/*
	Copyright (C) 1996-1997  Id Software, Inc.

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

	See file, 'COPYING', for details.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

static __attribute__ ((used)) const char rcsid[] =
	"$Id$";

#ifdef HAVE_STRING_H
# include <string.h>
#endif

#include "QF/sys.h"

#include "compat.h"

#include "brush.h"
#include "bsp5.h"
#include "options.h"
#include "winding.h"
#include "tjunc.h"

typedef struct wvert_s {
	vec_t       t;
	struct wvert_s *prev, *next;
} wvert_t;

typedef struct wedge_s {
	struct wedge_s *next;
	vec3_t      dir;
	vec3_t      origin;
	wvert_t     head;
} wedge_t;

int         numwedges, numwverts;
int         tjuncs;
int         tjuncfaces;
int         degenerdges;

#define	MAXWVERTS	0x20000
#define	MAXWEDGES	0x10000

wvert_t     wverts[MAXWVERTS];
wedge_t     wedges[MAXWEDGES];

#define	NUM_HASH	1024

wedge_t    *wedge_hash[NUM_HASH];

static vec3_t hash_min, hash_scale;

/**	Initialize the edge hash table.

	\param mins		The minimum of the bounding box in which the edges reside.
	\param maxs		The maximum of the bounding box in which the edges reside.
*/
static void
InitHash (vec3_t mins, vec3_t maxs)
{
	int         newsize[2];
	vec3_t      size;
	vec_t       volume;
	vec_t       scale;

	VectorCopy (mins, hash_min);
	VectorSubtract (maxs, mins, size);
	memset (wedge_hash, 0, sizeof (wedge_hash));

	volume = size[0] * size[1];

	scale = sqrt (volume / NUM_HASH);

	newsize[0] = size[0] / scale;
	newsize[1] = size[1] / scale;

	hash_scale[0] = newsize[0] / size[0];
	hash_scale[1] = newsize[1] / size[1];
	hash_scale[2] = newsize[1];
}

/**	Calulate the hash value of a vector.

	\param vec		The vector for which to calculate the hash value.
	\return			The hash value of the vector.
*/
static unsigned
HashVec (vec3_t vec)
{
	unsigned    h;

	h = hash_scale[0] * (vec[0] - hash_min[0]) * hash_scale[2]
		+ hash_scale[1] * (vec[1] - hash_min[1]);
	if (h >= NUM_HASH)
		return NUM_HASH - 1;
	return h;
}

/**	Make the vector canonical.

	A canonical vector is a unit vector with the first non-zero axis
	positive.

	\param vec		The vector to make canonical.
	\return			false is the vector is (0, 0, 0), otherwise true.
*/
static qboolean
CanonicalVector (vec3_t vec)
{
	vec_t       len = _VectorNormalize (vec);

	if (len < EQUAL_EPSILON)
		return false;

	if (vec[0] > EQUAL_EPSILON) {
		return true;
	} else if (vec[0] < -EQUAL_EPSILON) {
		VectorNegate (vec, vec);
		return true;
	} else {
		vec[0] = 0;
	}

	if (vec[1] > EQUAL_EPSILON) {
		return true;
	} else if (vec[1] < -EQUAL_EPSILON) {
		VectorNegate (vec, vec);
		return true;
	} else {
		vec[1] = 0;
	}

	if (vec[2] > EQUAL_EPSILON) {
		return true;
	} else if (vec[2] < -EQUAL_EPSILON) {
		VectorNegate (vec, vec);
		return true;
	} else {
		vec[2] = 0;
	}
	return false;
}

/**	Find a wedge for the two points.

	A wedge is an infinitely long line passing through the two points with
	an "origin" at t=0.

	\param p1		The first point.
	\param p2		The second point.
	\param t1		The "time" of one of the points.
	\param t2		The "time" of the other point.
	\return			Pointer to the wedge, or NULL for a degenerate edge
					(zero length).

	\note t2 will always be greater than t1, so there's no guarantee which
	point is represented by t1 and t2.
*/
static wedge_t *
FindEdge (vec3_t p1, vec3_t p2, vec_t *t1, vec_t *t2)
{
	int         h;
	vec3_t      dir, origin;
	vec_t       temp;
	wedge_t    *w;

	VectorSubtract (p2, p1, dir);

	if (!CanonicalVector (dir)) {
		degenerdges++;
		return 0;
	}

	*t1 = DotProduct (p1, dir);
	*t2 = DotProduct (p2, dir);

	VectorMultSub (p1, *t1, dir, origin);

	if (*t1 > *t2) {
		// swap t1 and t2
		temp = *t1;
		*t1 = *t2;
		*t2 = temp;
	}

	h = HashVec (origin);

	for (w = wedge_hash[h]; w; w = w->next) {
		if (!_VectorCompare (w->origin, origin))
			continue;
		if (!_VectorCompare (w->dir, dir))
			continue;
		return w;
	}

	// create a new wedge
	if (numwedges == MAXWEDGES)
		Sys_Error ("FindEdge: numwedges == MAXWEDGES");
	w = &wedges[numwedges];
	numwedges++;

	w->next = wedge_hash[h];
	wedge_hash[h] = w;

	VectorCopy (origin, w->origin);
	VectorCopy (dir, w->dir);
	w->head.next = w->head.prev = &w->head;
	w->head.t = 99999;
	return w;
}

#define	T_EPSILON	0.01

/**	Add a wvert to the wedge.

	A wvert is a vertex on the wedge and is specified by the time along the
	wedge from the wedge's origin.

	If a wvert with the same time already exists, a new one will not be added.

	\param w		The wedge to which the wvert will be added.
	\param t		The "time" of the wvert.
*/
static void
AddVert (wedge_t *w, vec_t t)
{
	wvert_t    *v, *newv;

	v = w->head.next;
	do {
		if (fabs (v->t - t) < T_EPSILON)
			return;
		if (v->t > t)
			break;
		v = v->next;
	} while (1);

	// insert a new wvert before v
	if (numwverts == MAXWVERTS)
		Sys_Error ("AddVert: numwverts == MAXWVERTS");

	newv = &wverts[numwverts];
	numwverts++;

	newv->t = t;
	newv->next = v;
	newv->prev = v->prev;
	v->prev->next = newv;
	v->prev = newv;
}

/**	Add a faces edge to the wedge system.

	\param p1		The first point of the face's edge.
	\param p2		The second point of the face's edge.
*/
static void
AddEdge (vec3_t p1, vec3_t p2)
{
	wedge_t    *w;
	vec_t       t1, t2;

	if ((w = FindEdge (p1, p2, &t1, &t2))) {
		AddVert (w, t1);
		AddVert (w, t2);
	}
}

/**	Add the edges from the face.

	\param f		The face from which to add the faces.
*/
static void
AddFaceEdges (face_t *f)
{
	int         i, j;

	for (i = 0; i < f->points->numpoints; i++) {
		j = (i + 1) % f->points->numpoints;
		AddEdge (f->points->points[i], f->points->points[j]);
	}
}

face_t     *newlist;

/**	Check and fix the edges of the face.

	If any vertices from other faces lie on an edge of the face between the
	edge's end points, add matching vertices along that edge.

	\param f		The face of which the edges will be checked.
*/
static void
FixFaceEdges (face_t *f)
{
	int         i, j, k;
	vec_t       t1, t2;
	wedge_t    *w;
	winding_t  *fp = f->points;
	wvert_t    *v;

  restart:
	for (i = 0; i < fp->numpoints; i++) {
		j = (i + 1) % fp->numpoints;

		if (!(w = FindEdge (fp->points[i], fp->points[j], &t1, &t2)))
			continue;

		for (v = w->head.next; v->t < t1 + T_EPSILON; v = v->next) {
		}

		if (v->t < t2 - T_EPSILON) {
			tjuncs++;
			// insert a new vertex here
			fp = realloc (fp, field_offset (winding_t,
											points[fp->numpoints + 1]));
			for (k = fp->numpoints; k > j; k--) {
				VectorCopy (fp->points[k - 1], fp->points[k]);
			}
			VectorMultAdd (w->origin, v->t, w->dir, fp->points[j]);
			fp->numpoints++;
			goto restart;
		}
	}
	f->points = fp;

	f->next = newlist;
	newlist = f;
}

static void
tjunc_find_r (node_t *node)
{
	face_t     *f;

	if (node->planenum == PLANENUM_LEAF)
		return;

	for (f = node->faces; f; f = f->next)
		if (f->texturenum >= 0)
			AddFaceEdges (f);

	tjunc_find_r (node->children[0]);
	tjunc_find_r (node->children[1]);
}

/**	Check and fix the edges from the faces in the bsp tree.

	\param node		The current node in the bsp tree.
*/
static void
tjunc_fix_r (node_t *node)
{
	face_t     *next, *f;

	if (node->planenum == PLANENUM_LEAF)
		return;

	newlist = NULL;

	for (f = node->faces; f; f = next) {
		next = f->next;
		if (f->texturenum < 0)
			continue;
		FixFaceEdges (f);
	}

	node->faces = newlist;

	tjunc_fix_r (node->children[0]);
	tjunc_fix_r (node->children[1]);
}

void
tjunc (node_t *headnode)
{
	int         i;
	vec3_t      maxs, mins;

	qprintf ("---- tjunc ----\n");

	if (options.notjunc)
		return;

	// origin points won't allways be inside the map, so extend the hash area
	for (i = 0; i < 3; i++) {
		if (fabs (brushset->maxs[i]) > fabs (brushset->mins[i]))
			maxs[i] = fabs (brushset->maxs[i]);
		else
			maxs[i] = fabs (brushset->mins[i]);
	}
	VectorNegate (maxs, mins);

	InitHash (mins, maxs);

	numwedges = numwverts = 0;

	// identify all points on common edges
	tjunc_find_r (headnode);

	qprintf ("%i world edges  %i edge points\n", numwedges, numwverts);

	// add extra vertexes on edges where needed
	tjuncs = tjuncfaces = 0;
	degenerdges = 0;

	tjunc_fix_r (headnode);

	qprintf ("%i degenerate edges\n", degenerdges);
	qprintf ("%i edges added by tjunctions\n", tjuncs);
	qprintf ("%i faces added by tjunctions\n", tjuncfaces);
}