/*!
 * @file class_id.h
 * @brief Definition of a dynamically allocating ClassID
 *
 */

#ifndef _CLASS_ID_H
#define _CLASS_ID_H

#include <string>

class ObjectListBase;

//! A class to dynamically allocate ClassID's and to support a isA operator
/**
 * A ClassID can only be aquired over a ObjectList,
 * thus enabling the developer to have permanent access to the correct ID and ClassName
 *
 * The Idea behind this concept is, that storing a ClassID that changes its internal state
 * all ClassID's will be updated correctly.
 *
 * Since the Existance of any ObjectList is a requirement during the working process all
 * ID's should reference a valid ID and ClassName
 */
class ClassID
{
public:
  ClassID();
  ClassID(const ObjectListBase* const id);
  /// the copy constructor is also defined implicitely.

  /** @returns A constant reference to the ID. */
  const int& id() const { return *_id; };
  /** @returns A constant reference to the Name. */
  const std::string& name() const { return *_name; };

  /** @param id the id to compare @returns true on match (match is same ID) @brief compares two id's */
  bool operator==(const ClassID& id) const { return *_id == *id._id /* || _name == id._name */; };
  /** @param id the id to compare @returns true on match (match is same ID) @brief compares two id's */
  bool operator==(int id) const { return *_id == id; };
  /** @param name the id to compare @returns true on match (match is same Name) @brief compares an ID with a ClassName */
  bool operator==(const std::string& name) const { return *_name == name; };
  /** @param id the id to compare @returns false on match (match is same ID) @brief compares two id's */
  bool operator!=(const ClassID& id) const { return *_id != *id._id /* && _name != id._name*/;  };
  /** @param id the id to compare @returns false on match (match is same ID) @brief compares two id's */
  bool operator!=(int id) const { return *_id != id; };
  /** @param name the id to compare @returns false on match (match is same Name) @brief compares an ID with a ClassName */
  bool operator!=(const std::string& name) const { return *_name != name; };

private:
  const int*                _id;           //!< A pointer to the ID of the ClassID.
  const std::string*        _name;         //!< A pointer to the Name of the ClassID.
};

//! A NullClass. This is the Null of the ClassID.
/**
 * implemented as a Class id can be used to reference NullObjects.
 */
class NullClass
{
public:
  /** @returns the NullClass' ID. */
  static const ClassID& staticClassID() { return NullClass::_classID; }
  /** @param id the ID to acquire @param name the name to acquire @brief acquires the ID of this Class */
  static void acquireID(const int*& id, const std::string*& name) { id = &_nullID; name = &_nullName; };

private:
  NullClass() {}; //!< The Default Constructor is hidden from the User.

private:
  static ClassID            _classID;      //!< The NullClass' ID
  static const std::string  _nullName;     //!< The NullClass' Name ("NullClass")
  static int                _nullID;       //!< The NullClass' ID
};

#endif /* _CLASS_ID_H */