rokojori_action_library/Tools/mcp/Routes/WriteSceneFragmentRoute.cs

#if TOOLS

using Godot;

namespace Rokojori.Tools
{
  using Rokojori;

  public static class WriteSceneFragmentRoute
  {
    public static JSONObject ToolDefinition()
    {
      var filePathSchema = new JSONObject();
      filePathSchema.Set( "type", "string" );
      filePathSchema.Set( "description", "res:// path to the scene (.tscn)" );

      var scenePathSchema = new JSONObject();
      scenePathSchema.Set( "type", "array" );
      scenePathSchema.Set( "description", "Child names from the scene root to the node the fragment patches. Empty array = scene root. The node itself must already exist - only its descendants can be newly created." );

      var fragmentSchema = new JSONObject();
      fragmentSchema.Set( "type", "object" );
      fragmentSchema.Set( "description", "Patch data: { properties: {...}, children: { childName: {...} | { \"__remove\": true } } }. Children are keyed by name, omitted children are left untouched." );

      var properties = new JSONObject();
      properties.Set( "filePath", filePathSchema );
      properties.Set( "scenePath", scenePathSchema );
      properties.Set( "sceneFragmentData", fragmentSchema );

      var required = new JSONArray();
      required.Push( "filePath" );
      required.Push( "scenePath" );
      required.Push( "sceneFragmentData" );

      var schema = new JSONObject();
      schema.Set( "type", "object" );
      schema.Set( "properties", properties );
      schema.Set( "required", required );

      var tool = new JSONObject();
      tool.Set( "name", "write_scene_fragment" );
      tool.Set( "description", "Patch a node subtree in a scene file: set properties, add/patch/remove children by name." );
      tool.Set( "inputSchema", schema );

      return tool;
    }

    public static ToolCallOutcome Execute( JSONObject arguments )
    {
      var filePath = JsonUtil.GetStringOrNull( arguments, "filePath" );
      var scenePathArray = arguments != null ? arguments.GetArray( "scenePath" ) : null;
      var fragmentData = arguments != null ? arguments.GetObject( "sceneFragmentData" ) : null;

      if ( string.IsNullOrEmpty( filePath ) )
      {
        return ToolCallOutcome.Error( "Missing required argument: filePath" );
      }

      if ( fragmentData == null )
      {
        return ToolCallOutcome.Error( "Missing required argument: sceneFragmentData" );
      }

      if ( ! ResourceLoader.Exists( filePath, "PackedScene" ) )
      {
        return ToolCallOutcome.Error( "Scene not found: " + filePath );
      }

      var packedScene = ResourceLoader.Load<PackedScene>( filePath );

      if ( packedScene == null )
      {
        return ToolCallOutcome.Error( "Failed to load scene: " + filePath );
      }

      // Plain Instantiate() resolves every property on every node to a concrete value, including
      // ones a node only inherits from an instanced sub-scene. Pack() then has no way to tell
      // "inherited" apart from "actually overridden" and bakes the current value of every property
      // on every instanced node in the whole tree into an explicit override - corrupting unrelated
      // sub-scenes (e.g. a vehicle model) far outside the patched fragment. GenEditState.Main keeps
      // the instance-vs-override bookkeeping alive so Pack() only stores genuine overrides, matching
      // how the editor itself instantiates a scene it's about to re-save as the main edited scene.
      var root = packedScene.Instantiate( PackedScene.GenEditState.Main );

      if ( root == null )
      {
        return ToolCallOutcome.Error( "Failed to instantiate scene: " + filePath );
      }

      var scenePath = ScenePathResolver.ToStringArray( scenePathArray );
      var target = ScenePathResolver.FindNode( root, scenePath );

      if ( target == null )
      {
        root.Free();
        return ToolCallOutcome.Error( "Node not found at scenePath: " + ScenePathResolver.ToRelativePath( scenePath ) );
      }

      ApplyFragment( root, target, fragmentData );

      var packError = packedScene.Pack( root );

      if ( packError != Error.Ok )
      {
        root.Free();
        return ToolCallOutcome.Error( "Failed to pack scene: " + packError );
      }

      var saveError = ResourceSaver.Save( packedScene, filePath );
      root.Free();

      if ( saveError != Error.Ok )
      {
        return ToolCallOutcome.Error( "Failed to save scene: " + saveError );
      }

      var result = new JSONObject();
      result.Set( "filePath", filePath );
      result.Set( "scenePath", ScenePathResolver.ToRelativePath( scenePath ) );

      return ToolCallOutcome.Ok( JSON.Stringify( result ) );
    }

    static void ApplyFragment( Node root, Node target, JSONObject fragmentData )
    {
      var properties = fragmentData.GetObject( "properties" );

      if ( properties != null )
      {
        PropertyReflection.ApplyFromJson( target, properties );
      }

      var children = fragmentData.GetObject( "children" );

      if ( children == null )
      {
        return;
      }

      for ( var i = 0; i < children.keys.Count; i++ )
      {
        var childName = children.keys[ i ];
        var childData = children.values[ i ].AsObject();

        if ( childData == null )
        {
          continue;
        }

        var existingChild = FindDirectChild( target, childName );

        if ( childData.Contains( "__remove" ) )
        {
          if ( existingChild != null )
          {
            target.RemoveChild( existingChild );
            existingChild.Free();
          }

          continue;
        }

        if ( existingChild != null )
        {
          ApplyFragment( root, existingChild, childData );
          continue;
        }

        var typeName = JsonUtil.GetStringOrNull( childData, "type" );

        if ( string.IsNullOrEmpty( typeName ) )
        {
          RJLog.Error( "MCP WriteSceneFragment: new child needs a 'type'", childName );
          continue;
        }

        if ( ! ClassDB.ClassExists( typeName ) )
        {
          RJLog.Error( "MCP WriteSceneFragment: unknown class", typeName );
          continue;
        }

        var newNode = ClassDB.Instantiate( typeName ).As<Node>();

        if ( newNode == null )
        {
          RJLog.Error( "MCP WriteSceneFragment: class is not a Node", typeName );
          continue;
        }

        newNode.Name = childName;
        target.AddChild( newNode );
        newNode.Owner = root;

        ApplyFragment( root, newNode, childData );
      }
    }

    static Node FindDirectChild( Node parent, string name )
    {
      var count = parent.GetChildCount( false );

      for ( var i = 0; i < count; i++ )
      {
        var child = parent.GetChild( i, false );

        if ( child.Name.ToString() == name )
        {
          return child;
        }
      }

      return null;
    }
  }
}

#endif