#ifndef __EVENT_QUEUE_H__
#define __EVENT_QUEUE_H__

#include <vector>

#include "bluesim_types.h"
#include "priority.h"

// Forward declaration of the recursive type tEvent
typedef struct tEvent tEvent;

// A tEventData is a union type used to pass data to an event
// handler function.
typedef union
{
  void*        ptr;
  bool         flag;
  tClock       clk;
  unsigned int value;
} tEventData;

// A tEventFn is the type of functions which can be scheduled for
// execution at a given time.  The tEventData argument is a data
// value associated with the event.  The return value is
// an interval at which to reschedule the event, or 0 to not
// reschedule.
typedef tTime (*tEventFn)(tSimStateHdl, tEvent&);

// A tEvent combines a time and priority with a callback function and
// a void* to some data which is supplied to the callback function.
struct tEvent
{
  tTime      at;
  tPriority  priority;
  tEventFn   fn;
  tEventData data;
};

// Type of predicate function used for searching and filtering
// an event queue.
typedef bool (*tEventPredicate)(tSimStateHdl, const tEvent&);

// An EventQueue provides a simple priority queue interface
class EventQueue
{
 private:
  std::vector<tEvent> events;
  unsigned int        count;

  bool                in_event;
  tEvent              executing_event;
  bool                removed_self;

  // queue search state
  mutable tEventPredicate last_find_pred;
  mutable unsigned int curr_find_idx;

 public:
  EventQueue();
  ~EventQueue();

  // schedule an event
  void schedule(const tEvent& e);

  // execute events in sequence
  void execute(tSimStateHdl simHdl);

  // get the number of events in the queue
  unsigned int size() const;

  // find an event satisfying the predicate in the queue
  // Note: giving a NULL predicate repeats the previous
  // search to find the next match, if any.  Matches are
  // *NOT* guaranteed to be returned in order.
  const tEvent* find(tSimStateHdl simHdl, tEventPredicate pred) const;

  // remove all events satisfying a predicate
  void remove(tSimStateHdl simHdl, tEventPredicate pred);

  // remove all events
  void clear();

  // debugging utility function
  void print() const;

 private: // heap maintenance functions
  bool isValid();
  void bubble_up(unsigned int idx);
  void bubble_down(unsigned int idx);
};

#endif /* __EVENT_QUEUE_H__ */