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

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

#pragma once

#include "cmConfigure.h" // IWYU pragma: keep

#include <map>

#include <memory>

#include <string>

#include <vector>

class cmMakefile;

/** \class cmVariableWatch

 * \brief Helper class for watching of variable accesses.

 *

 * Calls function when variable is accessed

 */

class cmVariableWatch

{

public:

  /**

   * Different access types.

   */

  enum AccessType : unsigned

  {

    VARIABLE_READ_ACCESS,

    UNKNOWN_VARIABLE_READ_ACCESS,

    UNKNOWN_VARIABLE_DEFINED_ACCESS,

    VARIABLE_MODIFIED_ACCESS,

    VARIABLE_REMOVED_ACCESS,

    NO_ACCESS

  };

  using WatchMethod = void (*)(std::string const&, AccessType, void*,

                               char const*, cmMakefile const*);

  using DeleteData = void (*)(void*);

  cmVariableWatch();

  ~cmVariableWatch();

  /**

   * Add watch to the variable

   */

  bool AddWatch(std::string const& variable, WatchMethod method,

                void* client_data = nullptr, DeleteData delete_data = nullptr);

  void RemoveWatch(std::string const& variable, WatchMethod method,

                   void* client_data = nullptr);

  /**

   * This method is called when variable is accessed

   */

  bool VariableAccessed(std::string const& variable, AccessType accessType,

                        char const* newValue, cmMakefile const* mf) const;

  /**

   * Return the access as string

   */

  static std::string const& GetAccessAsString(AccessType accessType);

protected:

  struct Pair

  {

    WatchMethod Method = nullptr;

    void* ClientData = nullptr;

    DeleteData DeleteDataCall = nullptr;

    ~Pair()

    {

      if (this->DeleteDataCall && this->ClientData) {

        this->DeleteDataCall(this->ClientData);

      }

    }

    Pair() = default;

    Pair(Pair const&) = delete;

    Pair& operator=(Pair const&) = delete;

  };

  using VectorOfPairs = std::vector<std::shared_ptr<Pair>>;

  using StringToVectorOfPairs = std::map<std::string, VectorOfPairs>;

  StringToVectorOfPairs WatchMap;

};