using Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax;

namespace Microsoft.CodeAnalysis.CSharp.Syntax;

public sealed class DeclarationPatternSyntax : PatternSyntax
{
	private TypeSyntax? type;

	private VariableDesignationSyntax? designation;

	public TypeSyntax Type => ((SyntaxNode)this).GetRedAtZero<TypeSyntax>(ref type);

	public VariableDesignationSyntax Designation => ((SyntaxNode)this).GetRed<VariableDesignationSyntax>(ref designation, 1);

	internal DeclarationPatternSyntax(Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.CSharpSyntaxNode green, SyntaxNode? parent, int position)
		: base(green, parent, position)
	{
	}

	internal override SyntaxNode? GetNodeSlot(int index)
	{
		return (SyntaxNode?)(index switch
		{
			0 => ((SyntaxNode)this).GetRedAtZero<TypeSyntax>(ref type), 
			1 => ((SyntaxNode)this).GetRed<VariableDesignationSyntax>(ref designation, 1), 
			_ => null, 
		});
	}

	internal override SyntaxNode? GetCachedSlot(int index)
	{
		return (SyntaxNode?)(index switch
		{
			0 => type, 
			1 => designation, 
			_ => null, 
		});
	}

	public override void Accept(CSharpSyntaxVisitor visitor)
	{
		visitor.VisitDeclarationPattern(this);
	}

	public override TResult? Accept<TResult>(CSharpSyntaxVisitor<TResult> visitor)
	{
		return visitor.VisitDeclarationPattern(this);
	}

	public DeclarationPatternSyntax Update(TypeSyntax type, VariableDesignationSyntax designation)
	{
		if (type != Type || designation != Designation)
		{
			DeclarationPatternSyntax declarationPatternSyntax = SyntaxFactory.DeclarationPattern(type, designation);
			SyntaxAnnotation[] annotations = ((SyntaxNode)this).GetAnnotations();
			if (annotations == null || annotations.Length == 0)
			{
				return declarationPatternSyntax;
			}
			return declarationPatternSyntax.WithAnnotations(annotations);
		}
		return this;
	}

	public DeclarationPatternSyntax WithType(TypeSyntax type)
	{
		return Update(type, Designation);
	}

	public DeclarationPatternSyntax WithDesignation(VariableDesignationSyntax designation)
	{
		return Update(Type, designation);
	}
}