/*
	flow.c

	PVS PHS generator tool

	Copyright (C) 1996-1997  Id Software, Inc.
	Copyright (C) 2002 Colin Thompson

	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:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA	02111-1307, USA

*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <getopt.h>
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#ifdef HAVE_IO_H
# include <io.h>
#endif
#ifdef HAVE_STRING_H
# include <string.h>
#endif
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif
#include <getopt.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>

#include "QF/alloc.h"
#include "QF/bspfile.h"
#include "QF/cmd.h"
#include "QF/mathlib.h"
#include "QF/quakefs.h"
#include "QF/sys.h"

#include "vis.h"
#include "options.h"

static int
CheckStack (cluster_t *cluster, threaddata_t *thread)
{
	pstack_t   *portal;

	for (portal = thread->pstack_head.next; portal; portal = portal->next) {
		if (portal->cluster == cluster) {
			printf ("CheckStack: cluster recursion\n");
			return 1;
		}
		if (!portal->cluster)
			break;
	}
	return 0;
}

static pstack_t *
new_stack (threaddata_t *td)
{
	pstack_t   *stack;

	stack = malloc (sizeof (pstack_t));
	stack->next = 0;
	stack->mightsee = set_new_size_r (&td->set_pool, portalclusters);
	return stack;
}

static sep_t *
new_separator (threaddata_t *thread)
{
	sep_t      *sep;

	ALLOC (128, sep_t, thread->sep, sep);
	return sep;
}

static void
delete_separator (threaddata_t *thread, sep_t *sep)
{
	FREE (thread->sep, sep);
}

static void
free_separators (threaddata_t *thread, sep_t *sep_list)
{
	while (sep_list) {
		sep_t      *sep = sep_list;
		sep_list = sep->next;
		delete_separator (thread, sep);
	}
}

static inline int
test_zero (float d)
{
	if (d < -ON_EPSILON)
		return -1;
	else if (d > ON_EPSILON)
		return 1;
	return 0;
}

static int
calc_plane (const vec3_t v1, const vec3_t v2, int flip, const vec3_t p,
			plane_t *plane)
{
	vec_t       length;

	if (flip < 0) {
		//CrossProduct (v2, v1, plane.normal);
		plane->normal[0] = v2[1] * v1[2] - v2[2] * v1[1];
		plane->normal[1] = v2[2] * v1[0] - v2[0] * v1[2];
		plane->normal[2] = v2[0] * v1[1] - v2[1] * v1[0];
	} else {
		//CrossProduct (v1, v2, plane.normal);
		plane->normal[0] = v1[1] * v2[2] - v1[2] * v2[1];
		plane->normal[1] = v1[2] * v2[0] - v1[0] * v2[2];
		plane->normal[2] = v1[0] * v2[1] - v1[1] * v2[0];
	}

	length = DotProduct (plane->normal, plane->normal);

	// if points don't make a valid plane, skip it
	if (length < ON_EPSILON)
		return 0;

	length = 1 / sqrt (length);
	VectorScale (plane->normal, length, plane->normal);
	plane->dist = DotProduct (p, plane->normal);
	return 1;
}

static inline int
test_plane (const plane_t *plane, const winding_t *pass, int index)
{
	int         s1, s2;
	int         k;
	vec_t       d;

	k = (index + 1) % pass->numpoints;
	d = DotProduct (pass->points[k], plane->normal) - plane->dist;
	s1 = test_zero (d);
	k = (index + pass->numpoints - 1) % pass->numpoints;
	d = DotProduct (pass->points[k], plane->normal) - plane->dist;
	s2 = test_zero (d);
	if (s1 == 0 && s2 == 0)
		return 0;
	if (s1 < 0 || s2 < 0)
		return 0;
	return 1;
}

static inline sep_t *
create_separator (threaddata_t *thread, const plane_t *src_pl,
				  const vec3_t p1, const vec3_t v1,
				  const winding_t *pass, int index, int flip)
{
	int         fliptest;
	vec_t       d;
	vec3_t      v2;
	plane_t     plane;
	sep_t      *sep;

	d = DotProduct (pass->points[index], src_pl->normal) - src_pl->dist;
	if ((fliptest = test_zero (d)) == 0)
		return 0;	// The point lies in the source plane

	VectorSubtract (pass->points[index], p1, v2);
	if (!calc_plane (v1, v2, fliptest, pass->points[index], &plane))
		return 0;	// point does not form a valid plane

	if (!test_plane (&plane, pass, index))
		return 0;	// not the right point

	sep = new_separator (thread);
	// flip the normal if we want the back side
	if (flip) {
		VectorNegate (plane.normal, sep->plane.normal);
		sep->plane.dist = -plane.dist;
	} else {
		sep->plane = plane;
	}
	return sep;
}

/*
	Find the planes separating source from pass. The planes form a double
	pyramid with source as the base (ie, source's edges will all be in one
	plane each) and the vertex of the pyramid is between source and pass.
	Edges from pass may or may not be in a plane, but each vertex will be in
	at least one plane.

	If flip is false, the planes will be such that the space enclosed by the
	planes and on the pass side of the vertex are on the front sides of the
	planes. If flip is true, then the space on the source side of the vertex
	and enclosed by the planes is on the front side of the planes.

		// find a vertex of pass that makes a plane that puts all of the
		// vertexes of pass on the front side and all of the vertexes of
		// source on the back side
*/
static sep_t *
FindSeparators (threaddata_t *thread,
				const winding_t *source, const plane_t src_pl,
				const winding_t *pass, int flip)
{
	int         i, j, l;
	vec3_t      v1;

	sep_t      *separators = 0, *sep;

	for (i = 0; i < source->numpoints; i++) {
		l = (i + 1) % source->numpoints;
		VectorSubtract (source->points[l], source->points[i], v1);

		for (j = 0; j < pass->numpoints; j++) {
			sep = create_separator (thread, &src_pl, source->points[i], v1,
									pass, j, flip);
			if (sep) {
				sep->next = separators;
				separators = sep;
				break;
			}
		}
	}
	return separators;
}

static winding_t *
ClipToSeparators (const sep_t *separators, winding_t *target)
{
	const sep_t *sep;

	for (sep = separators; target && sep; sep = sep->next) {
		target = ClipWinding (target, &sep->plane, false);
	}
	return target;
}

static inline set_t *
select_test_set (portal_t *portal, threaddata_t *thread)
{
	set_t      *test;

	if (portal->status == stat_done) {
		thread->stats.vistest++;
		test = portal->visbits;
	} else {
		thread->stats.mighttest++;
		test = portal->mightsee;
	}
	return test;
}

static inline int
mightsee_more (set_t *might, const set_t *prev_might, const set_t *test,
			   const set_t *vis)
{
	unsigned    i;
	set_bits_t  more = 0;

	// might = intersection (prev_might, test)
	// more = (might is not a subset of vis)
	for (i = 0; i < SET_WORDS (might); i++) {
		might->map[i] = prev_might->map[i] & test->map[i];
		more |= might->map[i] & ~vis->map[i];
	}
	return more != 0;
}

/*
	RecursiveClusterFlow

	Flood fill through the clusters
	If src_portal is NULL, this is the originating cluster
*/
static void
RecursiveClusterFlow (int clusternum, threaddata_t *thread, pstack_t *prevstack)
{
	int         i;
	set_t      *might;
	const set_t *test, *vis;
	cluster_t  *cluster;
	pstack_t   *stack;
	portal_t   *target_portal;
	plane_t     backplane;
	const plane_t *source_plane, *pass_plane;
	const winding_t *pass_winding;
	winding_t  *source_winding, *target_winding;

	thread->stats.chains++;

	if (!prevstack->next)
		prevstack->next = new_stack (thread);
	stack = prevstack->next;
	stack->cluster = 0;

	cluster = &clusters[clusternum];
	if (CheckStack(cluster, thread))
		return;

	// mark the cluster as visible
	if (!set_is_member (thread->clustervis, clusternum)) {
		set_add (thread->clustervis, clusternum);
		thread->base->numcansee++;
	}

	stack->cluster = cluster;
	stack->pass_portal = NULL;
	stack->separators[0] = 0;
	stack->separators[1] = 0;
	might = stack->mightsee;
	vis = thread->clustervis;

	source_plane = &thread->pstack_head.pass_plane;
	pass_winding = prevstack->pass_winding;
	pass_plane = &prevstack->pass_plane;

	// check all portals for flowing into other clusters
	for (i = 0; i < cluster->numportals; i++) {
		target_portal = cluster->portals[i];

		if (!set_is_member (prevstack->mightsee, target_portal->cluster))
			continue;		// can't possibly see it

		// if target_portal can't see anything we haven't already seen, skip it
		test = select_test_set (target_portal, thread);
		if (!mightsee_more (might, prevstack->mightsee, test, vis)) {
			// can't see anything new
			continue;
		}

		// get plane of target_portal, point normal into the neighbor cluster
		VectorNegate (target_portal->plane.normal, backplane.normal);
		backplane.dist = -target_portal->plane.dist;

		if (_VectorCompare (pass_plane->normal, backplane.normal))
			continue;		// can't go out a coplanar face

		thread->stats.portalcheck++;

		target_winding = target_portal->winding;
		target_winding = ClipWinding (target_winding, source_plane, false);
		if (!target_winding)
			continue;

		if (!pass_winding) {
			// the second cluster can be blocked only if coplanar

			stack->source_winding = prevstack->source_winding;

			stack->pass_winding = target_winding;
			stack->pass_plane = target_portal->plane;
			stack->pass_portal = target_portal;

			RecursiveClusterFlow (target_portal->cluster, thread, stack);
			FreeWinding (target_winding);
			continue;
		}

		target_winding = ClipWinding (target_winding, pass_plane, false);
		if (!target_winding)
			continue;

		// copy source_winding because it likely is already a copy and thus
		// if it gets clipped away, earlier stack levels will get corrupted
		source_winding = CopyWinding (prevstack->source_winding);

		source_winding = ClipWinding (source_winding, &backplane, false);
		if (!source_winding) {
			FreeWinding (target_winding);
			continue;
		}

		thread->stats.portaltest++;
		thread->stats.targettested++;

		if (options.level > 0) {
			winding_t  *old = target_winding;
			if (!stack->separators[0])
				stack->separators[0] = FindSeparators (thread,
													   source_winding,
													   *source_plane,
													   pass_winding, 0);
			target_winding = ClipToSeparators (stack->separators[0],
											   target_winding);
			if (!target_winding) {
				thread->stats.targetclipped++;
				FreeWinding (source_winding);
				continue;
			}
			if (target_winding != old)
				thread->stats.targettrimmed++;
		}

		if (options.level > 1) {
			winding_t  *old = target_winding;
			if (!stack->separators[1])
				stack->separators[1] = FindSeparators (thread,
													   pass_winding,
													   *pass_plane,
													   source_winding, 1);
			target_winding = ClipToSeparators (stack->separators[1],
											   target_winding);
			if (!target_winding) {
				thread->stats.targetclipped++;
				FreeWinding (source_winding);
				continue;
			}
			if (target_winding != old)
				thread->stats.targettrimmed++;
		}

		thread->stats.sourcetested++;
		if (options.level > 2) {
			winding_t  *old = source_winding;
			sep_t      *sep;
			sep = FindSeparators (thread,
								  target_winding, target_portal->plane,
								  pass_winding, 0);
			source_winding = ClipToSeparators (sep, source_winding);
			free_separators (thread, sep);
			if (!source_winding) {
				thread->stats.sourceclipped++;
				FreeWinding (target_winding);
				continue;
			}
			if (source_winding != old)
				thread->stats.sourcetrimmed++;
		}

		if (options.level > 3) {
			winding_t  *old = source_winding;
			sep_t      *sep;
			sep = FindSeparators (thread, pass_winding, *pass_plane,
								  target_winding, 1);
			source_winding = ClipToSeparators (sep, source_winding);
			free_separators (thread, sep);
			if (!source_winding) {
				thread->stats.sourceclipped++;
				FreeWinding (target_winding);
				continue;
			}
			if (source_winding != old)
				thread->stats.sourcetrimmed++;
		}

		stack->source_winding = source_winding;
		stack->pass_winding = target_winding;

		stack->pass_plane = target_portal->plane;
		stack->pass_portal = target_portal;

		thread->stats.portalpass++;

		// flow through it for real
		RecursiveClusterFlow (target_portal->cluster, thread, stack);

		FreeWinding (source_winding);
		FreeWinding (target_winding);
	}
	free_separators (thread, stack->separators[1]);
	free_separators (thread, stack->separators[0]);
}

void
PortalFlow (threaddata_t *data, portal_t *portal)
{
	WRLOCK_PORTAL (portal);
	if (portal->status != stat_selected)
		Sys_Error ("PortalFlow: reflowed");
	portal->status = stat_working;
	UNLOCK_PORTAL (portal);

	portal->visbits = set_new_size_r (&data->set_pool, portalclusters);

	data->clustervis = portal->visbits;
	data->base = portal;

	data->pstack_head.cluster = 0;
	data->pstack_head.pass_portal = portal;
	data->pstack_head.source_winding = portal->winding;
	data->pstack_head.pass_winding = 0;
	data->pstack_head.pass_plane = portal->plane;
	data->pstack_head.mightsee = portal->mightsee;
	data->pstack_head.separators[0] = 0;
	data->pstack_head.separators[1] = 0;

	RecursiveClusterFlow (portal->cluster, data, &data->pstack_head);
}
