//+----------------------------------------------------------------------------+
//| 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/reflect.hpp>

// ----------------------------------------------------------------------------- : Defaultable

/// A value that can also be in a 'default' state.
/** TODO: Defaultable is automatically also Aged
 */
template <typename T>
class Defaultable {
public:
  inline Defaultable()                             :           is_default(true)  {}
  inline Defaultable(const T& v, bool def = false) : value(v), is_default(def) {}
  
  /// Assigning a value takes this object out of the default state
  inline void assign(const T& new_value) {
    value      = new_value;
    is_default = false;
  }
  /// Assigning a value keep this object in the default state
  inline void assignDefault(const T& new_value) {
    assert(is_default);
    value      = new_value;
  }
  /// Assigning a value, don't change the defaultness
  inline void assignDontChangeDefault(const T& new_value) {
    value = new_value;
  }
  
  /// Get access to the value
  inline operator const T& () const { return value; }
  inline const T& operator () () const { return value; }
  /// Get access to the value, for changing it
  inline       T& mutate      ()       {
    is_default = false;
    return value;
  }
  /// Get access to the value, for changing it, don't change the defaultness
  inline T& mutateDontChangeDefault() { return value; }
  
  /// Is this value in the default state?
  inline bool isDefault() const { return is_default; }
  /// Set the defaultness to d
  inline void makeDefault(bool d = true) { is_default = d; }
  
  /// Compare the values, ignore defaultness
  /** used by scriptable to check for changes */
  inline bool operator != (const Defaultable& that) const { return value != that.value; }
  
private:
  /// The value
  T value;
  /// Is this value in the default state?
  bool is_default;
  
  friend class Reader;
  friend class Writer;
};

// we need some custom io, because the behaviour is different for each of Reader/Writer/GetMember

template <typename T>
void Reader::handle(Defaultable<T>& def) {
  def.is_default = false;
  handle(def.value);
}
template <typename T>
void Writer::handle(const Defaultable<T>& def) {
  if (!def.isDefault()) {
    handle(def());
  }
}
template <typename T>
void GetDefaultMember::handle(const Defaultable<T>& def) {
  handle(def());
}