using System.Collections;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using System.Text;

using System.Globalization;
using Godot;
using System;
using System.Reflection;

namespace Rokojori;


public class ASTWalker:TreeWalker<ASTNode>
{
  public static readonly ASTWalker instance = new ASTWalker(); 

  public override ASTNode Parent( ASTNode node )
  {
    return node?.parent;
  }
  
  public override ASTNode ChildAt( ASTNode node, int index )
  {
    if ( node == null || index < 0 || index >= node.children.Count  )
    {
      return null;
    }

    return node.children[ index ];
  }
  
  public override int NumChildren( ASTNode node )
  {
    return node?.children.Count ?? 0;
  }
}

public class ASTReferenceWalker:TreeWalker<ASTNode>
{
  public override ASTNode Parent( ASTNode node )
  {
    return node?.parent;
  }
  
  public override int NumChildren( ASTNode node )
  {
    if ( node == null )
    {
      return 0;
    }

    if ( node is ASTFileRoot || node is ASTNodeList )
    {
      return node.children.Count;
    } 

    if ( node is SeparatedSequenceExpression se )
    {
      return se.GetExpressions().Count;
    }

    GrabInfo( node );
    return _typeFieldInfos[ node.GetType() ].Count;
  }

  public override ASTNode ChildAt( ASTNode node, int index )
  {
    if ( node == null || index < 0 || index >= node.children.Count  )
    {
      return null;
    }

    if ( node is ASTFileRoot || node is ASTNodeList )
    {
      return node.children[ index ];
    }

    if ( node is SeparatedSequenceExpression se )
    {
      return se.GetExpressions()[ index ];
    }

    GrabInfo( node );
    var fieldInfos = _typeFieldInfos[ node.GetType() ];
    return fieldInfos[ index ].GetValue( node ) as ASTNode;
  }

  public string GetParentReferenceName( ASTNode node )
  {
    var parent = Parent( node );

    if ( parent == null )
    {
      return "";
    }

    
    var index = ChildIndexOf( node );

    return GetChildReferenceName( parent, index );
  }

  public string GetChildReferenceName( ASTNode node, int index )
  {
    if ( node is ASTFileRoot || node is ASTNodeList || node is SeparatedSequenceExpression )
    {
      return index + "";
    }

    GrabInfo( node );

    var fieldInfos = _typeFieldInfos[ node.GetType() ]; 

    return fieldInfos[ index ].Name;
  }

  Dictionary<Type,List<FieldInfo>> _typeFieldInfos = new Dictionary<Type, List<FieldInfo>>();
  
  void GrabInfo( ASTNode node )
  {
    if ( node == null )
    {
      return;
    }

    var type = node.GetType();

    if ( _typeFieldInfos.ContainsKey( type ) )
    {
      return;
    }

    _typeFieldInfos[ type ] = ReflectionHelper.GetFieldInfosOfType<ASTNode>( node );

    
  }

  
}