParser.Parse(xaml, new Dictionary<string, string>
            {
                {XamlNamespaces.Blend2008, XamlNamespaces.Blend2008}
            });

            _compiler.Transform(_xaml);
            _xaml.Root.Visit(this);
            _xaml.Root.VisitChildren(this);
            return _resolvedClass;
        }
        catch (Exception exception)
        {
            _onUnhandledError?.Invoke(exception);
            return null;
        }
    }
    
    IXamlAstNode IXamlAstVisitor.Visit(IXamlAstNode node)
    {
        if (node is not XamlAstObjectNode objectNode)
            return node;

        foreach (var child in objectNode.Children)
        {
            if (child is XamlAstXmlDirective directive &&
                directive.Name == "Class" &&
                directive.Namespace == XamlNamespaces.Xaml2006 &&
                directive.Values[0] is XamlAstTextNode text)
            {
                var split = text.Text.Split('.');
                var nameSpace = string.Join(".", split.Take(split.Length - 1));
                var className = split.Last();

                var clrType = objectNode.Type.GetClrType();
                _resolvedClass = new ResolvedView(className, clrType, nameSpace, _xaml!)
                {
                    IsStyledElement = clrType.IsAvaloniaStyledElement(),
                    HasClass = _typeSystem.FindType(text.Text) is not null
                };
                return node;
            }
        }

        return node;
    }

    void IXamlAstVisitor.Push(IXamlAstNode node) { }

    void IXamlAstVisitor.Pop() { }
}