// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Collections.Generic;
using System.Threading;
using Microsoft.AspNetCore.Razor.Language.Intermediate;
 
namespace Microsoft.AspNetCore.Razor.Language.Extensions;
 
internal sealed class DesignTimeDirectivePass : IntermediateNodePassBase, IRazorDirectiveClassifierPass
{
    internal const string DesignTimeVariable = "__o";
 
    // This needs to run after other directive classifiers. Any DirectiveToken that is not removed
    // by the previous classifiers will have auto-generated design time support.
    public override int Order => DefaultFeatureOrder;
 
    protected override void ExecuteCore(
        RazorCodeDocument codeDocument,
        DocumentIntermediateNode documentNode,
        CancellationToken cancellationToken)
    {
        // Only supports design time. This pass rewrites directives so they will have the right design time
        // behavior and would break things if it ran for runtime.
        if (!documentNode.Options.DesignTime)
        {
            return;
        }
 
        var walker = new DesignTimeHelperWalker();
        walker.VisitDocument(documentNode);
    }
 
    internal class DesignTimeHelperWalker : IntermediateNodeWalker
    {
        private readonly Stack<DesignTimeDirectiveIntermediateNode> _directiveNodes = new();
 
        public override void VisitClassDeclaration(ClassDeclarationIntermediateNode node)
        {
            node.Children.Insert(0, new CSharpCodeIntermediateNode()
            {
                Children = { IntermediateNodeFactory.CSharpToken("#pragma warning disable 0414") }
            });
 
            node.Children.Insert(1, new CSharpCodeIntermediateNode()
            {
                Children = { IntermediateNodeFactory.CSharpToken($"private static object {DesignTimeVariable} = null;") }
            });
 
            node.Children.Insert(2, new CSharpCodeIntermediateNode()
            {
                Children = { IntermediateNodeFactory.CSharpToken("#pragma warning restore 0414") }
            });
 
            _directiveNodes.Push(new DesignTimeDirectiveIntermediateNode());
 
            VisitDefault(node);
 
            node.Children.Insert(0, _directiveNodes.Pop());
        }
 
        public override void VisitDirectiveToken(DirectiveTokenIntermediateNode node)
        {
            _directiveNodes.Peek().Children.Add(node);
        }
    }
}