// Created by: DAUTRY Philippe
// Copyright (c) 1997-1999 Matra Datavision
// Copyright (c) 1999-2014 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#ifndef _TDocStd_XLink_HeaderFile
#define _TDocStd_XLink_HeaderFile

#include "Standard.hxx"

#include "TCollection_AsciiString.hxx"
#include "TDocStd_XLinkPtr.hxx"
#include "TDF_Attribute.hxx"
#include "Standard_OStream.hxx"
class TDF_Label;
class TDF_Reference;
class Standard_GUID;
class TDF_AttributeDelta;
class TDF_RelocationTable;

//! An attribute to store the path and the entry of
//! external links.
//! These refer from one data structure to a data
//! structure in another document.
class TDocStd_XLink : public TDF_Attribute
{

public:
  //! Sets an empty external reference, at the label aLabel.
  Standard_EXPORT static occ::handle<TDocStd_XLink> Set(const TDF_Label& atLabel);

  //! Initializes fields.
  Standard_EXPORT TDocStd_XLink();

  //! Updates the data referenced in this external link attribute.
  Standard_EXPORT occ::handle<TDF_Reference> Update();

  //! Returns the ID of the attribute.
  Standard_EXPORT const Standard_GUID& ID() const override;

  //! Returns the GUID for external links.
  Standard_EXPORT static const Standard_GUID& GetID();

  //! Sets the name aDocEntry for the external
  //! document in this external link attribute.
  Standard_EXPORT void DocumentEntry(const TCollection_AsciiString& aDocEntry);

  //! Returns the contents of the document identified by aDocEntry.
  //! aDocEntry provides external data to this external link attribute.
  Standard_EXPORT const TCollection_AsciiString& DocumentEntry() const;

  //! Sets the label entry for this external link attribute with the label aLabel.
  //! aLabel pilots the importation of data from the document entry.
  Standard_EXPORT void LabelEntry(const TDF_Label& aLabel);

  //! Sets the label entry for this external link attribute
  //! as a document identified by aLabEntry.
  Standard_EXPORT void LabelEntry(const TCollection_AsciiString& aLabEntry);

  //! Returns the contents of the field <myLabelEntry>.
  Standard_EXPORT const TCollection_AsciiString& LabelEntry() const;

  //! Updates the XLinkRoot attribute by adding <me>
  //! to its list.
  Standard_EXPORT void AfterAddition() override;

  //! Updates the XLinkRoot attribute by removing <me>
  //! from its list.
  Standard_EXPORT void BeforeRemoval() override;

  //! Something to do before applying <anAttDelta>.
  Standard_EXPORT bool BeforeUndo(const occ::handle<TDF_AttributeDelta>& anAttDelta,
                                  const bool                             forceIt = false) override;

  //! Something to do after applying <anAttDelta>.
  Standard_EXPORT bool AfterUndo(const occ::handle<TDF_AttributeDelta>& anAttDelta,
                                 const bool                             forceIt = false) override;

  //! Returns a null handle. Raise always for it is
  //! nonsense to use this method.
  Standard_EXPORT occ::handle<TDF_Attribute> BackupCopy() const override;

  //! Does nothing.
  Standard_EXPORT void Restore(const occ::handle<TDF_Attribute>& anAttribute) override;

  //! Returns a null handle.
  Standard_EXPORT occ::handle<TDF_Attribute> NewEmpty() const override;

  //! Does nothing.
  Standard_EXPORT void Paste(
    const occ::handle<TDF_Attribute>&       intoAttribute,
    const occ::handle<TDF_RelocationTable>& aRelocationTable) const override;

  //! Dumps the attribute on <aStream>.
  Standard_EXPORT Standard_OStream& Dump(Standard_OStream& anOS) const override;

  friend class TDocStd_XLinkRoot;
  friend class TDocStd_XLinkIterator;

  DEFINE_STANDARD_RTTIEXT(TDocStd_XLink, TDF_Attribute)

private:
  //! Sets the field <myNext> with <anXLinkPtr>.
  void Next(const TDocStd_XLinkPtr& anXLinkPtr);

  //! Returns the contents of the field <myNext>.
  TDocStd_XLinkPtr Next() const;

  TCollection_AsciiString myDocEntry;
  TCollection_AsciiString myLabelEntry;
  TDocStd_XLinkPtr        myNext;
};

#include "TDocStd_XLink.lxx"

#endif // _TDocStd_XLink_HeaderFile