/*
 * ***** 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) 2011 by Bastien Montagne.
 * All rights reserved.
 *
 * Contributor(s): None yet.
 *
 * ***** END GPL LICENSE BLOCK *****
 *
 */

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

#include "BLI_utildefines.h"
#include "BLI_ghash.h"
#include "BLI_listbase.h"
#include "BLI_math.h"
#include "BLI_rand.h"
#include "BLI_task.h"

#include "DNA_mesh_types.h"
#include "DNA_meshdata_types.h"
#include "DNA_modifier_types.h"
#include "DNA_object_types.h"

#include "BKE_cdderivedmesh.h"
#include "BKE_curve.h"
#include "BKE_customdata.h"
#include "BKE_deform.h"
#include "BKE_library.h"
#include "BKE_library_query.h"
#include "BKE_mesh.h"
#include "BKE_modifier.h"
#include "BKE_texture.h"          /* Texture masking. */

#include "DEG_depsgraph_build.h"

#include "MEM_guardedalloc.h"

#include "MOD_weightvg_util.h"
#include "MOD_modifiertypes.h"
#include "MOD_util.h"

//#define USE_TIMEIT

#ifdef USE_TIMEIT
#  include "PIL_time.h"
#  include "PIL_time_utildefines.h"
#endif

/**************************************
 * Util functions.                    *
 **************************************/

/* Util macro. */
#define OUT_OF_MEMORY() ((void)printf("WeightVGProximity: Out of memory.\n"))

typedef struct Vert2GeomData {
	/* Read-only data */
	float (*v_cos)[3];

	const SpaceTransform *loc2trgt;

	BVHTreeFromMesh *treeData[3];

	/* Write data, but not needing locking (two different threads will never write same index). */
	float *dist[3];
} Vert2GeomData;

/* Data which is localized to each computed chunk (i.e. thread-safe, and with continous subset of index range). */
typedef struct Vert2GeomDataChunk {
	/* Read-only data */
	float last_hit_co[3][3];
	bool is_init[3];
} Vert2GeomDataChunk;

/**
 * Callback used by BLI_task 'for loop' helper.
 */
static void vert2geom_task_cb_ex(
        void *__restrict userdata,
        const int iter,
        const ParallelRangeTLS *__restrict tls)
{
	Vert2GeomData *data = userdata;
	Vert2GeomDataChunk *data_chunk = tls->userdata_chunk;

	float tmp_co[3];
	int i;

	/* Convert the vertex to tree coordinates. */
	copy_v3_v3(tmp_co, data->v_cos[iter]);
	BLI_space_transform_apply(data->loc2trgt, tmp_co);

	for (i = 0; i < ARRAY_SIZE(data->dist); i++) {
		if (data->dist[i]) {
			BVHTreeNearest nearest = {0};

			/* Note that we use local proximity heuristics (to reduce the nearest search).
			 *
			 * If we already had an hit before in same chunk of tasks (i.e. previous vertex by index),
			 * we assume this vertex is going to have a close hit to that other vertex, so we can initiate
			 * the "nearest.dist" with the expected value to that last hit.
			 * This will lead in pruning of the search tree.
			 */
			nearest.dist_sq = data_chunk->is_init[i] ? len_squared_v3v3(tmp_co, data_chunk->last_hit_co[i]) : FLT_MAX;
			nearest.index = -1;

			/* Compute and store result. If invalid (-1 idx), keep FLT_MAX dist. */
			BLI_bvhtree_find_nearest(data->treeData[i]->tree, tmp_co, &nearest,
			                         data->treeData[i]->nearest_callback, data->treeData[i]);
			data->dist[i][iter] = sqrtf(nearest.dist_sq);

			if (nearest.index != -1) {
				copy_v3_v3(data_chunk->last_hit_co[i], nearest.co);
				data_chunk->is_init[i] = true;
			}
		}
	}
}

/**
 * Find nearest vertex and/or edge and/or face, for each vertex (adapted from shrinkwrap.c).
 */
static void get_vert2geom_distance(
        int numVerts, float (*v_cos)[3],
        float *dist_v, float *dist_e, float *dist_f,
        Mesh *target, const SpaceTransform *loc2trgt)
{
	Vert2GeomData data = {0};
	Vert2GeomDataChunk data_chunk = {{{0}}};

	BVHTreeFromMesh treeData_v = {NULL};
	BVHTreeFromMesh treeData_e = {NULL};
	BVHTreeFromMesh treeData_f = {NULL};

	if (dist_v) {
		/* Create a bvh-tree of the given target's verts. */
		BKE_bvhtree_from_mesh_get(&treeData_v, target, BVHTREE_FROM_VERTS, 2);
		if (treeData_v.tree == NULL) {
			OUT_OF_MEMORY();
			return;
		}
	}
	if (dist_e) {
		/* Create a bvh-tree of the given target's edges. */
		BKE_bvhtree_from_mesh_get(&treeData_e, target, BVHTREE_FROM_EDGES, 2);
		if (treeData_e.tree == NULL) {
			OUT_OF_MEMORY();
			return;
		}
	}
	if (dist_f) {
		/* Create a bvh-tree of the given target's faces. */
		BKE_bvhtree_from_mesh_get(&treeData_f, target, BVHTREE_FROM_LOOPTRI, 2);
		if (treeData_f.tree == NULL) {
			OUT_OF_MEMORY();
			return;
		}
	}

	data.v_cos = v_cos;
	data.loc2trgt = loc2trgt;
	data.treeData[0] = &treeData_v;
	data.treeData[1] = &treeData_e;
	data.treeData[2] = &treeData_f;
	data.dist[0] = dist_v;
	data.dist[1] = dist_e;
	data.dist[2] = dist_f;

	ParallelRangeSettings settings;
	BLI_parallel_range_settings_defaults(&settings);
	settings.use_threading = (numVerts > 10000);
	settings.userdata_chunk = &data_chunk;
	settings.userdata_chunk_size = sizeof(data_chunk);
	BLI_task_parallel_range(
	        0, numVerts,
	        &data,
	        vert2geom_task_cb_ex,
	        &settings);

	if (dist_v)
		free_bvhtree_from_mesh(&treeData_v);
	if (dist_e)
		free_bvhtree_from_mesh(&treeData_e);
	if (dist_f)
		free_bvhtree_from_mesh(&treeData_f);
}

/**
 * Returns the real distance between a vertex and another reference object.
 * Note that it works in final world space (i.e. with constraints etc. applied).
 */
static void get_vert2ob_distance(
        int numVerts, float (*v_cos)[3], float *dist,
        Object *ob, Object *obr)
{
	/* Vertex and ref object coordinates. */
	float v_wco[3];
	unsigned int i = numVerts;

	while (i-- > 0) {
		/* Get world-coordinates of the vertex (constraints and anim included). */
		mul_v3_m4v3(v_wco, ob->obmat, v_cos[i]);
		/* Return distance between both coordinates. */
		dist[i] = len_v3v3(v_wco, obr->obmat[3]);
	}
}

/**
 * Returns the real distance between an object and another reference object.
 * Note that it works in final world space (i.e. with constraints etc. applied).
 */
static float get_ob2ob_distance(const Object *ob, const Object *obr)
{
	return len_v3v3(ob->obmat[3], obr->obmat[3]);
}

/**
 * Maps distances to weights, with an optional "smoothing" mapping.
 */
static void do_map(Object *ob, float *weights, const int nidx, const float min_d, const float max_d, short mode)
{
	const float range_inv = 1.0f / (max_d - min_d); /* invert since multiplication is faster */
	unsigned int i = nidx;
	if (max_d == min_d) {
		while (i-- > 0) {
			weights[i] = (weights[i] >= max_d) ? 1.0f : 0.0f; /* "Step" behavior... */
		}
	}
	else if (max_d > min_d) {
		while (i-- > 0) {
			if     (weights[i] >= max_d) weights[i] = 1.0f;  /* most likely case first */
			else if (weights[i] <= min_d) weights[i] = 0.0f;
			else weights[i] = (weights[i] - min_d) * range_inv;
		}
	}
	else {
		while (i-- > 0) {
			if     (weights[i] <= max_d) weights[i] = 1.0f;  /* most likely case first */
			else if (weights[i] >= min_d) weights[i] = 0.0f;
			else weights[i] = (weights[i] - min_d) * range_inv;
		}
	}

	if (!ELEM(mode, MOD_WVG_MAPPING_NONE, MOD_WVG_MAPPING_CURVE)) {
		RNG *rng = NULL;

		if (mode == MOD_WVG_MAPPING_RANDOM) {
			rng = BLI_rng_new_srandom(BLI_ghashutil_strhash(ob->id.name + 2));
		}

		weightvg_do_map(nidx, weights, mode, NULL, rng);

		if (rng) {
			BLI_rng_free(rng);
		}
	}
}

/**************************************
 * Modifiers functions.               *
 **************************************/
static void initData(ModifierData *md)
{
	WeightVGProximityModifierData *wmd = (WeightVGProximityModifierData *) md;

	wmd->proximity_mode       = MOD_WVG_PROXIMITY_OBJECT;
	wmd->proximity_flags      = MOD_WVG_PROXIMITY_GEOM_VERTS;

	wmd->falloff_type         = MOD_WVG_MAPPING_NONE;

	wmd->mask_constant        = 1.0f;
	wmd->mask_tex_use_channel = MOD_WVG_MASK_TEX_USE_INT; /* Use intensity by default. */
	wmd->mask_tex_mapping     = MOD_DISP_MAP_LOCAL;
	wmd->max_dist             = 1.0f; /* vert arbitrary distance, but don't use 0 */
}

static CustomDataMask requiredDataMask(Object *UNUSED(ob), ModifierData *md)
{
	WeightVGProximityModifierData *wmd = (WeightVGProximityModifierData *) md;
	CustomDataMask dataMask = 0;

	/* We need vertex groups! */
	dataMask |= CD_MASK_MDEFORMVERT;

	/* Ask for UV coordinates if we need them. */
	if (wmd->mask_tex_mapping == MOD_DISP_MAP_UV)
		dataMask |= CD_MASK_MTFACE;

	/* No need to ask for CD_PREVIEW_MLOOPCOL... */

	return dataMask;
}

static bool dependsOnTime(ModifierData *md)
{
	WeightVGProximityModifierData *wmd = (WeightVGProximityModifierData *) md;

	if (wmd->mask_texture)
		return BKE_texture_dependsOnTime(wmd->mask_texture);
	return 0;
}

static void foreachObjectLink(ModifierData *md, Object *ob, ObjectWalkFunc walk, void *userData)
{
	WeightVGProximityModifierData *wmd = (WeightVGProximityModifierData *) md;
	walk(userData, ob, &wmd->proximity_ob_target, IDWALK_CB_NOP);
	walk(userData, ob, &wmd->mask_tex_map_obj, IDWALK_CB_NOP);
}

static void foreachIDLink(ModifierData *md, Object *ob, IDWalkFunc walk, void *userData)
{
	WeightVGProximityModifierData *wmd = (WeightVGProximityModifierData *) md;

	walk(userData, ob, (ID **)&wmd->mask_texture, IDWALK_CB_USER);

	foreachObjectLink(md, ob, (ObjectWalkFunc)walk, userData);
}

static void foreachTexLink(ModifierData *md, Object *ob, TexWalkFunc walk, void *userData)
{
	walk(userData, ob, md, "mask_texture");
}

static void updateDepsgraph(ModifierData *md, const ModifierUpdateDepsgraphContext *ctx)
{
	WeightVGProximityModifierData *wmd = (WeightVGProximityModifierData *)md;
	if (wmd->proximity_ob_target != NULL) {
		DEG_add_object_relation(ctx->node, wmd->proximity_ob_target, DEG_OB_COMP_TRANSFORM, "WeightVGProximity Modifier");
		DEG_add_object_relation(ctx->node, wmd->proximity_ob_target, DEG_OB_COMP_GEOMETRY, "WeightVGProximity Modifier");
	}
	if (wmd->mask_tex_map_obj != NULL && wmd->mask_tex_mapping == MOD_DISP_MAP_OBJECT) {
		DEG_add_object_relation(ctx->node, wmd->mask_tex_map_obj, DEG_OB_COMP_TRANSFORM, "WeightVGProximity Modifier");
		DEG_add_object_relation(ctx->node, wmd->mask_tex_map_obj, DEG_OB_COMP_GEOMETRY, "WeightVGProximity Modifier");
	}
	if (wmd->mask_tex_mapping == MOD_DISP_MAP_GLOBAL) {
		DEG_add_object_relation(ctx->node, ctx->object, DEG_OB_COMP_TRANSFORM, "WeightVGProximity Modifier");
		DEG_add_object_relation(ctx->node, ctx->object, DEG_OB_COMP_GEOMETRY, "WeightVGProximity Modifier");
	}
}

static bool isDisabled(ModifierData *md, int UNUSED(useRenderParams))
{
	WeightVGProximityModifierData *wmd = (WeightVGProximityModifierData *) md;
	/* If no vertex group, bypass. */
	if (wmd->defgrp_name[0] == '\0') return 1;
	/* If no target object, bypass. */
	return (wmd->proximity_ob_target == NULL);
}

static Mesh *applyModifier(ModifierData *md, const ModifierEvalContext *ctx, Mesh *mesh)
{
	BLI_assert(mesh != NULL);

	WeightVGProximityModifierData *wmd = (WeightVGProximityModifierData *) md;
	MDeformVert *dvert = NULL;
	MDeformWeight **dw, **tdw;
	float (*v_cos)[3] = NULL; /* The vertices coordinates. */
	Object *ob = ctx->object;
	Object *obr = NULL; /* Our target object. */
	int defgrp_index;
	float *tw = NULL;
	float *org_w = NULL;
	float *new_w = NULL;
	int *tidx, *indices = NULL;
	int numIdx = 0;
	int i;
	/* Flags. */
#if 0
	const bool do_prev = (wmd->modifier.mode & eModifierMode_DoWeightPreview) != 0;
#endif

#ifdef USE_TIMEIT
	TIMEIT_START(perf);
#endif

	/* Get number of verts. */
	const int numVerts = mesh->totvert;

	/* Check if we can just return the original mesh.
	 * Must have verts and therefore verts assigned to vgroups to do anything useful!
	 */
	if ((numVerts == 0) || BLI_listbase_is_empty(&ctx->object->defbase)) {
		return mesh;
	}

	/* Get our target object. */
	obr = wmd->proximity_ob_target;
	if (obr == NULL) {
		return mesh;
	}

	/* Get vgroup idx from its name. */
	defgrp_index = defgroup_name_index(ob, wmd->defgrp_name);
	if (defgrp_index == -1) {
		return mesh;
	}

	const bool has_mdef = CustomData_has_layer(&mesh->vdata, CD_MDEFORMVERT);
	/* If no vertices were ever added to an object's vgroup, dvert might be NULL. */
	/* As this modifier never add vertices to vgroup, just return. */
	if (!has_mdef) {
		return mesh;
	}

	Mesh *result = mesh;

	if (has_mdef) {
		dvert = CustomData_duplicate_referenced_layer(&result->vdata, CD_MDEFORMVERT, numVerts);
	}
	else {
		/* Add a valid data layer! */
		dvert = CustomData_add_layer(&result->vdata, CD_MDEFORMVERT, CD_CALLOC, NULL, numVerts);
	}
	/* Ultimate security check. */
	if (!dvert) {
		BKE_id_free(NULL, result);
		return mesh;
	}

	/* Find out which vertices to work on (all vertices in vgroup), and get their relevant weight. */
	tidx = MEM_malloc_arrayN(numVerts, sizeof(int), "WeightVGProximity Modifier, tidx");
	tw = MEM_malloc_arrayN(numVerts, sizeof(float), "WeightVGProximity Modifier, tw");
	tdw = MEM_malloc_arrayN(numVerts, sizeof(MDeformWeight *), "WeightVGProximity Modifier, tdw");
	for (i = 0; i < numVerts; i++) {
		MDeformWeight *_dw = defvert_find_index(&dvert[i], defgrp_index);
		if (_dw) {
			tidx[numIdx] = i;
			tw[numIdx] = _dw->weight;
			tdw[numIdx++] = _dw;
		}
	}
	/* If no vertices found, return org data! */
	if (numIdx == 0) {
		MEM_freeN(tidx);
		MEM_freeN(tw);
		MEM_freeN(tdw);
		BKE_id_free(NULL, result);
		return mesh;
	}
	if (numIdx != numVerts) {
		indices = MEM_malloc_arrayN(numIdx, sizeof(int), "WeightVGProximity Modifier, indices");
		memcpy(indices, tidx, sizeof(int) * numIdx);
		org_w = MEM_malloc_arrayN(numIdx, sizeof(float), "WeightVGProximity Modifier, org_w");
		memcpy(org_w, tw, sizeof(float) * numIdx);
		dw = MEM_malloc_arrayN(numIdx, sizeof(MDeformWeight *), "WeightVGProximity Modifier, dw");
		memcpy(dw, tdw, sizeof(MDeformWeight *) * numIdx);
		MEM_freeN(tw);
		MEM_freeN(tdw);
	}
	else {
		org_w = tw;
		dw = tdw;
	}
	new_w = MEM_malloc_arrayN(numIdx, sizeof(float), "WeightVGProximity Modifier, new_w");
	MEM_freeN(tidx);

	/* Get our vertex coordinates. */
	if (numIdx != numVerts) {
		float (*tv_cos)[3] = BKE_mesh_vertexCos_get(result, NULL);
		v_cos = MEM_malloc_arrayN(numIdx, sizeof(float[3]), "WeightVGProximity Modifier, v_cos");
		for (i = 0; i < numIdx; i++) {
			copy_v3_v3(v_cos[i], tv_cos[indices[i]]);
		}
		MEM_freeN(tv_cos);
	}
	else {
		v_cos = BKE_mesh_vertexCos_get(result, NULL);
	}

	/* Compute wanted distances. */
	if (wmd->proximity_mode == MOD_WVG_PROXIMITY_OBJECT) {
		const float dist = get_ob2ob_distance(ob, obr);
		for (i = 0; i < numIdx; i++) {
			new_w[i] = dist;
		}
	}
	else if (wmd->proximity_mode == MOD_WVG_PROXIMITY_GEOMETRY) {
		const bool use_trgt_verts = (wmd->proximity_flags & MOD_WVG_PROXIMITY_GEOM_VERTS) != 0;
		const bool use_trgt_edges = (wmd->proximity_flags & MOD_WVG_PROXIMITY_GEOM_EDGES) != 0;
		const bool use_trgt_faces = (wmd->proximity_flags & MOD_WVG_PROXIMITY_GEOM_FACES) != 0;

		if (use_trgt_verts || use_trgt_edges || use_trgt_faces) {
			bool target_mesh_free;
			Mesh *target_mesh = BKE_modifier_get_evaluated_mesh_from_evaluated_object(obr, &target_mesh_free);

			/* We must check that we do have a valid target_mesh! */
			if (target_mesh != NULL) {
				SpaceTransform loc2trgt;
				float *dists_v = use_trgt_verts ? MEM_malloc_arrayN(numIdx, sizeof(float), "dists_v") : NULL;
				float *dists_e = use_trgt_edges ? MEM_malloc_arrayN(numIdx, sizeof(float), "dists_e") : NULL;
				float *dists_f = use_trgt_faces ? MEM_malloc_arrayN(numIdx, sizeof(float), "dists_f") : NULL;

				BLI_SPACE_TRANSFORM_SETUP(&loc2trgt, ob, obr);
				get_vert2geom_distance(numIdx, v_cos, dists_v, dists_e, dists_f,
				                       target_mesh, &loc2trgt);
				for (i = 0; i < numIdx; i++) {
					new_w[i] = dists_v ? dists_v[i] : FLT_MAX;
					if (dists_e)
						new_w[i] = min_ff(dists_e[i], new_w[i]);
					if (dists_f)
						new_w[i] = min_ff(dists_f[i], new_w[i]);
				}

				MEM_SAFE_FREE(dists_v);
				MEM_SAFE_FREE(dists_e);
				MEM_SAFE_FREE(dists_f);

				if (target_mesh_free) {
					BKE_id_free(NULL, target_mesh);
				}
			}
			/* Else, fall back to default obj2vert behavior. */
			else {
				get_vert2ob_distance(numIdx, v_cos, new_w, ob, obr);
			}
		}
		else {
			get_vert2ob_distance(numIdx, v_cos, new_w, ob, obr);
		}
	}

	/* Map distances to weights. */
	do_map(ob, new_w, numIdx, wmd->min_dist, wmd->max_dist, wmd->falloff_type);

	/* Do masking. */
	weightvg_do_mask(ctx, numIdx, indices, org_w, new_w, ob, result, wmd->mask_constant,
	                 wmd->mask_defgrp_name, wmd->modifier.scene, wmd->mask_texture,
	                 wmd->mask_tex_use_channel, wmd->mask_tex_mapping,
	                 wmd->mask_tex_map_obj, wmd->mask_tex_uvlayer_name);

	/* Update vgroup. Note we never add nor remove vertices from vgroup here. */
	weightvg_update_vg(dvert, defgrp_index, dw, numIdx, indices, org_w, false, 0.0f, false, 0.0f);

	/* If weight preview enabled... */
#if 0 /* XXX Currently done in mod stack :/ */
	if (do_prev)
		DM_update_weight_mcol(ob, dm, 0, org_w, numIdx, indices);
#endif

	/* Freeing stuff. */
	MEM_freeN(org_w);
	MEM_freeN(new_w);
	MEM_freeN(dw);
	MEM_freeN(v_cos);
	MEM_SAFE_FREE(indices);

#ifdef USE_TIMEIT
	TIMEIT_END(perf);
#endif

	/* Return the vgroup-modified mesh. */
	return result;
}


ModifierTypeInfo modifierType_WeightVGProximity = {
	/* name */              "VertexWeightProximity",
	/* structName */        "WeightVGProximityModifierData",
	/* structSize */        sizeof(WeightVGProximityModifierData),
	/* type */              eModifierTypeType_NonGeometrical,
	/* flags */             eModifierTypeFlag_AcceptsMesh |
	                        eModifierTypeFlag_SupportsMapping |
	                        eModifierTypeFlag_SupportsEditmode |
	                        eModifierTypeFlag_UsesPreview,

	/* copyData */          modifier_copyData_generic,

	/* deformVerts_DM */    NULL,
	/* deformMatrices_DM */ NULL,
	/* deformVertsEM_DM */  NULL,
	/* deformMatricesEM_DM*/NULL,
	/* applyModifier_DM */  NULL,
	/* applyModifierEM_DM */NULL,

	/* deformVerts */       NULL,
	/* deformMatrices */    NULL,
	/* deformVertsEM */     NULL,
	/* deformMatricesEM */  NULL,
	/* applyModifier */     applyModifier,
	/* applyModifierEM */   NULL,

	/* initData */          initData,
	/* requiredDataMask */  requiredDataMask,
	/* freeData */          NULL,
	/* isDisabled */        isDisabled,
	/* updateDepsgraph */   updateDepsgraph,
	/* dependsOnTime */     dependsOnTime,
	/* dependsOnNormals */  NULL,
	/* foreachObjectLink */ foreachObjectLink,
	/* foreachIDLink */     foreachIDLink,
	/* foreachTexLink */    foreachTexLink,
};