/*
 *	DNN - Data News Network
 *
 *	by Stephane Chatty
 *
 *	Copyright 1993-1995
 *	Centre d'Etudes de la Navigation Aerienne (CENA)
 *
 *	Event triggers.
 *
 *	$Id$
 *	$CurLog$
 */

#include "Trigger.h"
#include "Reaction.h"
#include "Criterion.h"

/*?class IvlTrigger
\typ{IvlTrigger}s are the core of event detection and emission. The presence of a trigger
(generally in a sensor) determines whether a certain situation, or the reception
of an event from the underlying window system, should provoke the emission of an event.
Each trigger holds a list of reactions (of type \typ{IvlBaseReaction}). These reactions will
receive all the events whose creation and emission was caused by the presence of
the trigger.
?*/

/*?
Create a trigger with an empty list of associated reaction.
?*/
IvlTrigger :: IvlTrigger ()
: FirstSubscribers (),
  LastSubscribers (),
  Subscribers (),
  Grabs (),
  Criteria ()
{
}

/*?nodoc?*/
IvlTrigger :: ~IvlTrigger ()
{
	/* Force reactions to unsubscribe.
	    We should take care of conditions when destructor is called
	    during iteration */

	IvlListIterOf <IvlBaseReaction> ri  = FirstSubscribers;
	while (++ri)
		(*ri)->Forget (*this);
	ri = Subscribers;
	while (++ri)
		(*ri)->Forget (*this);
	ri = LastSubscribers;
	while (++ri)
		(*ri)->Forget (*this);
	ri = Grabs;
	while (++ri)
		(*ri)->Forget (*this);
}

/*?nextdoc?*/
void
IvlTrigger :: Subscribe (IvlBaseReaction& a, REL_PRIORITY p)
{
	switch (p) {
	case isFirstPriority:
		FirstSubscribers.Append (&a);
		break;
	case isNormalPriority:
		Subscribers.Append (&a);
		break;
	case isLastPriority:
		LastSubscribers.Prepend (&a);
		break;
	}
}

/*?
Add (resp. Remove) a reaction to (resp. from) the list of reactions that should receive
events caused by this trigger.
?*/
void
IvlTrigger :: Unsubscribe (IvlBaseReaction& a)
{
	FirstSubscribers.Remove (&a);
	Subscribers.Remove (&a);
	LastSubscribers.Remove (&a);
	Grabs.Remove (&a);
}

/*?nextdoc?*/
void
IvlTrigger :: Grab (IvlBaseReaction& a)
{
	Grabs.Prepend (&a);
}

/*?
Add (resp. Remove) a reaction onto (resp. from) the stack of reactions that preempt
events caused by this trigger.
?*/
void
IvlTrigger :: Release (IvlBaseReaction& a)
{
	Grabs.Remove (&a);
}

#if 0
void
IvlTrigger :: Circulate (IvlBaseReaction& r, REL_POS pos, IvlBaseReaction* ref)
{

	if (Subscribers.Remove (&r)) {
		/* find the predecessor of ref */
		IvlListIterOf <IvlBaseReaction> lc = Subscribers;
		while (++lc && (*lc != ref))
			;
		/* NOW, lc is on ref, or at the end if ref == 0 */
		if (pos == isBefore)
			Subscribers.InsertBefore (lc, &r);
		else
			Subscribers.InsertAfter (lc, &r);
	}

}
#endif

/*?
Have a trigger dispatch the event \var{ev} to its associated reactions.
?*/
void
IvlTrigger :: Dispatch (IvlEvent& ev)
{
	IvlBaseReaction* r = Grabs.First ();
	if (r) {
		r->Manage (ev);
	} else {
		/* calls to Manage may result in changes in Subscribers; let's make a safe copy */
		IvlListOf <IvlBaseReaction> first_subscribers = FirstSubscribers;
		IvlListOf <IvlBaseReaction> subscribers = Subscribers;
		IvlListOf <IvlBaseReaction> last_subscribers = LastSubscribers;

		IvlListIterOf <IvlBaseReaction> s = first_subscribers;
		while (++s)
#ifdef CRITERIA_IN_REACTIONS
			if ((*s)->Check (ev))
#endif
			(*s)->Manage (ev);

		s = subscribers;
		while (++s)
#ifdef CRITERIA_IN_REACTIONS
			if ((*s)->Check (ev))
#endif
			(*s)->Manage (ev);

		s = last_subscribers;
		while (++s)
#ifdef CRITERIA_IN_REACTIONS
			if ((*s)->Check (ev))
#endif
			(*s)->Manage (ev);
	}
}

bool
IvlTrigger :: Check (IvlEvent& ev)
{
	IvlListIterOf <IvlBaseCriterion> c = Criteria;
	while (++c)
		if (!(*c)->Test (ev))
			return false;

#ifdef CRITERIA_IN_REACTIONS
	IvlListIterOf <IvlBaseReaction> ri  = FirstSubscribers;
	while (++ri)
		if ((*ri)->Check (ev))
			return true;
	ri = Subscribers;
	while (++ri)
		if ((*ri)->Check (ev))
			return true;
	ri = LastSubscribers;
	while (++ri)
		if ((*ri)->Check (ev))
			return true;
	return false;
#else
	return true;
#endif
}