/*
 * ***** 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) 2013 Blender Foundation
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): Joshua Leung, Sergej Reich
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file rigidbody.c
 *  \ingroup blenkernel
 *  \brief Blender-side interface and methods for dealing with Rigid Body simulations
 */

#include <stdio.h>
#include <string.h>
#include <stddef.h>
#include <float.h>
#include <math.h>
#include <limits.h>

#include "MEM_guardedalloc.h"

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

#include "RBI_api.h"

#include "DNA_anim_types.h"
#include "DNA_group_types.h"
#include "DNA_mesh_types.h"
#include "DNA_meshdata_types.h"
#include "DNA_object_types.h"
#include "DNA_object_force.h"
#include "DNA_rigidbody_types.h"
#include "DNA_scene_types.h"

#include "BKE_animsys.h"
#include "BKE_cdderivedmesh.h"
#include "BKE_effect.h"
#include "BKE_group.h"
#include "BKE_object.h"
#include "BKE_mesh.h"
#include "BKE_pointcache.h"
#include "BKE_rigidbody.h"
#include "BKE_global.h"
#include "BKE_utildefines.h"

#include "RNA_access.h"

/* ************************************** */
/* Memory Management */

/* Freeing Methods --------------------- */

/* Free rigidbody world */
void BKE_rigidbody_free_world(RigidBodyWorld *rbw)
{
	GroupObject *go;
	/* sanity check */
	if (!rbw)
		return;

	if (rbw->physics_world) {
		/* free physics references, we assume that all physics objects in will have been added to the world */
		if (rbw->group) {
			for (go = rbw->group->gobject.first; go; go = go->next) {
				if (go->ob && go->ob->rigidbody_object) {
					RigidBodyOb *rbo = go->ob->rigidbody_object;

					if (rbo->physics_object)
						RB_dworld_remove_body(rbw->physics_world, rbo->physics_object);
				}
			}
		}
		/* free dynamics world */
		RB_dworld_delete(rbw->physics_world);
	}
	if (rbw->objects)
		free(rbw->objects);

	/* free rigidbody world itself */
	MEM_freeN(rbw);
}

/* Free RigidBody settings and sim instances */
void BKE_rigidbody_free_object(Object *ob)
{
	RigidBodyOb *rbo = (ob) ? ob->rigidbody_object : NULL;

	/* sanity check */
	if (rbo == NULL)
		return;

	/* free physics references */
	if (rbo->physics_object) {
		RB_body_delete(rbo->physics_object);
		rbo->physics_object = NULL;
	}

	if (rbo->physics_shape) {
		RB_shape_delete(rbo->physics_shape);
		rbo->physics_shape = NULL;
	}

	/* free data itself */
	MEM_freeN(rbo);
	ob->rigidbody_object = NULL;
}

/* Copying Methods --------------------- */

/* These just copy the data, clearing out references to physics objects.
 * Anything that uses them MUST verify that the copied object will
 * be added to relevant groups later...
 */

RigidBodyOb *BKE_rigidbody_copy_object(Object *ob)
{
	RigidBodyOb *rboN = NULL;

	if (ob->rigidbody_object) {
		/* just duplicate the whole struct first (to catch all the settings) */
		rboN = MEM_dupallocN(ob->rigidbody_object);

		/* tag object as needing to be verified */
		rboN->flag |= RBO_FLAG_NEEDS_VALIDATE;

		/* clear out all the fields which need to be revalidated later */
		rboN->physics_object = NULL;
		rboN->physics_shape = NULL;
	}

	/* return new copy of settings */
	return rboN;
}

/* ************************************** */
/* Setup Utilities - Validate Sim Instances */

/* create collision shape of mesh - convex hull */
static rbCollisionShape *rigidbody_get_shape_convexhull_from_mesh(Object *ob, float margin, bool *can_embed)
{
	rbCollisionShape *shape = NULL;
	Mesh *me = NULL;

	if (ob->type == OB_MESH && ob->data) {
		me = ob->data;
	}
	else {
		printf("ERROR: cannot make Convex Hull collision shape for non-Mesh object\n");
	}

	if (me && me->totvert) {
		shape = RB_shape_new_convex_hull((float *)me->mvert, sizeof(MVert), me->totvert, margin, can_embed);
	}
	else {
		printf("ERROR: no vertices to define Convex Hull collision shape with\n");
	}

	return shape;
}

/* create collision shape of mesh - triangulated mesh
 * returns NULL if creation fails.
 */
static rbCollisionShape *rigidbody_get_shape_trimesh_from_mesh(Object *ob)
{
	rbCollisionShape *shape = NULL;

	if (ob->type == OB_MESH) {
		DerivedMesh *dm = CDDM_from_mesh(ob->data, ob);

		MVert *mvert;
		MFace *mface;
		int totvert;
		int totface;

		/* ensure mesh validity, then grab data */
		DM_ensure_tessface(dm);

		mvert   = (dm) ? dm->getVertArray(dm) : NULL;
		totvert = (dm) ? dm->getNumVerts(dm) : 0;
		mface   = (dm) ? dm->getTessFaceArray(dm) : NULL;
		totface = (dm) ? dm->getNumTessFaces(dm) : 0;

		/* sanity checking - potential case when no data will be present */
		if ((totvert == 0) || (totface == 0)) {
			printf("WARNING: no geometry data converted for Mesh Collision Shape (ob = %s)\n", ob->id.name + 2);
		}
		else {
			rbMeshData *mdata;
			int i;

			/* init mesh data for collision shape */
			mdata = RB_trimesh_data_new();

			/* loop over all faces, adding them as triangles to the collision shape
			 * (so for some faces, more than triangle will get added)
			 */
			for (i = 0; (i < totface) && (mface) && (mvert); i++, mface++) {
				/* add first triangle - verts 1,2,3 */
				{
					MVert *va = (IN_RANGE(mface->v1, 0, totvert)) ? (mvert + mface->v1) : (mvert);
					MVert *vb = (IN_RANGE(mface->v2, 0, totvert)) ? (mvert + mface->v2) : (mvert);
					MVert *vc = (IN_RANGE(mface->v3, 0, totvert)) ? (mvert + mface->v3) : (mvert);

					RB_trimesh_add_triangle(mdata, va->co, vb->co, vc->co);
				}

				/* add second triangle if needed - verts 1,3,4 */
				if (mface->v4) {
					MVert *va = (IN_RANGE(mface->v1, 0, totvert)) ? (mvert + mface->v1) : (mvert);
					MVert *vb = (IN_RANGE(mface->v3, 0, totvert)) ? (mvert + mface->v3) : (mvert);
					MVert *vc = (IN_RANGE(mface->v4, 0, totvert)) ? (mvert + mface->v4) : (mvert);

					RB_trimesh_add_triangle(mdata, va->co, vb->co, vc->co);
				}
			}

			/* construct collision shape
			 *
			 * These have been chosen to get better speed/accuracy tradeoffs with regards
			 * to limitations of each:
			 *    - BVH-Triangle Mesh: for passive objects only. Despite having greater
			 *                         speed/accuracy, they cannot be used for moving objects.
			 *    - GImpact Mesh:      for active objects. These are slower and less stable,
			 *                         but are more flexible for general usage.
			 */
			if (ob->rigidbody_object->type == RBO_TYPE_PASSIVE) {
				shape = RB_shape_new_trimesh(mdata);
			}
			else {
				shape = RB_shape_new_gimpact_mesh(mdata);
			}
		}

		/* cleanup temp data */
		if (dm) {
			dm->release(dm);
		}
	}
	else {
		printf("ERROR: cannot make Triangular Mesh collision shape for non-Mesh object\n");
	}

	return shape;
}

/* Create new physics sim collision shape for object and store it,
 * or remove the existing one first and replace...
 */
void BKE_rigidbody_validate_sim_shape(Object *ob, short rebuild)
{
	RigidBodyOb *rbo = ob->rigidbody_object;
	rbCollisionShape *new_shape = NULL;
	BoundBox *bb = NULL;
	float size[3] = {1.0f, 1.0f, 1.0f};
	float radius = 1.0f;
	float height = 1.0f;
	float capsule_height;
	float hull_margin = 0.0f;
	bool can_embed = true;

	/* sanity check */
	if (rbo == NULL)
		return;

	/* don't create a new shape if we already have one and don't want to rebuild it */
	if (rbo->physics_shape && !rebuild)
		return;

	/* if automatically determining dimensions, use the Object's boundbox
	 *	- assume that all quadrics are standing upright on local z-axis
	 *	- assume even distribution of mass around the Object's pivot
	 *	  (i.e. Object pivot is centralised in boundbox)
	 */
	// XXX: all dimensions are auto-determined now... later can add stored settings for this
	/* get object dimensions without scaling */
	bb = BKE_object_boundbox_get(ob);
	if (bb) {
		size[0] = (bb->vec[4][0] - bb->vec[0][0]);
		size[1] = (bb->vec[2][1] - bb->vec[0][1]);
		size[2] = (bb->vec[1][2] - bb->vec[0][2]);
	}
	mul_v3_fl(size, 0.5f);

	if (ELEM3(rbo->shape, RB_SHAPE_CAPSULE, RB_SHAPE_CYLINDER, RB_SHAPE_CONE)) {
		/* take radius as largest x/y dimension, and height as z-dimension */
		radius = MAX2(size[0], size[1]);
		height = size[2];
	}
	else if (rbo->shape == RB_SHAPE_SPHERE) {
		/* take radius to the the largest dimension to try and encompass everything */
		radius = MAX3(size[0], size[1], size[2]);
	}

	/* create new shape */
	switch (rbo->shape) {
		case RB_SHAPE_BOX:
			new_shape = RB_shape_new_box(size[0], size[1], size[2]);
			break;

		case RB_SHAPE_SPHERE:
			new_shape = RB_shape_new_sphere(radius);
			break;

		case RB_SHAPE_CAPSULE:
			capsule_height = (height - radius) * 2.0f;
			new_shape = RB_shape_new_capsule(radius, (capsule_height > 0.0f) ? capsule_height : 0.0f);
			break;
		case RB_SHAPE_CYLINDER:
			new_shape = RB_shape_new_cylinder(radius, height);
			break;
		case RB_SHAPE_CONE:
			new_shape = RB_shape_new_cone(radius, height * 2.0f);
			break;

		case RB_SHAPE_CONVEXH:
			/* try to emged collision margin */
			if (!(rbo->flag & RBO_FLAG_USE_MARGIN))
				hull_margin = 0.04f;
			new_shape = rigidbody_get_shape_convexhull_from_mesh(ob, hull_margin, &can_embed);
			if (!(rbo->flag & RBO_FLAG_USE_MARGIN))
				rbo->margin = (can_embed) ? 0.04f : 0.0f;  /* RB_TODO ideally we shouldn't directly change the margin here */
			break;
		case RB_SHAPE_TRIMESH:
			new_shape = rigidbody_get_shape_trimesh_from_mesh(ob);
			break;
	}
	/* assign new collision shape if creation was successful */
	if (new_shape) {
		if (rbo->physics_shape)
			RB_shape_delete(rbo->physics_shape);
		rbo->physics_shape = new_shape;
		RB_shape_set_margin(rbo->physics_shape, RBO_GET_MARGIN(rbo));
	}
}

/* --------------------- */

/* Create physics sim representation of object given RigidBody settings
 * < rebuild: even if an instance already exists, replace it
 */
void BKE_rigidbody_validate_sim_object(RigidBodyWorld *rbw, Object *ob, short rebuild)
{
	RigidBodyOb *rbo = (ob) ? ob->rigidbody_object : NULL;
	float loc[3];
	float rot[4];

	/* sanity checks:
	 *	- object doesn't have RigidBody info already: then why is it here?
	 */
	if (rbo == NULL)
		return;

	/* make sure collision shape exists */
	if (rbo->physics_shape == NULL || rebuild)
		BKE_rigidbody_validate_sim_shape(ob, true);

	if (rbo->physics_object) {
		if (rebuild == false)
			RB_dworld_remove_body(rbw->physics_world, rbo->physics_object);
	}
	if (!rbo->physics_object || rebuild) {
		/* remove rigid body if it already exists before creating a new one */
		if (rbo->physics_object) {
			RB_body_delete(rbo->physics_object);
		}

		mat4_to_loc_quat(loc, rot, ob->obmat);

		rbo->physics_object = RB_body_new(rbo->physics_shape, loc, rot);

		RB_body_set_friction(rbo->physics_object, rbo->friction);
		RB_body_set_restitution(rbo->physics_object, rbo->restitution);

		RB_body_set_damping(rbo->physics_object, rbo->lin_damping, rbo->ang_damping);
		RB_body_set_sleep_thresh(rbo->physics_object, rbo->lin_sleep_thresh, rbo->ang_sleep_thresh);
		RB_body_set_activation_state(rbo->physics_object, rbo->flag & RBO_FLAG_USE_DEACTIVATION);

		if (rbo->type == RBO_TYPE_PASSIVE || rbo->flag & RBO_FLAG_START_DEACTIVATED)
			RB_body_deactivate(rbo->physics_object);


		RB_body_set_linear_factor(rbo->physics_object,
								  (ob->protectflag & OB_LOCK_LOCX) == 0,
		                          (ob->protectflag & OB_LOCK_LOCY) == 0,
		                          (ob->protectflag & OB_LOCK_LOCZ) == 0);
		RB_body_set_angular_factor(rbo->physics_object,
		                           (ob->protectflag & OB_LOCK_ROTX) == 0,
		                           (ob->protectflag & OB_LOCK_ROTY) == 0,
		                           (ob->protectflag & OB_LOCK_ROTZ) == 0);

		RB_body_set_mass(rbo->physics_object, RBO_GET_MASS(rbo));
		RB_body_set_kinematic_state(rbo->physics_object, rbo->flag & RBO_FLAG_KINEMATIC || rbo->flag & RBO_FLAG_DISABLED);
	}

	if (rbw && rbw->physics_world)
		RB_dworld_add_body(rbw->physics_world, rbo->physics_object, rbo->col_groups);
}

/* --------------------- */

/* Create physics sim world given RigidBody world settings */
// NOTE: this does NOT update object references that the scene uses, in case those aren't ready yet!
void BKE_rigidbody_validate_sim_world(Scene *scene, RigidBodyWorld *rbw, short rebuild)
{
	/* sanity checks */
	if (rbw == NULL)
		return;

	/* create new sim world */
	if (rebuild || rbw->physics_world == NULL) {
		if (rbw->physics_world)
			RB_dworld_delete(rbw->physics_world);
		rbw->physics_world = RB_dworld_new(scene->physics_settings.gravity);
	}

	RB_dworld_set_solver_iterations(rbw->physics_world, rbw->num_solver_iterations);
	RB_dworld_set_split_impulse(rbw->physics_world, rbw->flag & RBW_FLAG_USE_SPLIT_IMPULSE);
}

/* ************************************** */
/* Setup Utilities - Create Settings Blocks */

/* Set up RigidBody world */
RigidBodyWorld *BKE_rigidbody_create_world(Scene *scene)
{
	/* try to get whatever RigidBody world that might be representing this already */
	RigidBodyWorld *rbw;

	/* sanity checks
	 *	- there must be a valid scene to add world to
	 *	- there mustn't be a sim world using this group already
	 */
	if (scene == NULL)
		return NULL;

	/* create a new sim world */
	rbw = MEM_callocN(sizeof(RigidBodyWorld), "RigidBodyWorld");

	/* set default settings */
	rbw->ltime = PSFRA;

	rbw->time_scale = 1.0f;

	rbw->steps_per_second = 60; /* Bullet default (60 Hz) */
	rbw->num_solver_iterations = 10; /* 10 is bullet default */

	/* return this sim world */
	return rbw;
}

/* Add rigid body settings to the specified object */
RigidBodyOb *BKE_rigidbody_create_object(Scene *scene, Object *ob, short type)
{
	RigidBodyOb *rbo;
	RigidBodyWorld *rbw = scene->rigidbody_world;

	/* sanity checks
	 *	- rigidbody world must exist
	 *	- object must exist
	 *	- cannot add rigid body if it already exists
	 */
	if (ob == NULL || (ob->rigidbody_object != NULL))
		return NULL;

	/* create new settings data, and link it up */
	rbo = MEM_callocN(sizeof(RigidBodyOb), "RigidBodyOb");

	/* set default settings */
	rbo->type = type;

	rbo->mass = 1.0f;

	rbo->friction = 0.5f; /* best when non-zero. 0.5 is Bullet default */
	rbo->restitution = 0.0f; /* best when zero. 0.0 is Bullet default */

	rbo->margin = 0.04f; /* 0.04 (in meters) is Bullet default */

	rbo->lin_sleep_thresh = 0.4f; /* 0.4 is half of Bullet default */
	rbo->ang_sleep_thresh = 0.5f; /* 0.5 is half of Bullet default */

	rbo->lin_damping = 0.04f; /* 0.04 is game engine default */
	rbo->ang_damping = 0.1f; /* 0.1 is game engine default */

	rbo->col_groups = 1;

	/* use triangle meshes for passive objects
	 * use convex hulls for active objects since dynamic triangle meshes are very unstable
	 */
	if (type == RBO_TYPE_ACTIVE)
		rbo->shape = RB_SHAPE_CONVEXH;
	else
		rbo->shape = RB_SHAPE_TRIMESH;

	/* set initial transform */
	mat4_to_loc_quat(rbo->pos, rbo->orn, ob->obmat);

	/* flag cache as outdated */
	BKE_rigidbody_cache_reset(rbw);

	/* return this object */
	return rbo;
}

/* ************************************** */
/* Utilities API */

/* Get RigidBody world for the given scene, creating one if needed
 * < scene: Scene to find active Rigid Body world for
 */
RigidBodyWorld *BKE_rigidbody_get_world(Scene *scene)
{
	/* sanity check */
	if (scene == NULL)
		return NULL;

	return scene->rigidbody_world;
}

void BKE_rigidbody_remove_object(Scene *scene, Object *ob)
{
	RigidBodyWorld *rbw = scene->rigidbody_world;
	RigidBodyOb *rbo = ob->rigidbody_object;
	GroupObject *go;
	int i;

	if (rbw) {
		/* remove from rigidbody world, free object won't do this */
		if (rbw->physics_world && rbo->physics_object)
			RB_dworld_remove_body(rbw->physics_world, rbo->physics_object);

		/* remove object from array */
		if (rbw && rbw->objects) {
			for (i = 0; i < rbw->numbodies; i++) {
				if (rbw->objects[i] == ob) {
					rbw->objects[i] = NULL;
					break;
				}
			}
		}
	}
	/* remove object's settings */
	BKE_rigidbody_free_object(ob);
	/* flag cache as outdated */
	BKE_rigidbody_cache_reset(rbw);
}


/* ************************************** */
/* Simulation Interface - Bullet */

/* Update object array and rigid body count so they're in sync with the rigid body group */
static void rigidbody_update_ob_array(RigidBodyWorld *rbw)
{
	GroupObject *go;
	int i, n;

	n = BLI_countlist(&rbw->group->gobject);

	if (rbw->numbodies != n) {
		rbw->numbodies = n;
		rbw->objects = realloc(rbw->objects, sizeof(Object *) * rbw->numbodies);
	}

	for (go = rbw->group->gobject.first, i = 0; go; go = go->next, i++) {
		Object *ob = go->ob;
		rbw->objects[i] = ob;
	}
}

static void rigidbody_update_sim_world(Scene *scene, RigidBodyWorld *rbw)
{
	float adj_gravity[3];

	/* adjust gravity to take effector weights into account */
	if (scene->physics_settings.flag & PHYS_GLOBAL_GRAVITY) {
		copy_v3_v3(adj_gravity, scene->physics_settings.gravity);
	}
	else {
		zero_v3(adj_gravity);
	}

	/* update gravity, since this RNA setting is not part of RigidBody settings */
	RB_dworld_set_gravity(rbw->physics_world, adj_gravity);

	/* update object array in case there are changes */
	rigidbody_update_ob_array(rbw);
}

static void rigidbody_update_sim_ob(Scene *scene, RigidBodyWorld *rbw, Object *ob, RigidBodyOb *rbo)
{
	float loc[3];
	float rot[4];
	float scale[3];

	/* only update if rigid body exists */
	if (rbo->physics_object == NULL)
		return;

	mat4_decompose(loc, rot, scale, ob->obmat);

	/* update scale for all objects */
	RB_body_set_scale(rbo->physics_object, scale);
	/* compensate for embedded convex hull collision margin */
	if (!(rbo->flag & RBO_FLAG_USE_MARGIN) && rbo->shape == RB_SHAPE_CONVEXH)
		RB_shape_set_margin(rbo->physics_shape, RBO_GET_MARGIN(rbo) * MIN3(scale[0], scale[1], scale[2]));

	/* update rigid body location and rotation for kinematic bodies */
	if (rbo->flag & RBO_FLAG_KINEMATIC) {
		RB_body_activate(rbo->physics_object);
		RB_body_set_loc_rot(rbo->physics_object, loc, rot);
	}
	/* NOTE: passive objects don't need to be updated since they don't move */

	/* NOTE: no other settings need to be explicitly updated here,
	 * since RNA setters take care of the rest :)
	 */
}

/* Updates and validates world, bodies and shapes.
 * < rebuild: rebuild entire simulation
 */
static void rigidbody_update_simulation(Scene *scene, RigidBodyWorld *rbw, int rebuild)
{
	GroupObject *go;

	/* update world */
	if (rebuild)
		BKE_rigidbody_validate_sim_world(scene, rbw, true);
	rigidbody_update_sim_world(scene, rbw);

	/* update objects */
	for (go = rbw->group->gobject.first; go; go = go->next) {
		Object *ob = go->ob;

		if (ob && ob->type == OB_MESH) {
			/* validate that we've got valid object set up here... */
			RigidBodyOb *rbo = ob->rigidbody_object;
			/* update transformation matrix of the object so we don't get a frame of lag for simple animations */
			BKE_object_where_is_calc(scene, ob);

			if (rbo == NULL) {
				/* Since this object is included in the sim group but doesn't have
				 * rigid body settings (perhaps it was added manually), add!
				 *	- assume object to be active? That is the default for newly added settings...
				 */
				ob->rigidbody_object = BKE_rigidbody_create_object(scene, ob, RBO_TYPE_ACTIVE);
				BKE_rigidbody_validate_sim_object(rbw, ob, true);

				rbo = ob->rigidbody_object;
			}
			else {
				/* perform simulation data updates as tagged */
				/* refresh object... */
				if (rebuild) {
					/* World has been rebuilt so rebuild object */
					BKE_rigidbody_validate_sim_object(rbw, ob, true);
				}
				else if (rbo->flag & RBO_FLAG_NEEDS_VALIDATE) {
					BKE_rigidbody_validate_sim_object(rbw, ob, false);
				}
				/* refresh shape... */
				if (rbo->flag & RBO_FLAG_NEEDS_RESHAPE) {
					/* mesh/shape data changed, so force shape refresh */
					BKE_rigidbody_validate_sim_shape(ob, true);
					/* now tell RB sim about it */
					// XXX: we assume that this can only get applied for active/passive shapes that will be included as rigidbodies
					RB_body_set_collision_shape(rbo->physics_object, rbo->physics_shape);
				}
				rbo->flag &= ~(RBO_FLAG_NEEDS_VALIDATE | RBO_FLAG_NEEDS_RESHAPE);
			}

			/* update simulation object... */
			rigidbody_update_sim_ob(scene, rbw, ob, rbo);
		}
	}
}

/* Sync rigid body and object transformations */
void BKE_rigidbody_sync_transforms(Scene *scene, Object *ob, float ctime)
{
// RB_TODO implement this
}

void BKE_rigidbody_cache_reset(RigidBodyWorld *rbw)
{
// RB_TODO implement this
}

/* ------------------ */

/* Run RigidBody simulation for the specified physics world */
void BKE_rigidbody_do_simulation(Scene *scene, float ctime)
{
// RB_TODO implement this
}
/* ************************************** */