/*
 * ***** 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) 2005 by the Blender Foundation.
 * All rights reserved.
 *
 * Contributor(s): Daniel Dunbar
 *                 Ton Roosendaal,
 *                 Ben Batt,
 *                 Brecht Van Lommel,
 *                 Campbell Barton
 *
 * ***** END GPL LICENSE BLOCK *****
 *
 */

/** \file blender/modifiers/intern/MOD_fluidsim_util.c
 *  \ingroup modifiers
 */


#include <stddef.h>
#include <zlib.h>

#include "DNA_object_types.h"
#include "DNA_scene_types.h"
#include "DNA_mesh_types.h"
#include "DNA_meshdata_types.h"
#include "DNA_object_fluidsim_types.h"

#include "BLI_blenlib.h"
#include "BLI_math.h"
#include "BLI_utildefines.h"

#include "BKE_fluidsim.h" /* ensure definitions here match */
#ifdef WITH_MOD_FLUID
#  include "BKE_global.h"
#endif
#include "BKE_library.h"
#include "BKE_main.h"
#include "BKE_mesh.h"

#include "DEG_depsgraph.h"
#include "DEG_depsgraph_query.h"

#include "MOD_fluidsim_util.h"
#include "MOD_modifiertypes.h"

#include "MEM_guardedalloc.h"

// headers for fluidsim bobj meshes
#include "LBM_fluidsim.h"


void fluidsim_init(FluidsimModifierData *fluidmd)
{
#ifdef WITH_MOD_FLUID
	if (fluidmd) {
		FluidsimSettings *fss = MEM_callocN(sizeof(FluidsimSettings), "fluidsimsettings");

		fluidmd->fss = fss;

		if (!fss)
			return;

		fss->fmd = fluidmd;
		fss->type = OB_FLUIDSIM_ENABLE;
		fss->threads = 0;
		fss->show_advancedoptions = 0;

		fss->resolutionxyz = 65;
		fss->previewresxyz = 45;
		fss->realsize = 0.5;
		fss->guiDisplayMode = OB_FSDOM_PREVIEW;
		fss->renderDisplayMode = OB_FSDOM_FINAL;

		fss->viscosityValue = 1.0;
		fss->viscosityExponent = 6;

		fss->grav[0] = 0.0;
		fss->grav[1] = 0.0;
		fss->grav[2] = -9.81;

		fss->animStart = 0.0;
		fss->animEnd = 4.0;
		fss->animRate = 1.0;
		fss->gstar = 0.005; // used as normgstar
		fss->maxRefine = -1;
		/* maxRefine is set according to resolutionxyz during bake */

		/* fluid/inflow settings
		 * fss->iniVel --> automatically set to 0 */

		modifier_path_init(fss->surfdataPath, sizeof(fss->surfdataPath), OB_FLUIDSIM_SURF_DIR_DEFAULT);

		/* first init of bounding box */
		/* no bounding box needed */

		/* todo - reuse default init from elbeem! */
		fss->typeFlags = OB_FSBND_PARTSLIP | OB_FSSG_NOOBS;
		fss->domainNovecgen = 0;
		fss->volumeInitType = 1; /* volume */
		fss->partSlipValue = 0.2;

		fss->generateTracers = 0;
		fss->generateParticles = 0.0;
		fss->surfaceSmoothing = 1.0;
		fss->surfaceSubdivs = 0.0;
		fss->particleInfSize = 0.0;
		fss->particleInfAlpha = 0.0;

		/* init fluid control settings */
		fss->attractforceStrength = 0.2;
		fss->attractforceRadius = 0.75;
		fss->velocityforceStrength = 0.2;
		fss->velocityforceRadius = 0.75;
		fss->cpsTimeStart = fss->animStart;
		fss->cpsTimeEnd = fss->animEnd;
		fss->cpsQuality = 10.0; // 1.0 / 10.0 => means 0.1 width

		/*
		 * BAD TODO: this is done in buttons_object.c in the moment
		 * Mesh *mesh = ob->data;
		 * // calculate bounding box
		 * fluid_get_bb(mesh->mvert, mesh->totvert, ob->obmat, fss->bbStart, fss->bbSize);
		 */

		fss->meshVelocities = NULL;

		fss->lastgoodframe = -1;

		fss->flag |= OB_FLUIDSIM_ACTIVE;

	}
#else
	(void)fluidmd; /* unused */
#endif
	return;
}

void fluidsim_free(FluidsimModifierData *fluidmd)
{
	if (fluidmd && fluidmd->fss) {
		if (fluidmd->fss->meshVelocities) {
			MEM_freeN(fluidmd->fss->meshVelocities);
		}
		MEM_SAFE_FREE(fluidmd->fss);
	}

	return;
}

#ifdef WITH_MOD_FLUID
/* read .bobj.gz file into a fluidsimMesh struct */
static Mesh *fluidsim_read_obj(const char *filename, const MPoly *mp_example)
{
	int wri = 0, i;
	int gotBytes;
	gzFile gzf;
	int numverts = 0, numfaces = 0;
	Mesh *mesh = NULL;
	MPoly *mp;
	MLoop *ml;
	MVert *mv;
	short *normals, *no_s;
	float no[3];

	const short mp_mat_nr = mp_example->mat_nr;
	const char mp_flag =   mp_example->flag;

	/* ------------------------------------------------
	 * get numverts + numfaces first
	 * ------------------------------------------------ */
	gzf = BLI_gzopen(filename, "rb");
	if (!gzf) {
		return NULL;
	}

	/* read numverts */
	gotBytes = gzread(gzf, &wri, sizeof(wri));
	numverts = wri;

	/* skip verts */
	gotBytes = gzseek(gzf, numverts * 3 * sizeof(float), SEEK_CUR) != -1;


	/* read number of normals */
	if (gotBytes)
		gotBytes = gzread(gzf, &wri, sizeof(wri));

	/* skip normals */
	gotBytes = gzseek(gzf, numverts * 3 * sizeof(float), SEEK_CUR) != -1;

	/* get no. of triangles */
	if (gotBytes)
		gotBytes = gzread(gzf, &wri, sizeof(wri));
	numfaces = wri;

	gzclose(gzf);
	/* ------------------------------------------------ */

	if (!numfaces || !numverts || !gotBytes)
		return NULL;

	gzf = BLI_gzopen(filename, "rb");
	if (!gzf) {
		return NULL;
	}

	mesh = BKE_mesh_new_nomain(numverts, 0, 0, numfaces * 3, numfaces);

	if (!mesh) {
		gzclose(gzf);
		return NULL;
	}

	/* read numverts */
	gotBytes = gzread(gzf, &wri, sizeof(wri));

	/* read vertex position from file */
	mv = mesh->mvert;

	for (i = 0; i < numverts; i++, mv++)
		gotBytes = gzread(gzf, mv->co, sizeof(float) * 3);

	/* should be the same as numverts */
	gotBytes = gzread(gzf, &wri, sizeof(wri));
	if (wri != numverts) {
		if (mesh)
			BKE_id_free(NULL, mesh);
		gzclose(gzf);
		return NULL;
	}

	normals = MEM_calloc_arrayN(numverts, 3 * sizeof(short), "fluid_tmp_normals");
	if (!normals) {
		if (mesh)
			BKE_id_free(NULL, mesh);
		gzclose(gzf);
		return NULL;
	}

	/* read normals from file (but don't save them yet) */
	for (i = numverts, no_s = normals; i > 0; i--, no_s += 3) {
		gotBytes = gzread(gzf, no, sizeof(float) * 3);
		normal_float_to_short_v3(no_s, no);
	}

	/* read no. of triangles */
	gotBytes = gzread(gzf, &wri, sizeof(wri));

	if (wri != numfaces) {
		printf("Fluidsim: error in reading data from file.\n");
		if (mesh)
			BKE_id_free(NULL, mesh);
		gzclose(gzf);
		MEM_freeN(normals);
		return NULL;
	}

	/* read triangles from file */
	mp = mesh->mpoly;
	ml = mesh->mloop;
	for (i = 0; i < numfaces; i++, mp++, ml += 3) {
		int face[3];

		gotBytes = gzread(gzf, face, sizeof(int) * 3);

		/* initialize from existing face */
		mp->mat_nr = mp_mat_nr;
		mp->flag =   mp_flag;

		mp->loopstart = i * 3;
		mp->totloop = 3;

		ml[0].v = face[0];
		ml[1].v = face[1];
		ml[2].v = face[2];

	}

	gzclose(gzf);

	BKE_mesh_calc_edges(mesh, false, false);
	BKE_mesh_apply_vert_normals(mesh, (short (*)[3])normals);
	MEM_freeN(normals);

	// CDDM_calc_normals(result);
	return mesh;
}


void fluid_get_bb(
        MVert *mvert, int totvert, float obmat[4][4],
        /*RET*/ float start[3], /*RET*/ float size[3])
{
	float bbsx = 0.0, bbsy = 0.0, bbsz = 0.0;
	float bbex = 1.0, bbey = 1.0, bbez = 1.0;
	int i;
	float vec[3];

	if (totvert == 0) {
		zero_v3(start);
		zero_v3(size);
		return;
	}

	copy_v3_v3(vec, mvert[0].co);
	mul_m4_v3(obmat, vec);
	bbsx = vec[0]; bbsy = vec[1]; bbsz = vec[2];
	bbex = vec[0]; bbey = vec[1]; bbez = vec[2];

	for (i = 1; i < totvert; i++) {
		copy_v3_v3(vec, mvert[i].co);
		mul_m4_v3(obmat, vec);

		if (vec[0] < bbsx) { bbsx = vec[0]; }
		if (vec[1] < bbsy) { bbsy = vec[1]; }
		if (vec[2] < bbsz) { bbsz = vec[2]; }
		if (vec[0] > bbex) { bbex = vec[0]; }
		if (vec[1] > bbey) { bbey = vec[1]; }
		if (vec[2] > bbez) { bbez = vec[2]; }
	}

	/* return values... */
	if (start) {
		start[0] = bbsx;
		start[1] = bbsy;
		start[2] = bbsz;
	}
	if (size) {
		size[0] = bbex - bbsx;
		size[1] = bbey - bbsy;
		size[2] = bbez - bbsz;
	}
}

//-------------------------------------------------------------------------------
// old interface
//-------------------------------------------------------------------------------

void fluid_estimate_memory(Object *ob, FluidsimSettings *fss, char *value)
{
	Mesh *mesh;

	value[0] = '\0';

	if (ob->type == OB_MESH) {
		/* use mesh bounding box and object scaling */
		mesh = ob->data;

		fluid_get_bb(mesh->mvert, mesh->totvert, ob->obmat, fss->bbStart, fss->bbSize);
		elbeemEstimateMemreq(fss->resolutionxyz, fss->bbSize[0], fss->bbSize[1], fss->bbSize[2], fss->maxRefine, value);
	}
}


/* read zipped fluidsim velocities into the co's of the fluidsimsettings normals struct */
static void fluidsim_read_vel_cache(FluidsimModifierData *fluidmd, Mesh *mesh, char *filename)
{
	int wri, i, j;
	float wrf;
	gzFile gzf;
	FluidsimSettings *fss = fluidmd->fss;
	int len = strlen(filename);
	int totvert = mesh->totvert;
	FluidVertexVelocity *velarray = NULL;

	/* mesh and vverts have to be valid from loading... */

	if (fss->meshVelocities)
		MEM_freeN(fss->meshVelocities);

	if (len < 7) {
		return;
	}

	if (fss->domainNovecgen > 0) return;

	fss->meshVelocities = MEM_calloc_arrayN(mesh->totvert, sizeof(FluidVertexVelocity), "Fluidsim_velocities");
	fss->totvert = totvert;

	velarray = fss->meshVelocities;

	/* .bobj.gz, correct filename
	 * 87654321 */
	filename[len - 6] = 'v';
	filename[len - 5] = 'e';
	filename[len - 4] = 'l';

	gzf = BLI_gzopen(filename, "rb");
	if (!gzf) {
		MEM_freeN(fss->meshVelocities);
		fss->meshVelocities = NULL;
		return;
	}

	gzread(gzf, &wri, sizeof(wri));
	if (wri != totvert) {
		MEM_freeN(fss->meshVelocities);
		fss->meshVelocities = NULL;
		return;
	}

	for (i = 0; i < totvert; i++) {
		for (j = 0; j < 3; j++) {
			gzread(gzf, &wrf, sizeof(wrf));
			velarray[i].vel[j] = wrf;
		}
	}

	gzclose(gzf);
}

static Mesh *fluidsim_read_cache(
        Object *ob, Mesh *orgmesh,
        FluidsimModifierData *fluidmd, int framenr, int useRenderParams)
{
	int curFrame = framenr /* - 1 */ /*scene->r.sfra*/; /* start with 0 at start frame */
	/*  why start with 0 as start frame?? Animations + time are frozen for frame 0 anyway. (See physics_fluid.c for that. - DG */
	/* If we start with frame 0, we need to remap all animation channels, too, because they will all be 1 frame late if using frame-1! - DG */

	char targetFile[FILE_MAX];
	FluidsimSettings *fss = fluidmd->fss;
	Mesh *newmesh = NULL;
	MPoly *mpoly;
	MPoly mp_example = {0};

	const int displaymode = useRenderParams ? fss->renderDisplayMode : fss->guiDisplayMode;

	switch (displaymode) {
		case OB_FSDOM_GEOM:
			/* just display original object */
			return NULL;
		case OB_FSDOM_PREVIEW:
			/* use preview mesh */
			BLI_join_dirfile(targetFile, sizeof(targetFile), fss->surfdataPath, OB_FLUIDSIM_SURF_PREVIEW_OBJ_FNAME);
			break;
		case OB_FSDOM_FINAL:
			/* use final mesh */
			BLI_join_dirfile(targetFile, sizeof(targetFile), fss->surfdataPath, OB_FLUIDSIM_SURF_FINAL_OBJ_FNAME);
			break;
		default:
			BLI_assert(!"Wrong fluidsim display type");
			return NULL;
	}

	/* offset baked frame */
	curFrame += fss->frameOffset;

	BLI_path_abs(targetFile, modifier_path_relbase_from_global(ob));
	BLI_path_frame(targetFile, curFrame, 0); // fixed #frame-no

	/* assign material + flags to new mesh.
	 * if there's no faces in original mesh, keep materials and flags unchanged */
	mpoly = orgmesh->mpoly;
	if (mpoly) {
		mp_example = *mpoly;
	}
	/* else leave NULL'd */

	newmesh = fluidsim_read_obj(targetFile, &mp_example);

	if (!newmesh) {
		/* switch, abort background rendering when fluidsim mesh is missing */
		const char *strEnvName2 = "BLENDER_ELBEEMBOBJABORT"; // from blendercall.cpp

		if (G.background == 1) {
			if (BLI_getenv(strEnvName2)) {
				int elevel = atoi(BLI_getenv(strEnvName2));
				if (elevel > 0) {
					printf("Env. var %s set, fluid sim mesh '%s' not found, aborting render...\n",
					       strEnvName2, targetFile);
					exit(1);
				}
			}
		}

		/* display org. object upon failure which is in new mesh */
		return NULL;
	}

	/* load vertex velocities, if they exist...
	 * TODO? use generate flag as loading flag as well?
	 * warning, needs original .bobj.gz mesh loading filename */
	if (displaymode == OB_FSDOM_FINAL) {
		fluidsim_read_vel_cache(fluidmd, newmesh, targetFile);
	}
	else {
		if (fss->meshVelocities)
			MEM_freeN(fss->meshVelocities);

		fss->meshVelocities = NULL;
	}

	return newmesh;
}
#endif // WITH_MOD_FLUID

Mesh *fluidsimModifier_do(
        FluidsimModifierData *fluidmd,
        const ModifierEvalContext *ctx,
        Mesh *mesh)
{
#ifdef WITH_MOD_FLUID
	Object *ob = ctx->object;
	Depsgraph *depsgraph = ctx->depsgraph;
	const bool useRenderParams = (ctx->flag & MOD_APPLY_RENDER) != 0;
//	const bool isFinalCalc = (ctx->flag & MOD_APPLY_USECACHE) != 0;
	Mesh *result = NULL;
	int framenr;
	FluidsimSettings *fss = NULL;

	framenr = (int)DEG_get_ctime(depsgraph);

	/* only handle fluidsim domains */
	if (fluidmd && fluidmd->fss && (fluidmd->fss->type != OB_FLUIDSIM_DOMAIN))
		return mesh;

	/* sanity check */
	if (!fluidmd || !fluidmd->fss)
		return mesh;

	fss = fluidmd->fss;

	/* timescale not supported yet
	 * clmd->sim_parms->timescale = timescale; */

	/* support reversing of baked fluid frames here */
	if ((fss->flag & OB_FLUIDSIM_REVERSE) && (fss->lastgoodframe >= 0)) {
		framenr = fss->lastgoodframe - framenr + 1;
		CLAMP(framenr, 1, fss->lastgoodframe);
	}

	/* try to read from cache */
	/* if the frame is there, fine, otherwise don't do anything */
	if ((result = fluidsim_read_cache(ob, mesh, fluidmd, framenr, useRenderParams)))
		return result;

	return mesh;
#else
	/* unused */
	UNUSED_VARS(fluidmd, ctx, mesh);
	return NULL;
#endif
}