/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
   file Copyright.txt or https://cmake.org/licensing for details.  */
#ifndef cmVariableWatch_h
#define cmVariableWatch_h

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

#include <map>
#include <memory>  // IWYU pragma: keep
#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:
    typedef void (*WatchMethod)(const std::string& variable, int access_type,
                                void* client_data, const char* newValue,
                                const cmMakefile* mf);
    typedef void (*DeleteData)(void* client_data);

    cmVariableWatch();
    ~cmVariableWatch();

    /**
     * Add watch to the variable
     */
    bool AddWatch(const std::string& variable, WatchMethod method,
                  void*      client_data = nullptr,
                  DeleteData delete_data = nullptr);
    void RemoveWatch(const std::string& variable, WatchMethod method,
                     void* client_data = nullptr);

    /**
     * This method is called when variable is accessed
     */
    bool VariableAccessed(const std::string& variable, int access_type,
                          const char* newValue, const cmMakefile* mf) const;

    /**
     * Different access types.
     */
    enum
    {
        VARIABLE_READ_ACCESS = 0,
        UNKNOWN_VARIABLE_READ_ACCESS,
        UNKNOWN_VARIABLE_DEFINED_ACCESS,
        VARIABLE_MODIFIED_ACCESS,
        VARIABLE_REMOVED_ACCESS,
        NO_ACCESS
    };

    /**
     * Return the access as string
     */
    static const char* GetAccessAsString(int access_type);

protected:
    struct Pair
    {
        WatchMethod Method;
        void*       ClientData;
        DeleteData  DeleteDataCall;
        Pair()
        : Method(nullptr)
        , ClientData(nullptr)
        , DeleteDataCall(nullptr)
        {}
        ~Pair()
        {
            if(this->DeleteDataCall && this->ClientData)
            {
                this->DeleteDataCall(this->ClientData);
            }
        }
    };

    typedef std::vector<std::shared_ptr<Pair>>   VectorOfPairs;
    typedef std::map<std::string, VectorOfPairs> StringToVectorOfPairs;

    StringToVectorOfPairs WatchMap;
};

#endif
