/*
 * ***** 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.
 *
 * Original author: Benoit Bolsee
 * Contributor(s):
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/ikplugin/intern/iksolver_plugin.c
 *  \ingroup ikplugin
 */

#include "MEM_guardedalloc.h"

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

#include "BKE_armature.h"
#include "BKE_constraint.h"

#include "DNA_object_types.h"
#include "DNA_action_types.h"
#include "DNA_constraint_types.h"
#include "DNA_armature_types.h"

#include "IK_solver.h"
#include "iksolver_plugin.h"

#include <string.h> /* memcpy */

/* ********************** THE IK SOLVER ******************* */

/* allocates PoseTree, and links that to root bone/channel */
/* Note: detecting the IK chain is duplicate code... in drawarmature.c and in transform_conversions.c */
static void initialize_posetree(struct Object *UNUSED(ob), bPoseChannel *pchan_tip)
{
	bPoseChannel *curchan, *pchan_root = NULL, *chanlist[256], **oldchan;
	PoseTree *tree;
	PoseTarget *target;
	bConstraint *con;
	bKinematicConstraint *data;
	int a, t, segcount = 0, size, newsize, *oldparent, parent;

	/* find IK constraint, and validate it */
	for (con = pchan_tip->constraints.first; con; con = con->next) {
		if (con->type == CONSTRAINT_TYPE_KINEMATIC) {
			data = (bKinematicConstraint *)con->data;
			if (data->flag & CONSTRAINT_IK_AUTO) break;
			if (data->tar == NULL) continue;
			if (data->tar->type == OB_ARMATURE && data->subtarget[0] == 0) continue;
			if ((con->flag & (CONSTRAINT_DISABLE | CONSTRAINT_OFF)) == 0 && (con->enforce != 0.0f)) break;
		}
	}
	if (con == NULL) return;

	/* exclude tip from chain? */
	if (!(data->flag & CONSTRAINT_IK_TIP))
		pchan_tip = pchan_tip->parent;

	/* Find the chain's root & count the segments needed */
	for (curchan = pchan_tip; curchan; curchan = curchan->parent) {
		pchan_root = curchan;

		curchan->flag |= POSE_CHAIN;    // don't forget to clear this
		chanlist[segcount] = curchan;
		segcount++;

		if (segcount == data->rootbone || segcount > 255) break;  // 255 is weak
	}
	if (!segcount) return;

	/* setup the chain data */

	/* we make tree-IK, unless all existing targets are in this chain */
	for (tree = pchan_root->iktree.first; tree; tree = tree->next) {
		for (target = tree->targets.first; target; target = target->next) {
			curchan = tree->pchan[target->tip];
			if (curchan->flag & POSE_CHAIN)
				curchan->flag &= ~POSE_CHAIN;
			else
				break;
		}
		if (target) break;
	}

	/* create a target */
	target = MEM_callocN(sizeof(PoseTarget), "posetarget");
	target->con = con;
	pchan_tip->flag &= ~POSE_CHAIN;

	if (tree == NULL) {
		/* make new tree */
		tree = MEM_callocN(sizeof(PoseTree), "posetree");

		tree->type = CONSTRAINT_TYPE_KINEMATIC;

		tree->iterations = data->iterations;
		tree->totchannel = segcount;
		tree->stretch = (data->flag & CONSTRAINT_IK_STRETCH);

		tree->pchan = MEM_callocN(segcount * sizeof(void *), "ik tree pchan");
		tree->parent = MEM_callocN(segcount * sizeof(int), "ik tree parent");
		for (a = 0; a < segcount; a++) {
			tree->pchan[a] = chanlist[segcount - a - 1];
			tree->parent[a] = a - 1;
		}
		target->tip = segcount - 1;

		/* AND! link the tree to the root */
		BLI_addtail(&pchan_root->iktree, tree);
	}
	else {
		tree->iterations = MAX2(data->iterations, tree->iterations);
		tree->stretch = tree->stretch && !(data->flag & CONSTRAINT_IK_STRETCH);

		/* skip common pose channels and add remaining*/
		size = MIN2(segcount, tree->totchannel);
		a = t = 0;
		while (a < size && t < tree->totchannel) {
			/* locate first matching channel */
			for (; t < tree->totchannel && tree->pchan[t] != chanlist[segcount - a - 1]; t++) ;
			if (t >= tree->totchannel)
				break;
			for (; a < size && t < tree->totchannel && tree->pchan[t] == chanlist[segcount - a - 1]; a++, t++) ;
		}

		segcount = segcount - a;
		target->tip = tree->totchannel + segcount - 1;

		if (segcount > 0) {
			for (parent = a - 1; parent < tree->totchannel; parent++)
				if (tree->pchan[parent] == chanlist[segcount - 1]->parent)
					break;

			/* shouldn't happen, but could with dependency cycles */
			if (parent == tree->totchannel)
				parent = a - 1;

			/* resize array */
			newsize = tree->totchannel + segcount;
			oldchan = tree->pchan;
			oldparent = tree->parent;

			tree->pchan = MEM_callocN(newsize * sizeof(void *), "ik tree pchan");
			tree->parent = MEM_callocN(newsize * sizeof(int), "ik tree parent");
			memcpy(tree->pchan, oldchan, sizeof(void *) * tree->totchannel);
			memcpy(tree->parent, oldparent, sizeof(int) * tree->totchannel);
			MEM_freeN(oldchan);
			MEM_freeN(oldparent);

			/* add new pose channels at the end, in reverse order */
			for (a = 0; a < segcount; a++) {
				tree->pchan[tree->totchannel + a] = chanlist[segcount - a - 1];
				tree->parent[tree->totchannel + a] = tree->totchannel + a - 1;
			}
			tree->parent[tree->totchannel] = parent;

			tree->totchannel = newsize;
		}

		/* move tree to end of list, for correct evaluation order */
		BLI_remlink(&pchan_root->iktree, tree);
		BLI_addtail(&pchan_root->iktree, tree);
	}

	/* add target to the tree */
	BLI_addtail(&tree->targets, target);
	/* mark root channel having an IK tree */
	pchan_root->flag |= POSE_IKTREE;
}


/* transform from bone(b) to bone(b+1), store in chan_mat */
static void make_dmats(bPoseChannel *pchan)
{
	if (pchan->parent) {
		float iR_parmat[4][4];
		invert_m4_m4(iR_parmat, pchan->parent->pose_mat);
		mult_m4_m4m4(pchan->chan_mat, iR_parmat,  pchan->pose_mat); // delta mat
	}
	else copy_m4_m4(pchan->chan_mat, pchan->pose_mat);
}

/* applies IK matrix to pchan, IK is done separated */
/* formula: pose_mat(b) = pose_mat(b-1) * diffmat(b-1, b) * ik_mat(b) */
/* to make this work, the diffmats have to be precalculated! Stored in chan_mat */
static void where_is_ik_bone(bPoseChannel *pchan, float ik_mat[3][3])   // nr = to detect if this is first bone
{
	float vec[3], ikmat[4][4];

	copy_m4_m3(ikmat, ik_mat);

	if (pchan->parent)
		mul_serie_m4(pchan->pose_mat, pchan->parent->pose_mat, pchan->chan_mat, ikmat, NULL, NULL, NULL, NULL, NULL);
	else
		mult_m4_m4m4(pchan->pose_mat, pchan->chan_mat, ikmat);

	/* calculate head */
	copy_v3_v3(pchan->pose_head, pchan->pose_mat[3]);
	/* calculate tail */
	copy_v3_v3(vec, pchan->pose_mat[1]);
	mul_v3_fl(vec, pchan->bone->length);
	add_v3_v3v3(pchan->pose_tail, pchan->pose_head, vec);

	pchan->flag |= POSE_DONE;
}


/* called from within the core BKE_pose_where_is loop, all animsystems and constraints
 * were executed & assigned. Now as last we do an IK pass */
static void execute_posetree(struct Scene *scene, Object *ob, PoseTree *tree)
{
	float R_parmat[3][3], identity[3][3];
	float iR_parmat[3][3];
	float R_bonemat[3][3];
	float goalrot[3][3], goalpos[3];
	float rootmat[4][4], imat[4][4];
	float goal[4][4], goalinv[4][4];
	float irest_basis[3][3], full_basis[3][3];
	float end_pose[4][4], world_pose[4][4];
	float length, basis[3][3], rest_basis[3][3], start[3], *ikstretch = NULL;
	float resultinf = 0.0f;
	int a, flag, hasstretch = 0, resultblend = 0;
	bPoseChannel *pchan;
	IK_Segment *seg, *parent, **iktree, *iktarget;
	IK_Solver *solver;
	PoseTarget *target;
	bKinematicConstraint *data, *poleangledata = NULL;
	Bone *bone;

	if (tree->totchannel == 0)
		return;

	iktree = MEM_mallocN(sizeof(void *) * tree->totchannel, "ik tree");

	for (a = 0; a < tree->totchannel; a++) {
		pchan = tree->pchan[a];
		bone = pchan->bone;

		/* set DoF flag */
		flag = 0;
		if (!(pchan->ikflag & BONE_IK_NO_XDOF) && !(pchan->ikflag & BONE_IK_NO_XDOF_TEMP))
			flag |= IK_XDOF;
		if (!(pchan->ikflag & BONE_IK_NO_YDOF) && !(pchan->ikflag & BONE_IK_NO_YDOF_TEMP))
			flag |= IK_YDOF;
		if (!(pchan->ikflag & BONE_IK_NO_ZDOF) && !(pchan->ikflag & BONE_IK_NO_ZDOF_TEMP))
			flag |= IK_ZDOF;

		if (tree->stretch && (pchan->ikstretch > 0.0f)) {
			flag |= IK_TRANS_YDOF;
			hasstretch = 1;
		}

		seg = iktree[a] = IK_CreateSegment(flag);

		/* find parent */
		if (a == 0)
			parent = NULL;
		else
			parent = iktree[tree->parent[a]];

		IK_SetParent(seg, parent);

		/* get the matrix that transforms from prevbone into this bone */
		copy_m3_m4(R_bonemat, pchan->pose_mat);

		/* gather transformations for this IK segment */

		if (pchan->parent)
			copy_m3_m4(R_parmat, pchan->parent->pose_mat);
		else
			unit_m3(R_parmat);

		/* bone offset */
		if (pchan->parent && (a > 0))
			sub_v3_v3v3(start, pchan->pose_head, pchan->parent->pose_tail);
		else
			/* only root bone (a = 0) has no parent */
			start[0] = start[1] = start[2] = 0.0f;

		/* change length based on bone size */
		length = bone->length * len_v3(R_bonemat[1]);

		/* compute rest basis and its inverse */
		copy_m3_m3(rest_basis, bone->bone_mat);
		copy_m3_m3(irest_basis, bone->bone_mat);
		transpose_m3(irest_basis);

		/* compute basis with rest_basis removed */
		invert_m3_m3(iR_parmat, R_parmat);
		mul_m3_m3m3(full_basis, iR_parmat, R_bonemat);
		mul_m3_m3m3(basis, irest_basis, full_basis);

		/* basis must be pure rotation */
		normalize_m3(basis);

		/* transform offset into local bone space */
		normalize_m3(iR_parmat);
		mul_m3_v3(iR_parmat, start);

		IK_SetTransform(seg, start, rest_basis, basis, length);

		if (pchan->ikflag & BONE_IK_XLIMIT)
			IK_SetLimit(seg, IK_X, pchan->limitmin[0], pchan->limitmax[0]);
		if (pchan->ikflag & BONE_IK_YLIMIT)
			IK_SetLimit(seg, IK_Y, pchan->limitmin[1], pchan->limitmax[1]);
		if (pchan->ikflag & BONE_IK_ZLIMIT)
			IK_SetLimit(seg, IK_Z, pchan->limitmin[2], pchan->limitmax[2]);

		IK_SetStiffness(seg, IK_X, pchan->stiffness[0]);
		IK_SetStiffness(seg, IK_Y, pchan->stiffness[1]);
		IK_SetStiffness(seg, IK_Z, pchan->stiffness[2]);

		if (tree->stretch && (pchan->ikstretch > 0.0f)) {
			const float ikstretch = pchan->ikstretch * pchan->ikstretch;
			/* this function does its own clamping */
			IK_SetStiffness(seg, IK_TRANS_Y, 1.0f - ikstretch);
			IK_SetLimit(seg, IK_TRANS_Y, IK_STRETCH_STIFF_MIN, IK_STRETCH_STIFF_MAX);
		}
	}

	solver = IK_CreateSolver(iktree[0]);

	/* set solver goals */

	/* first set the goal inverse transform, assuming the root of tree was done ok! */
	pchan = tree->pchan[0];
	if (pchan->parent) {
		/* transform goal by parent mat, so this rotation is not part of the
		 * segment's basis. otherwise rotation limits do not work on the
		 * local transform of the segment itself. */
		copy_m4_m4(rootmat, pchan->parent->pose_mat);
		/* However, we do not want to get (i.e. reverse) parent's scale, as it generates [#31008]
		 * kind of nasty bugs... */
		normalize_m4(rootmat);
	}
	else
		unit_m4(rootmat);
	copy_v3_v3(rootmat[3], pchan->pose_head);

	mult_m4_m4m4(imat, ob->obmat, rootmat);
	invert_m4_m4(goalinv, imat);

	for (target = tree->targets.first; target; target = target->next) {
		float polepos[3];
		int poleconstrain = 0;

		data = (bKinematicConstraint *)target->con->data;

		/* 1.0=ctime, we pass on object for auto-ik (owner-type here is object, even though
		 * strictly speaking, it is a posechannel)
		 */
		BKE_get_constraint_target_matrix(scene, target->con, 0, CONSTRAINT_OBTYPE_OBJECT, ob, rootmat, 1.0);

		/* and set and transform goal */
		mult_m4_m4m4(goal, goalinv, rootmat);

		copy_v3_v3(goalpos, goal[3]);
		copy_m3_m4(goalrot, goal);
		normalize_m3(goalrot);

		/* same for pole vector target */
		if (data->poletar) {
			BKE_get_constraint_target_matrix(scene, target->con, 1, CONSTRAINT_OBTYPE_OBJECT, ob, rootmat, 1.0);

			if (data->flag & CONSTRAINT_IK_SETANGLE) {
				/* don't solve IK when we are setting the pole angle */
				break;
			}
			else {
				mult_m4_m4m4(goal, goalinv, rootmat);
				copy_v3_v3(polepos, goal[3]);
				poleconstrain = 1;

				/* for pole targets, we blend the result of the ik solver
				 * instead of the target position, otherwise we can't get
				 * a smooth transition */
				resultblend = 1;
				resultinf = target->con->enforce;

				if (data->flag & CONSTRAINT_IK_GETANGLE) {
					poleangledata = data;
					data->flag &= ~CONSTRAINT_IK_GETANGLE;
				}
			}
		}

		/* do we need blending? */
		if (!resultblend && target->con->enforce != 1.0f) {
			float q1[4], q2[4], q[4];
			float fac = target->con->enforce;
			float mfac = 1.0f - fac;

			pchan = tree->pchan[target->tip];

			/* end effector in world space */
			copy_m4_m4(end_pose, pchan->pose_mat);
			copy_v3_v3(end_pose[3], pchan->pose_tail);
			mul_serie_m4(world_pose, goalinv, ob->obmat, end_pose, NULL, NULL, NULL, NULL, NULL);

			/* blend position */
			goalpos[0] = fac * goalpos[0] + mfac * world_pose[3][0];
			goalpos[1] = fac * goalpos[1] + mfac * world_pose[3][1];
			goalpos[2] = fac * goalpos[2] + mfac * world_pose[3][2];

			/* blend rotation */
			mat3_to_quat(q1, goalrot);
			mat4_to_quat(q2, world_pose);
			interp_qt_qtqt(q, q1, q2, mfac);
			quat_to_mat3(goalrot, q);
		}

		iktarget = iktree[target->tip];

		if ((data->flag & CONSTRAINT_IK_POS) && data->weight != 0.0f) {
			if (poleconstrain)
				IK_SolverSetPoleVectorConstraint(solver, iktarget, goalpos,
				                                 polepos, data->poleangle, (poleangledata == data));
			IK_SolverAddGoal(solver, iktarget, goalpos, data->weight);
		}
		if ((data->flag & CONSTRAINT_IK_ROT) && (data->orientweight != 0.0f))
			if ((data->flag & CONSTRAINT_IK_AUTO) == 0)
				IK_SolverAddGoalOrientation(solver, iktarget, goalrot,
				                            data->orientweight);
	}

	/* solve */
	IK_Solve(solver, 0.0f, tree->iterations);

	if (poleangledata)
		poleangledata->poleangle = IK_SolverGetPoleAngle(solver);

	IK_FreeSolver(solver);

	/* gather basis changes */
	tree->basis_change = MEM_mallocN(sizeof(float[3][3]) * tree->totchannel, "ik basis change");
	if (hasstretch)
		ikstretch = MEM_mallocN(sizeof(float) * tree->totchannel, "ik stretch");

	for (a = 0; a < tree->totchannel; a++) {
		IK_GetBasisChange(iktree[a], tree->basis_change[a]);

		if (hasstretch) {
			/* have to compensate for scaling received from parent */
			float parentstretch, stretch;

			pchan = tree->pchan[a];
			parentstretch = (tree->parent[a] >= 0) ? ikstretch[tree->parent[a]] : 1.0f;

			if (tree->stretch && (pchan->ikstretch > 0.0f)) {
				float trans[3], length;

				IK_GetTranslationChange(iktree[a], trans);
				length = pchan->bone->length * len_v3(pchan->pose_mat[1]);

				ikstretch[a] = (length == 0.0f) ? 1.0f : (trans[1] + length) / length;
			}
			else
				ikstretch[a] = 1.0;

			stretch = (parentstretch == 0.0f) ? 1.0f : ikstretch[a] / parentstretch;

			mul_v3_fl(tree->basis_change[a][0], stretch);
			mul_v3_fl(tree->basis_change[a][1], stretch);
			mul_v3_fl(tree->basis_change[a][2], stretch);
		}

		if (resultblend && resultinf != 1.0f) {
			unit_m3(identity);
			blend_m3_m3m3(tree->basis_change[a], identity,
			              tree->basis_change[a], resultinf);
		}

		IK_FreeSegment(iktree[a]);
	}

	MEM_freeN(iktree);
	if (ikstretch) MEM_freeN(ikstretch);
}

static void free_posetree(PoseTree *tree)
{
	BLI_freelistN(&tree->targets);
	if (tree->pchan) MEM_freeN(tree->pchan);
	if (tree->parent) MEM_freeN(tree->parent);
	if (tree->basis_change) MEM_freeN(tree->basis_change);
	MEM_freeN(tree);
}

///----------------------------------------
/// Plugin API for legacy iksolver

void iksolver_initialize_tree(struct Scene *UNUSED(scene), struct Object *ob, float UNUSED(ctime))
{
	bPoseChannel *pchan;

	for (pchan = ob->pose->chanbase.first; pchan; pchan = pchan->next) {
		if (pchan->constflag & PCHAN_HAS_IK) // flag is set on editing constraints
			initialize_posetree(ob, pchan);  // will attach it to root!
	}
	ob->pose->flag &= ~POSE_WAS_REBUILT;
}

void iksolver_execute_tree(struct Scene *scene, struct Object *ob,  struct bPoseChannel *pchan, float ctime)
{
	while (pchan->iktree.first) {
		PoseTree *tree = pchan->iktree.first;
		int a;

		/* stop on the first tree that isn't a standard IK chain */
		if (tree->type != CONSTRAINT_TYPE_KINEMATIC)
			return;

		/* 4. walk over the tree for regular solving */
		for (a = 0; a < tree->totchannel; a++) {
			if (!(tree->pchan[a]->flag & POSE_DONE))    // successive trees can set the flag
				BKE_pose_where_is_bone(scene, ob, tree->pchan[a], ctime, 1);
			/* tell blender that this channel was controlled by IK, it's cleared on each BKE_pose_where_is() */
			tree->pchan[a]->flag |= POSE_CHAIN;
		}
		/* 5. execute the IK solver */
		execute_posetree(scene, ob, tree);

		/* 6. apply the differences to the channels,
		 *    we need to calculate the original differences first */
		for (a = 0; a < tree->totchannel; a++) {
			make_dmats(tree->pchan[a]);
		}

		for (a = 0; a < tree->totchannel; a++) {
			/* sets POSE_DONE */
			where_is_ik_bone(tree->pchan[a], tree->basis_change[a]);
		}

		/* 7. and free */
		BLI_remlink(&pchan->iktree, tree);
		free_posetree(tree);
	}
}

