// m_move.c -- monster movement

#include "g_local.h"

#define	STEPSIZE	18

/*
M_CheckBottom

Returns false if any part of the bottom of the entity is off an edge that
is not a staircase.

*/
int c_yes, c_no;

qboolean M_CheckBottom(edict_t *ent){
	vec3_t	mins, maxs, start, stop;
	trace_t	trace;
	int		x, y;
	float	mid, bottom;
	
	VectorAdd(ent->s.origin, ent->mins, mins);
	VectorAdd(ent->s.origin, ent->maxs, maxs);
	
// if all of the points under the corners are solid world, don't bother
// with the tougher checks
// the corners must be within 16 of the midpoint
	start[2] = mins[2] - 1;
	for	(x = 0 ; x <= 1 ; x++)
		for	(y = 0 ; y <= 1 ; y++){
			start[0] = x ? maxs[0] : mins[0];
			start[1] = y ? maxs[1] : mins[1];
			if(gi.pointcontents(start) != CONTENTS_SOLID)
				goto realcheck;
		}
		
	c_yes++;
	return true;		// we got out easy
	
realcheck:
	c_no++;
//
// check it for real...
//
	start[2] = mins[2];
	
// the midpoint must be within 16 of the bottom
	start[0] = stop[0] = (mins[0] + maxs[0]) * 0.5;
	start[1] = stop[1] = (mins[1] + maxs[1]) * 0.5;
	stop[2] = start[2] - 2 * STEPSIZE;
	trace = gi.trace(start, vec3_origin, vec3_origin, stop, ent, MASK_MONSTERSOLID);
	
	if(trace.fraction == 1.0)
		return false;
	mid = bottom = trace.endpos[2];
	
// the corners must be within 16 of the midpoint
	for	(x = 0 ; x <= 1 ; x++)
		for	(y = 0 ; y <= 1 ; y++){
			start[0] = stop[0] = x ? maxs[0] : mins[0];
			start[1] = stop[1] = y ? maxs[1] : mins[1];
			
			trace = gi.trace(start, vec3_origin, vec3_origin, stop, ent, MASK_MONSTERSOLID);
			
			if(trace.fraction != 1.0 && trace.endpos[2] > bottom)
				bottom = trace.endpos[2];
			if(trace.fraction == 1.0 || mid - trace.endpos[2] > STEPSIZE)
				return false;
		}
		
	c_yes++;
	return true;
}


/*
SV_movestep

Called by monster program code.
The move will be adjusted for slopes and stairs, but if the move isn't
possible, no move is done, false is returned, and
pr_global_struct->trace_normal is set to the normal of the blocking wall
*/
//FIXME since we need to test end position contents here, can we avoid doing
//it again later in catagorize position?
qboolean SV_movestep(edict_t *ent, vec3_t move, qboolean relink){
	float		dz;
	vec3_t		oldorg, neworg, end;
	trace_t		trace;
	int			i;
	float		stepsize;
	vec3_t		test;
	int			contents;
	
// try the move
	VectorCopy(ent->s.origin, oldorg);
	VectorAdd(ent->s.origin, move, neworg);
	
// flying monsters don't step up
	if(ent->flags & (FL_SWIM | FL_FLY)){
		// try one move with vertical motion, then one without
		for(i = 0 ; i < 2 ; i++){
			VectorAdd(ent->s.origin, move, neworg);
			if(i == 0 && ent->enemy){
				if(!ent->goalentity)
					ent->goalentity = ent->enemy;
				dz = ent->s.origin[2] - ent->goalentity->s.origin[2];
				if(ent->goalentity->client){
					if(dz > 40)
						neworg[2] -= 8;
					if(!((ent->flags & FL_SWIM) && (ent->waterlevel < 2)))
						if(dz < 30)
							neworg[2] += 8;
				} else {
					if(dz > 8)
						neworg[2] -= 8;
					else if(dz > 0)
						neworg[2] -= dz;
					else if(dz < -8)
						neworg[2] += 8;
					else
						neworg[2] += dz;
				}
			}
			trace = gi.trace(ent->s.origin, ent->mins, ent->maxs, neworg, ent, MASK_MONSTERSOLID);
			
			// fly monsters don't enter water voluntarily
			if(ent->flags & FL_FLY){
				if(!ent->waterlevel){
					test[0] = trace.endpos[0];
					test[1] = trace.endpos[1];
					test[2] = trace.endpos[2] + ent->mins[2] + 1;
					contents = gi.pointcontents(test);
					if(contents & MASK_WATER)
						return false;
				}
			}
			
			// swim monsters don't exit water voluntarily
			if(ent->flags & FL_SWIM){
				if(ent->waterlevel < 2){
					test[0] = trace.endpos[0];
					test[1] = trace.endpos[1];
					test[2] = trace.endpos[2] + ent->mins[2] + 1;
					contents = gi.pointcontents(test);
					if(!(contents & MASK_WATER))
						return false;
				}
			}
			
			if(trace.fraction == 1){
				VectorCopy(trace.endpos, ent->s.origin);
				if(relink){
					gi.linkentity(ent);
					G_TouchTriggers(ent);
				}
				return true;
			}
			
			if(!ent->enemy)
				break;
		}
		
		return false;
	}
	
// push down from a step height above the wished position
	if(!(ent->monsterinfo.aiflags & AI_NOSTEP))
		stepsize = STEPSIZE;
	else
		stepsize = 1;
		
	neworg[2] += stepsize;
	VectorCopy(neworg, end);
	end[2] -= stepsize * 2;
	
	trace = gi.trace(neworg, ent->mins, ent->maxs, end, ent, MASK_MONSTERSOLID);
	
	if(trace.allsolid)
		return false;
		
	if(trace.startsolid){
		neworg[2] -= stepsize;
		trace = gi.trace(neworg, ent->mins, ent->maxs, end, ent, MASK_MONSTERSOLID);
		if(trace.allsolid || trace.startsolid)
			return false;
	}
	
	
	// don't go in to water
	if(ent->waterlevel == 0){
		test[0] = trace.endpos[0];
		test[1] = trace.endpos[1];
		test[2] = trace.endpos[2] + ent->mins[2] + 1;
		contents = gi.pointcontents(test);
		
		if(contents & MASK_WATER)
			return false;
	}
	
	if(trace.fraction == 1){
		// if monster had the ground pulled out, go ahead and fall
		if(ent->flags & FL_PARTIALGROUND){
			VectorAdd(ent->s.origin, move, ent->s.origin);
			if(relink){
				gi.linkentity(ent);
				G_TouchTriggers(ent);
			}
			ent->groundentity = NULL;
			return true;
		}
		
		return false;		// walked off an edge
	}
	
// check point traces down for dangling corners
	VectorCopy(trace.endpos, ent->s.origin);
	
	if(!M_CheckBottom(ent)){
		if(ent->flags & FL_PARTIALGROUND){	// entity had floor mostly pulled out from underneath it
			// and is trying to correct
			if(relink){
				gi.linkentity(ent);
				G_TouchTriggers(ent);
			}
			return true;
		}
		VectorCopy(oldorg, ent->s.origin);
		return false;
	}
	
	if(ent->flags & FL_PARTIALGROUND){
		ent->flags &= ~FL_PARTIALGROUND;
	}
	ent->groundentity = trace.ent;
	ent->groundentity_linkcount = trace.ent->linkcount;
	
// the move is ok
	if(relink){
		gi.linkentity(ent);
		G_TouchTriggers(ent);
	}
	return true;
}



/*
M_ChangeYaw

*/
void M_ChangeYaw(edict_t *ent){
	float	ideal;
	float	current;
	float	move;
	float	speed;
	
	current = anglemod(ent->s.angles[YAW]);
	ideal = ent->ideal_yaw;
	
	if(current == ideal)
		return;
		
	move = ideal - current;
	speed = ent->yaw_speed;
	if(ideal > current){
		if(move >= 180)
			move = move - 360;
	} else {
		if(move <= -180)
			move = move + 360;
	}
	if(move > 0){
		if(move > speed)
			move = speed;
	} else {
		if(move < -speed)
			move = -speed;
	}
	
	ent->s.angles[YAW] = anglemod(current + move);
}


/*
SV_StepDirection

Turns to the movement direction, and walks the current distance if
facing it.

*/
qboolean SV_StepDirection(edict_t *ent, float yaw, float dist){
	vec3_t		move, oldorigin;
	float		delta;
	
	ent->ideal_yaw = yaw;
	M_ChangeYaw(ent);
	
	yaw = yaw * M_PI * 2 / 360;
	move[0] = cos(yaw) * dist;
	move[1] = sin(yaw) * dist;
	move[2] = 0;
	
	VectorCopy(ent->s.origin, oldorigin);
	if(SV_movestep(ent, move, false)){
		delta = ent->s.angles[YAW] - ent->ideal_yaw;
		if(delta > 45 && delta < 315){		// not turned far enough, so don't take the step
			VectorCopy(oldorigin, ent->s.origin);
		}
		gi.linkentity(ent);
		G_TouchTriggers(ent);
		return true;
	}
	gi.linkentity(ent);
	G_TouchTriggers(ent);
	return false;
}

/*
SV_FixCheckBottom

*/
void SV_FixCheckBottom(edict_t *ent){
	ent->flags |= FL_PARTIALGROUND;
}



/*
SV_NewChaseDir

*/
#define	DI_NODIR	-1
void SV_NewChaseDir(edict_t *actor, edict_t *enemy, float dist){
	float	deltax, deltay;
	float	d[3];
	float	tdir, olddir, turnaround;
	
	//FIXME: how did we get here with no enemy
	if(!enemy)
		return;
		
	olddir = anglemod((int)(actor->ideal_yaw / 45) * 45);
	turnaround = anglemod(olddir - 180);
	
	deltax = enemy->s.origin[0] - actor->s.origin[0];
	deltay = enemy->s.origin[1] - actor->s.origin[1];
	if(deltax > 10)
		d[1] = 0;
	else if(deltax < -10)
		d[1] = 180;
	else
		d[1] = DI_NODIR;
	if(deltay < -10)
		d[2] = 270;
	else if(deltay > 10)
		d[2] = 90;
	else
		d[2] = DI_NODIR;
		
// try direct route
	if(d[1] != DI_NODIR && d[2] != DI_NODIR){
		if(d[1] == 0)
			tdir = d[2] == 90 ? 45 : 315;
		else
			tdir = d[2] == 90 ? 135 : 215;
			
		if(tdir != turnaround && SV_StepDirection(actor, tdir, dist))
			return;
	}
	
// try other directions
	if(((rand()&3) & 1) ||  abs(deltay) > abs(deltax)){
		tdir = d[1];
		d[1] = d[2];
		d[2] = tdir;
	}
	
	if(d[1] != DI_NODIR && d[1] != turnaround
	        && SV_StepDirection(actor, d[1], dist))
		return;
		
	if(d[2] != DI_NODIR && d[2] != turnaround
	        && SV_StepDirection(actor, d[2], dist))
		return;
		
	/* there is no direct path to the player, so pick another direction */
	
	if(olddir != DI_NODIR && SV_StepDirection(actor, olddir, dist))
		return;
		
	if(rand()&1) 	/*randomly determine direction of search*/
	{
		for(tdir = 0 ; tdir <= 315 ; tdir += 45)
			if(tdir != turnaround && SV_StepDirection(actor, tdir, dist))
				return;
	} else {
		for(tdir = 315 ; tdir >= 0 ; tdir -= 45)
			if(tdir != turnaround && SV_StepDirection(actor, tdir, dist))
				return;
	}
	
	if(turnaround != DI_NODIR && SV_StepDirection(actor, turnaround, dist))
		return;
		
	actor->ideal_yaw = olddir;		// can't move
	
// if a bridge was pulled out from underneath a monster, it may not have
// a valid standing position at all

	if(!M_CheckBottom(actor))
		SV_FixCheckBottom(actor);
}

/*
SV_CloseEnough

*/
qboolean SV_CloseEnough(edict_t *ent, edict_t *goal, float dist){
	int		i;
	
	for(i = 0 ; i < 3 ; i++){
		if(goal->absmin[i] > ent->absmax[i] + dist)
			return false;
		if(goal->absmax[i] < ent->absmin[i] - dist)
			return false;
	}
	return true;
}


/*
M_MoveToGoal
*/
void M_MoveToGoal(edict_t *ent, float dist){
	edict_t		*goal;
	
	goal = ent->goalentity;
	
	if(!ent->groundentity && !(ent->flags & (FL_FLY | FL_SWIM)))
		return;
		
// if the next step hits the enemy, return immediately
	if(ent->enemy &&  SV_CloseEnough(ent, ent->enemy, dist))
		return;
		
// bump around...
	if((rand()&3) == 1 || !SV_StepDirection(ent, ent->ideal_yaw, dist)){
		if(ent->inuse)
			SV_NewChaseDir(ent, goal, dist);
	}
}


/*
M_walkmove
*/
qboolean M_walkmove(edict_t *ent, float yaw, float dist){
	vec3_t	move;
	
	if(!ent->groundentity && !(ent->flags & (FL_FLY | FL_SWIM)))
		return false;
		
	yaw = yaw * M_PI * 2 / 360;
	
	move[0] = cos(yaw) * dist;
	move[1] = sin(yaw) * dist;
	move[2] = 0;
	
	return SV_movestep(ent, move, true);
}