#include "g_local.h"


/*

PLAYER TRAIL


This is a circular list containing the a list of points of where
the player has been recently.  It is used by monsters for pursuit.

.origin		the spot
.owner		forward link
.aiment		backward link
*/


#define	TRAIL_LENGTH	8

edict_t		*trail[TRAIL_LENGTH];
int			trail_head;
qboolean	trail_active = false;

#define NEXT(n)		(((n) + 1) & (TRAIL_LENGTH - 1))
#define PREV(n)		(((n) - 1) & (TRAIL_LENGTH - 1))


void PlayerTrail_Init(void){
	int		n;
	
	if(deathmatch->value /* FIXME || coop */)
		return;
		
	for(n = 0; n < TRAIL_LENGTH; n++){
		trail[n] = G_Spawn();
		trail[n]->classname = "player_trail";
	}
	
	trail_head = 0;
	trail_active = true;
}


void PlayerTrail_Add(vec3_t spot){
	vec3_t	temp;
	
	if(!trail_active)
		return;
		
	VectorCopy(spot, trail[trail_head]->s.origin);
	
	trail[trail_head]->timestamp = level.time;
	
	VectorSubtract(spot, trail[PREV(trail_head)]->s.origin, temp);
	trail[trail_head]->s.angles[1] = vectoyaw(temp);
	
	trail_head = NEXT(trail_head);
}


void PlayerTrail_New(vec3_t spot){
	if(!trail_active)
		return;
		
	PlayerTrail_Init();
	PlayerTrail_Add(spot);
}


edict_t *PlayerTrail_PickFirst(edict_t *self){
	int		marker;
	int		n;
	
	if(!trail_active)
		return NULL;
		
	for(marker = trail_head, n = TRAIL_LENGTH; n; n--){
		if(trail[marker]->timestamp <= self->monsterinfo.trail_time)
			marker = NEXT(marker);
		else
			break;
	}
	
	if(visible(self, trail[marker])){
		return trail[marker];
	}
	
	if(visible(self, trail[PREV(marker)])){
		return trail[PREV(marker)];
	}
	
	return trail[marker];
}

edict_t *PlayerTrail_PickNext(edict_t *self){
	int		marker;
	int		n;
	
	if(!trail_active)
		return NULL;
		
	for(marker = trail_head, n = TRAIL_LENGTH; n; n--){
		if(trail[marker]->timestamp <= self->monsterinfo.trail_time)
			marker = NEXT(marker);
		else
			break;
	}
	
	return trail[marker];
}

edict_t *PlayerTrail_LastSpot(void){
	return trail[PREV(trail_head)];
}