//+----------------------------------------------------------------------------+
//| Description:  Magic Set Editor - Program to make Magic (tm) cards          |
//| Copyright:    (C) Twan van Laarhoven and the other MSE developers          |
//| License:      GNU General Public License 2 or later (see file COPYING)     |
//+----------------------------------------------------------------------------+

#pragma once

// ----------------------------------------------------------------------------- : Includes

#include <util/prec.hpp>
#include <util/dynamic_arg.hpp>
#include <cstdint>
#include <atomic>

// ----------------------------------------------------------------------------- : Age

/// Represents the age of a value, higher values are newer
/** Age is counted using a global variable */
class Age {
public:
  typedef uint_fast64_t age_t;

  /// Construct a new age value
  Age() {
    update();
  }
  /// Create a special age
  /** 0: dummy value, used for other purposes
   *  1: before 'beginning of time', the age conceptually just before program start
   *  2..: normal ages
   */
  Age(age_t age) : age(age) {}
  
  /// Update the age to become the newest one
  inline void update() {
    age = ++new_age;
  }
  
  /// Compare two ages, smaller means earlier
  inline bool operator < (Age a) const { return age < a.age; }
  /// Compare two ages
  inline bool operator <= (Age a) const { return age <= a.age; }
  /// Compare two ages
  inline bool operator == (Age a) const { return age == a.age; }
  
  /// A number corresponding to the age
  inline age_t get() const { return age; }
  
private:
  /// This age
  age_t age;
  /// Global age counter, value of the last age created
  static atomic<age_t> new_age;
};


/// Age the object currently being processed was last updated
/** NOTE:
 *  image generating functions have two modes
 *  if last_update_age >  0 they return whether the image is still up to date
 *  if last_update_age == 0 they generate the image
 */
DECLARE_DYNAMIC_ARG(Age::age_t, last_update_age);