/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying

   file LICENSE.rst or https://cmake.org/licensing for details.  */

#pragma once

#include <map>

#include <set>

#include <string>

#include <utility>

#include "cmLinkItem.h"

class cmGeneratorTarget;

/** \class cmLinkItemGraphVisitor

 * \brief Visits a graph of linked items.

 *

 * Allows to visit items and dependency links (direct and indirect) between

 * those items.

 * This abstract class takes care of the graph traversal, making sure that:

 *   - it terminates even in the presence of cycles;

 *   - it visits every object once (and only once);

 *   - it visits the objects in the same order every time.

 *

 * Children classes only have to implement OnItem() etc. to handle whatever

 * logic they care about.

 */

class cmLinkItemGraphVisitor

{

public:

  virtual ~cmLinkItemGraphVisitor() = default;

  virtual void VisitGraph(std::string const& name) = 0;

  void VisitItem(cmLinkItem const& item);

protected:

  enum class DependencyType

  {

    LinkInterface,

    LinkPublic,

    LinkPrivate,

    Object,

    Utility

  };

  virtual void OnItem(cmLinkItem const& item) = 0;

  virtual void OnDirectLink(cmLinkItem const& depender,

                            cmLinkItem const& dependee, DependencyType dt) = 0;

  virtual void OnIndirectLink(cmLinkItem const& depender,

                              cmLinkItem const& dependee) = 0;

private:

  std::set<std::string> VisitedItems;

  std::set<std::pair<std::string, std::string>> VisitedLinks;

  void VisitLinks(cmLinkItem const& item, cmLinkItem const& rootItem);

  void VisitLinks(cmLinkItem const& item, cmLinkItem const& rootItem,

                  std::string const& config);

  using Dependency = std::pair<DependencyType, cmLinkItem>;

  using DependencyMap = std::map<std::string, Dependency>;

  bool ItemVisited(cmLinkItem const& item);

  bool LinkVisited(cmLinkItem const& depender, cmLinkItem const& dependee);

  static void GetDependencies(cmGeneratorTarget const& target,

                              std::string const& config,

                              DependencyMap& dependencies);

};