/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): none yet.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/blenkernel/intern/navmesh_conversion.c
 *  \ingroup bke
 */

#include <math.h>
#include <stdlib.h>

#include "MEM_guardedalloc.h"

#include "DNA_meshdata_types.h"

#include "BLI_utildefines.h"
#include "BLI_math.h"
#include "BLI_sort.h"

#include "BKE_navmesh_conversion.h"
#include "BKE_cdderivedmesh.h"

#include "recast-capi.h"

BLI_INLINE float area2(const float *a, const float *b, const float *c)
{
	return (b[0] - a[0]) * (c[2] - a[2]) - (c[0] - a[0]) * (b[2] - a[2]);
}

BLI_INLINE int left(const float *a, const float *b, const float *c)
{
	return area2(a, b, c) < 0;
}

int polyNumVerts(const unsigned short *p, const int vertsPerPoly)
{
	int i, nv = 0;
	for (i = 0; i < vertsPerPoly; i++) {
		if (p[i] == 0xffff)
			break;
		nv++;
	}
	return nv;
}

int polyIsConvex(const unsigned short *p, const int vertsPerPoly, const float *verts)
{
	int j, nv = polyNumVerts(p, vertsPerPoly);
	if (nv < 3)
		return 0;
	for (j = 0; j < nv; j++) {
		const float *v = &verts[3 * p[j]];
		const float *v_next = &verts[3 * p[(j + 1) % nv]];
		const float *v_prev = &verts[3 * p[(nv + j - 1) % nv]];
		if (!left(v_prev, v, v_next))
			return 0;

	}
	return 1;
}

/* XXX, could replace with #dist_to_line_segment_v3(), or add a squared version */
float distPointToSegmentSq(const float point[3], const float a[3], const float b[3])
{
	float abx[3], dx[3];
	float d, t;

	sub_v3_v3v3(abx, b, a);
	sub_v3_v3v3(dx, point, a);

	d = abx[0] * abx[0] + abx[2] * abx[2];
	t = abx[0] * dx[0] + abx[2] * dx[2];

	if (d > 0.0f)
		t /= d;
	if (t < 0.0f)
		t = 0.0f;
	else if (t > 1.0f)
		t = 1.0f;
	dx[0] = a[0] + t * abx[0] - point[0];
	dx[2] = a[2] + t * abx[2] - point[2];

	return dx[0] * dx[0] + dx[2] * dx[2];
}

int buildRawVertIndicesData(DerivedMesh *dm, int *nverts_r, float **verts_r,
                            int *ntris_r, unsigned short **tris_r, int **trisToFacesMap_r,
                            int **recastData)
{
	int vi, fi, triIdx;
	int nverts, ntris;
	int *trisToFacesMap;
	float *verts;
	unsigned short *tris, *tri;
	int nfaces;
	MFace *faces;

	nverts = dm->getNumVerts(dm);
	if (nverts >= 0xffff) {
		printf("Converting navmesh: Error! Too many vertices. Max number of vertices %d\n", 0xffff);
		return 0;
	}
	if (nverts == 0) {
		printf("Converting navmesh: Error! There are no vertices!\n");
		return 0;
	}

	verts = MEM_mallocN(sizeof(float[3]) * nverts, "buildRawVertIndicesData verts");
	dm->getVertCos(dm, (float(*)[3])verts);

	/* flip coordinates */
	for (vi = 0; vi < nverts; vi++) {
		SWAP(float, verts[3 * vi + 1], verts[3 * vi + 2]);
	}

	/* calculate number of tris */
	dm->recalcTessellation(dm);
	nfaces = dm->getNumTessFaces(dm);
	if (nfaces == 0) {
		printf("Converting navmesh: Error! There are %i vertices, but no faces!\n", nverts);
		return 0;
	}

	faces = dm->getTessFaceArray(dm);
	ntris = nfaces;
	for (fi = 0; fi < nfaces; fi++) {
		MFace *face = &faces[fi];
		if (face->v4)
			ntris++;
	}

	/* copy and transform to triangles (reorder on the run) */
	trisToFacesMap = MEM_callocN(sizeof(int) * ntris, "buildRawVertIndicesData trisToFacesMap");
	tris = MEM_callocN(sizeof(unsigned short) * 3 * ntris, "buildRawVertIndicesData tris");
	tri = tris;
	triIdx = 0;
	for (fi = 0; fi < nfaces; fi++) {
		MFace *face = &faces[fi];
		tri[3 * triIdx + 0] = (unsigned short) face->v1;
		tri[3 * triIdx + 1] = (unsigned short) face->v3;
		tri[3 * triIdx + 2] = (unsigned short) face->v2;
		trisToFacesMap[triIdx++] = fi;
		if (face->v4) {
			tri[3 * triIdx + 0] = (unsigned short) face->v1;
			tri[3 * triIdx + 1] = (unsigned short) face->v4;
			tri[3 * triIdx + 2] = (unsigned short) face->v3;
			trisToFacesMap[triIdx++] = fi;
		}
	}

	/* carefully, recast data is just reference to data in derived mesh */
	*recastData = (int *)CustomData_get_layer(&dm->polyData, CD_RECAST);

	*nverts_r = nverts;
	*verts_r = verts;
	*ntris_r = ntris;
	*tris_r = tris;
	*trisToFacesMap_r = trisToFacesMap;

	return 1;
}

int buildPolygonsByDetailedMeshes(const int vertsPerPoly, const int npolys,
                                  unsigned short *polys, const unsigned short *dmeshes,
                                  const float *verts, const unsigned short *dtris,
                                  const int *dtrisToPolysMap)
{
	int polyidx;
	int capacity = vertsPerPoly;
	unsigned short *newPoly = MEM_callocN(sizeof(unsigned short) * capacity, "buildPolygonsByDetailedMeshes newPoly");
	memset(newPoly, 0xff, sizeof(unsigned short) * capacity);

	for (polyidx = 0; polyidx < npolys; polyidx++) {
		size_t i;
		int j, k;
		int nv = 0;
		/* search border */
		int tri, btri = -1;
		int edge, bedge = -1;
		int dtrisNum = dmeshes[polyidx * 4 + 3];
		int dtrisBase = dmeshes[polyidx * 4 + 2];
		unsigned char *traversedTris = MEM_callocN(sizeof(unsigned char) * dtrisNum, "buildPolygonsByDetailedMeshes traversedTris");
		unsigned short *adjustedPoly;
		int adjustedNv;
		int allBorderTraversed;

		for (j = 0; j < dtrisNum && btri == -1; j++) {
			int curpolytri = dtrisBase + j;
			for (k = 0; k < 3; k++) {
				unsigned short neighbortri = dtris[curpolytri * 3 * 2 + 3 + k];
				if (neighbortri == 0xffff || dtrisToPolysMap[neighbortri] != polyidx + 1) {
					btri = curpolytri;
					bedge = k;
					break;
				}
			}
		}
		if (btri == -1 || bedge == -1) {
			/* can't find triangle with border edge */
			MEM_freeN(traversedTris);
			MEM_freeN(newPoly);

			return 0;
		}

		newPoly[nv++] = dtris[btri * 3 * 2 + bedge];
		tri = btri;
		edge = (bedge + 1) % 3;
		traversedTris[tri - dtrisBase] = 1;
		while (tri != btri || edge != bedge) {
			int neighbortri = dtris[tri * 3 * 2 + 3 + edge];
			if (neighbortri == 0xffff || dtrisToPolysMap[neighbortri] != polyidx + 1) {
				if (nv == capacity) {
					unsigned short *newPolyBig;
					capacity += vertsPerPoly;
					newPolyBig = MEM_callocN(sizeof(unsigned short) * capacity, "buildPolygonsByDetailedMeshes newPolyBig");
					memset(newPolyBig, 0xff, sizeof(unsigned short) * capacity);
					memcpy(newPolyBig, newPoly, sizeof(unsigned short) * nv);
					MEM_freeN(newPoly);
					newPoly = newPolyBig;
				}
				newPoly[nv++] = dtris[tri * 3 * 2 + edge];
				/* move to next edge */
				edge = (edge + 1) % 3;
			}
			else {
				/* move to next tri */
				int twinedge = -1;
				for (k = 0; k < 3; k++) {
					if (dtris[neighbortri * 3 * 2 + 3 + k] == tri) {
						twinedge = k;
						break;
					}
				}
				if (twinedge == -1) {
					printf("Converting navmesh: Error! Can't find neighbor edge - invalid adjacency info\n");
					MEM_freeN(traversedTris);
					goto returnLabel;
				}
				tri = neighbortri;
				edge = (twinedge + 1) % 3;
				traversedTris[tri - dtrisBase] = 1;
			}
		}

		adjustedPoly = MEM_callocN(sizeof(unsigned short) * nv, "buildPolygonsByDetailedMeshes adjustedPoly");
		adjustedNv = 0;
		for (i = 0; i < nv; i++) {
			unsigned short prev = newPoly[(nv + i - 1) % nv];
			unsigned short cur = newPoly[i];
			unsigned short next = newPoly[(i + 1) % nv];
			float distSq = distPointToSegmentSq(&verts[3 * cur], &verts[3 * prev], &verts[3 * next]);
			static const float tolerance = 0.001f;
			if (distSq > tolerance)
				adjustedPoly[adjustedNv++] = cur;
		}
		memcpy(newPoly, adjustedPoly, adjustedNv * sizeof(unsigned short));
		MEM_freeN(adjustedPoly);
		nv = adjustedNv;

		allBorderTraversed = 1;
		for (i = 0; i < dtrisNum; i++) {
			if (traversedTris[i] == 0) {
				/* check whether it has border edges */
				int curpolytri = dtrisBase + i;
				for (k = 0; k < 3; k++) {
					unsigned short neighbortri = dtris[curpolytri * 3 * 2 + 3 + k];
					if (neighbortri == 0xffff || dtrisToPolysMap[neighbortri] != polyidx + 1) {
						allBorderTraversed = 0;
						break;
					}
				}
			}
		}

		if (nv <= vertsPerPoly && allBorderTraversed) {
			for (i = 0; i < nv; i++) {
				polys[polyidx * vertsPerPoly * 2 + i] = newPoly[i];
			}
		}

		MEM_freeN(traversedTris);
	}

returnLabel:
	MEM_freeN(newPoly);

	return 1;
}

struct SortContext {
	const int *recastData;
	const int *trisToFacesMap;
};

static int compareByData(const void *a, const void *b, void *ctx)
{
	return (((struct SortContext *)ctx)->recastData[((struct SortContext *)ctx)->trisToFacesMap[*(int *)a]] -
	        ((struct SortContext *)ctx)->recastData[((struct SortContext *)ctx)->trisToFacesMap[*(int *)b]]);
}

int buildNavMeshData(const int nverts, const float *verts,
                     const int ntris, const unsigned short *tris,
                     const int *recastData, const int *trisToFacesMap,
                     int *ndtris_r, unsigned short **dtris_r,
                     int *npolys_r, unsigned short **dmeshes_r, unsigned short **polys_r,
                     int *vertsPerPoly_r, int **dtrisToPolysMap_r, int **dtrisToTrisMap_r)

{
	int *trisMapping;
	int i;
	struct SortContext context;
	int validTriStart, prevPolyIdx, curPolyIdx, newPolyIdx, prevpolyidx;
	unsigned short *dmesh;

	int ndtris, npolys, vertsPerPoly;
	unsigned short *dtris, *dmeshes, *polys;
	int *dtrisToPolysMap, *dtrisToTrisMap;

	if (!recastData) {
		printf("Converting navmesh: Error! Can't find recast custom data\n");
		return 0;
	}

	trisMapping = MEM_callocN(sizeof(int) * ntris, "buildNavMeshData trisMapping");

	/* sort the triangles by polygon idx */
	for (i = 0; i < ntris; i++)
		trisMapping[i] = i;
	context.recastData = recastData;
	context.trisToFacesMap = trisToFacesMap;
	BLI_qsort_r(trisMapping, ntris, sizeof(int), compareByData, &context);

	/* search first valid triangle - triangle of convex polygon */
	validTriStart = -1;
	for (i = 0; i < ntris; i++) {
		if (recastData[trisToFacesMap[trisMapping[i]]] > 0) {
			validTriStart = i;
			break;
		}
	}

	if (validTriStart < 0) {
		printf("Converting navmesh: Error! No valid polygons in mesh\n");
		MEM_freeN(trisMapping);
		return 0;
	}

	ndtris = ntris - validTriStart;
	/* fill dtris to faces mapping */
	dtrisToTrisMap = MEM_callocN(sizeof(int) * ndtris, "buildNavMeshData dtrisToTrisMap");
	memcpy(dtrisToTrisMap, &trisMapping[validTriStart], ndtris * sizeof(int));
	MEM_freeN(trisMapping);

	/* create detailed mesh triangles  - copy only valid triangles
	 * and reserve memory for adjacency info */
	dtris = MEM_callocN(sizeof(unsigned short) * 3 * 2 * ndtris, "buildNavMeshData dtris");
	memset(dtris, 0xff, sizeof(unsigned short) * 3 * 2 * ndtris);
	for (i = 0; i < ndtris; i++) {
		memcpy(dtris + 3 * 2 * i, tris + 3 * dtrisToTrisMap[i], sizeof(unsigned short) * 3);
	}

	/* create new recast data corresponded to dtris and renumber for continuous indices */
	prevPolyIdx = -1;
	newPolyIdx = 0;
	dtrisToPolysMap = MEM_callocN(sizeof(int) * ndtris, "buildNavMeshData dtrisToPolysMap");
	for (i = 0; i < ndtris; i++) {
		curPolyIdx = recastData[trisToFacesMap[dtrisToTrisMap[i]]];
		if (curPolyIdx != prevPolyIdx) {
			newPolyIdx++;
			prevPolyIdx = curPolyIdx;
		}
		dtrisToPolysMap[i] = newPolyIdx;
	}


	/* build adjacency info for detailed mesh triangles */
	if (!recast_buildMeshAdjacency(dtris, ndtris, nverts, 3)) {
		printf("Converting navmesh: Error! Unable to build mesh adjacency information\n");
		MEM_freeN(trisMapping);
		MEM_freeN(dtrisToPolysMap);
		return 0;
	}

	/* create detailed mesh description for each navigation polygon */
	npolys = dtrisToPolysMap[ndtris - 1];
	dmeshes = MEM_callocN(sizeof(unsigned short) * npolys * 4, "buildNavMeshData dmeshes");
	memset(dmeshes, 0, npolys * 4 * sizeof(unsigned short));
	dmesh = NULL;
	prevpolyidx = 0;
	for (i = 0; i < ndtris; i++) {
		int curpolyidx = dtrisToPolysMap[i];
		if (curpolyidx != prevpolyidx) {
			if (curpolyidx != prevpolyidx + 1) {
				printf("Converting navmesh: Error! Wrong order of detailed mesh faces\n");
				goto fail;
			}
			dmesh = dmesh == NULL ? dmeshes : dmesh + 4;
			dmesh[2] = (unsigned short)i;  /* tbase */
			dmesh[3] = 0;  /* tnum */
			prevpolyidx = curpolyidx;
		}
		dmesh[3]++;
	}

	/* create navigation polygons */
	vertsPerPoly = 6;
	polys = MEM_callocN(sizeof(unsigned short) * npolys * vertsPerPoly * 2, "buildNavMeshData polys");
	memset(polys, 0xff, sizeof(unsigned short) * vertsPerPoly * 2 * npolys);

	if (!buildPolygonsByDetailedMeshes(vertsPerPoly, npolys, polys, dmeshes, verts, dtris, dtrisToPolysMap)) {
		printf("Converting navmesh: Error! Unable to build polygons from detailed mesh\n");
		goto fail;
	}

	*ndtris_r = ndtris;
	*npolys_r = npolys;
	*vertsPerPoly_r = vertsPerPoly;
	*dtris_r = dtris;
	*dmeshes_r = dmeshes;
	*polys_r = polys;
	*dtrisToPolysMap_r = dtrisToPolysMap;
	*dtrisToTrisMap_r = dtrisToTrisMap;

	return 1;

fail:
	MEM_freeN(dmeshes);
	MEM_freeN(dtrisToPolysMap);
	MEM_freeN(dtrisToTrisMap);
	return 0;
}


int buildNavMeshDataByDerivedMesh(DerivedMesh *dm, int *vertsPerPoly,
                                  int *nverts, float **verts,
                                  int *ndtris, unsigned short **dtris,
                                  int *npolys, unsigned short **dmeshes,
                                  unsigned short **polys, int **dtrisToPolysMap,
                                  int **dtrisToTrisMap, int **trisToFacesMap)
{
	int res;
	int ntris = 0, *recastData = NULL;
	unsigned short *tris = NULL;

	res = buildRawVertIndicesData(dm, nverts, verts, &ntris, &tris, trisToFacesMap, &recastData);
	if (!res) {
		printf("Converting navmesh: Error! Can't get raw vertices and indices from mesh\n");
		goto exit;
	}

	res = buildNavMeshData(*nverts, *verts, ntris, tris, recastData, *trisToFacesMap,
	                       ndtris, dtris, npolys, dmeshes, polys, vertsPerPoly,
	                       dtrisToPolysMap, dtrisToTrisMap);
	if (!res) {
		printf("Converting navmesh: Error! Can't build navmesh data from mesh\n");
		goto exit;
	}

exit:
	if (tris)
		MEM_freeN(tris);

	return res;
}

int polyFindVertex(const unsigned short *p, const int vertsPerPoly, unsigned short vertexIdx)
{
	int i, res = -1;
	for (i = 0; i < vertsPerPoly; i++) {
		if (p[i] == 0xffff)
			break;
		if (p[i] == vertexIdx) {
			res = i;
			break;
		}
	}
	return res;
}