namespace
{
  //! Return string associated with VRML reader status.
  static const char* getVrmlErrorName (VrmlData_ErrorStatus theStatus)
  {
    switch (theStatus)
    {
      case VrmlData_StatusOK:              return "";
      case VrmlData_EmptyData:             return "EmptyData";
      case VrmlData_UnrecoverableError:    return "UnrecoverableError";
      case VrmlData_GeneralError:          return "GeneralError";
      case VrmlData_EndOfFile:             return "EndOfFile";
      case VrmlData_NotVrmlFile:           return "NotVrmlFile";
      case VrmlData_CannotOpenFile:        return "CannotOpenFile";
      case VrmlData_VrmlFormatError:       return "VrmlFormatError";
      case VrmlData_NumericInputError:     return "NumericInputError";
      case VrmlData_IrrelevantNumber:      return "IrrelevantNumber";
      case VrmlData_BooleanInputError:     return "BooleanInputError";
      case VrmlData_StringInputError:      return "StringInputError";
      case VrmlData_NodeNameUnknown:       return "NodeNameUnknown";
      case VrmlData_NonPositiveSize:       return "NonPositiveSize";
      case VrmlData_ReadUnknownNode:       return "ReadUnknownNode";
      case VrmlData_NonSupportedFeature:   return "NonSupportedFeature";
      case VrmlData_OutputStreamUndefined: return "OutputStreamUndefined";
      case VrmlData_NotImplemented:        return "NotImplemented";
    }
    return "UNKNOWN";
  }

  //! Process sub-shape.
  static void performMeshSubshape (RWMesh_NodeAttributeMap& theAttribMap,
                                   const VrmlData_DataMapOfShapeAppearance& theShapeAppMap,
                                   const TopoDS_Shape& theShape)
  {
    Handle(VrmlData_Appearance) anAppearance;
    if (theShapeAppMap.Find (theShape.TShape(), anAppearance))
    {
      if (!anAppearance.IsNull()
       && !anAppearance->Material().IsNull())
      {
        RWMesh_NodeAttributes aFaceAttribs;
        aFaceAttribs.Style.SetColorSurf (anAppearance->Material()->DiffuseColor());
        theAttribMap.Bind (theShape, aFaceAttribs);
      }
    }

    for (TopoDS_Iterator aSubShapeIter (theShape, true, false); aSubShapeIter.More(); aSubShapeIter.Next())
    {
      performMeshSubshape (theAttribMap, theShapeAppMap, aSubShapeIter.Value());
    }
  }
}

//! The VRML mesh reader.
class MyCafVrmlReader
{
  //! Read the mesh from specified file.
  bool performMesh (const TCollection_AsciiString& theFile,
                                            const Standard_Boolean theToProbe)
  {
    Standard_CLocaleSentry aLocaleSentry;
    std::ifstream aFile;
    OSD_OpenStream (aFile, theFile.ToCString(), std::ios::in | std::ios::binary);
    if (!aFile.is_open()
     || !aFile.good())
    {
      Message::SendFail (TCollection_AsciiString ("File '") + theFile + "' is not found");
      return false;
    }

    if (theToProbe)
    {
      return false; // unsupported
    }

    // determine file location to load associated files
    TCollection_AsciiString aFolder;
    {
      OSD_Path aPath (theFile);
      aPath.SetName ("");
      aPath.SetExtension ("");
      aPath.SystemName (aFolder);
    }

    VrmlData_Scene aScene;
    aScene.SetLinearScale (myUnitFactor);
    aScene.SetVrmlDir (aFolder);
    aScene << aFile;

    VrmlData_DataMapOfShapeAppearance aShapeAppMap;
    TopoDS_Shape aShape = aScene.GetShape (aShapeAppMap);
    if (!aShape.IsNull())
    {
      performMeshSubshape (myAttribMap, aShapeAppMap, aShape);
      myRootShapes.Append (aShape);
    }
    if (aScene.Status() != VrmlData_StatusOK
     || aShape.IsNull())
    {
      Message::SendFail (TCollection_AsciiString ("Error ") + getVrmlErrorName (aScene.Status())
                       + " occurred at line " + aScene.GetLineError()
                       + "\nwhile reading VRML file '" + theFile + "'");
      return false;
    }

    return true;
  }

protected:
  double myUnitFactor;  //!< length unit scale factor

};