#ifndef AGDDATTRIBUTEHH
#define AGDDATTRIBUTEHH

#include <string>
#include "ExpatInterface/Element.h"

namespace agdd {

  class Attribute {
  public:
    typedef enum { required, implied, hasDefault } Status;
  private:
    string _name;
    bool   _set;
    Status _status;
    string _default;
    string _value;
  public:
    explicit Attribute(const string & name, 
		       const Status status) : 
      _name(name), _set(false), _status(status), _default() {
      assert(status != hasDefault);
      assert(name!=static_cast<std::string>(""));
    };
    explicit Attribute(const string & name, 
		       const Status status, 
		       const string & defaultt) :
      _name(name), _set(false), _status(status), _default(defaultt) {
      // Check not silly
      assert(status==hasDefault);
      assert(name!=static_cast<std::string>(""));
    };
    explicit Attribute(const string & name, 
		       const string & defaultt) :
      _name(name), _set(false), _status(hasDefault), _default(defaultt) {
      assert(name!=static_cast<std::string>(""));
    };
      //Attribute & 
    void setValue(const string & value) {
      _value = value;
      _set   = true;
      // return *this;
    };
    const string getSetValue() const {
      assert(_set);
      return _value;
    };
    const string getSetOrDefaultValue() const {
      if (_set) {
	return _value;
      } else {
	if (_status!=hasDefault) {
	  cerr << "ERROR: The method agddAttribute::getSetOrDefaultValue" << endl
	       << "is being used from an attribute called <"<<_name<<"> which was never set" << endl
	       << "and which lacks a default.  This is illegal." << endl;
	}
	assert(_status==hasDefault);
	return _default;
      }
    };
    const string getDefaultValue() const {
      assert(_status==hasDefault);
      return _default;
    };
    const Status getStatus() const {
      return _status;
    };
  private:
    void addAttributeTo(xml::Element & elt) {
      if (_set) {
	elt.addAttribute(_name, _value);
	return;
      }
      // Was not set. Therefore
      
      if (_status==required) {
	cerr << "Error: An attribute called <" 
	     << _name
	     << "> is required, but has not been set."
	     << endl;
      }

      assert(_status!=required);
      if (_status==implied) {
	// Do nothing.
	return;
      }
      // Only one possibility left
      assert(_status==hasDefault);
      elt.addAttribute(_name, _default);
      return;
    };
  public:
    void addAttributeTo(xml::Element * elt) {
      assert(elt);
      addAttributeTo(*elt);
    };
  };

} // end of namespace

#endif