// FileEvent.h

#ifndef hes_FileEvent_H
#define hes_FileEvent_H

// David Adams
// March 2002
//
// Mixin defining the event ID part of the hes::File interface.
// This maintains an event ID list and a current event ID.

#include "hesfile/File.h"
#include "hesbase/EventId.h"

namespace hes {

class FileEvent : public virtual File {

private:  // data

  // Event ID list.
  EventIdList m_evids;

  // min and max event ID's
  EventId m_min_evid;
  EventId m_max_evid;

  // Current event iterator.
  // end means undefined.
  EventIdList::const_iterator m_ievid;

private:  // functions

  // Change the event ID.
  // All requests to change the current event ID come through here.
  // The new ID is returned.
  // Virtual functions end_event() and begin_event() are called so that
  // subclasses can clean up and initialize, respectively.
  EventId set_event_iter(EventIdList::const_iterator ievid);

public:  // New interface

  // Notification that a new current event has been set.
  virtual void begin_event() =0;

  // Notification that the current event is bout to end.
  virtual void end_event() =0;

public:  // Functions

  // Constructor.
  FileEvent();

  // Add an event ID.
  // Current event does not change.
  // Returns the total number of event ID's.
  // Returns 0 for error.
  int add_event_id(EventId evid);

public:  // Implement File interface.

  // Return the number of events.
  int event_count() const;

  // Return the event range.
  EventId min_event() const;
  EventId max_event() const;

  // Return the list of event ID's included in this file.
  // The file includes one placement catgory of each of the above types
  // for each event in the file.
  const EventIdList& event_ids() const;

  // Return the current event ID.
  EventId event() const;

  // Set the current event.
  // No change if the event is not present.
  // Returns the current event.
  EventId set_event(EventId evid);
  
  // Set the current event to the first event.
  // The ID of that event is returned.
  EventId first_event();
  
  // Set the current event to the last event.
  // The ID of that event is returned.
  EventId last_event();
  
  // Go to the next event.
  // The ID of that event is returned.
  // An invalid ID should be returned when the list is exhausted.
  EventId next_event();

};
  
}  // end namespace

#endif