// Copyright (C) 2009-2021, Panagiotis Christopoulos Charitos and contributors.
// All rights reserved.
// Code licensed under the BSD License.
// http://www.anki3d.org/LICENSE

#include <AnKi/Scene/Components/SkinComponent.h>
#include <AnKi/Scene/SceneNode.h>
#include <AnKi/Scene/SceneGraph.h>
#include <AnKi/Resource/SkeletonResource.h>
#include <AnKi/Resource/AnimationResource.h>
#include <AnKi/Resource/ResourceManager.h>
#include <AnKi/Util/BitSet.h>

namespace anki {

ANKI_SCENE_COMPONENT_STATICS(SkinComponent)

SkinComponent::SkinComponent(SceneNode* node)
	: SceneComponent(node, getStaticClassId())
	, m_node(node)
{
}

SkinComponent::~SkinComponent()
{
	m_boneTrfs[0].destroy(m_node->getAllocator());
	m_boneTrfs[1].destroy(m_node->getAllocator());
	m_animationTrfs.destroy(m_node->getAllocator());
}

Error SkinComponent::loadSkeletonResource(CString fname)
{
	ANKI_CHECK(m_node->getSceneGraph().getResourceManager().loadResource(fname, m_skeleton));

	m_boneTrfs[0].destroy(m_node->getAllocator());
	m_boneTrfs[1].destroy(m_node->getAllocator());
	m_animationTrfs.destroy(m_node->getAllocator());

	m_boneTrfs[0].create(m_node->getAllocator(), m_skeleton->getBones().getSize(), Mat4::getIdentity());
	m_boneTrfs[1].create(m_node->getAllocator(), m_skeleton->getBones().getSize(), Mat4::getIdentity());
	m_animationTrfs.create(m_node->getAllocator(), m_skeleton->getBones().getSize(),
						   {Vec3(0.0f), Quat::getIdentity(), 1.0f});

	return Error::NONE;
}

void SkinComponent::playAnimation(U32 track, AnimationResourcePtr anim, const AnimationPlayInfo& info)
{
	const Second animDuration = anim->getDuration();

	m_tracks[track].m_anim = anim;
	m_tracks[track].m_absoluteStartTime = m_absoluteTime + info.m_startTime;
	m_tracks[track].m_relativeTimePassed = 0.0;
	if(info.m_repeatTimes > 0.0)
	{
		m_tracks[track].m_blendInTime = min(animDuration * info.m_repeatTimes, info.m_blendInTime);
		m_tracks[track].m_blendOutTime = min(animDuration * info.m_repeatTimes, info.m_blendOutTime);
	}
	else
	{
		m_tracks[track].m_blendInTime = info.m_blendInTime;
		m_tracks[track].m_blendOutTime = 0.0; // Irrelevant
	}
	m_tracks[track].m_repeatTimes = info.m_repeatTimes;
}

Error SkinComponent::update(SceneNode& node, Second prevTime, Second crntTime, Bool& updated)
{
	ANKI_ASSERT(&node == m_node);

	updated = false;
	if(!m_skeleton.isCreated())
	{
		return Error::NONE;
	}

	const Second dt = crntTime - prevTime;

	Vec4 minExtend(MAX_F32, MAX_F32, MAX_F32, 0.0f);
	Vec4 maxExtend(MIN_F32, MIN_F32, MIN_F32, 0.0f);

	BitSet<128> bonesAnimated(false);

	for(Track& track : m_tracks)
	{
		if(!track.m_anim.isCreated())
		{
			continue;
		}

		if(track.m_absoluteStartTime > m_absoluteTime)
		{
			// Hasn't started yet
			continue;
		}

		const Second clipDuration = track.m_anim->getDuration();
		const Second animationDuration = track.m_repeatTimes * clipDuration;

		if(track.m_repeatTimes > 0.0 && track.m_relativeTimePassed > animationDuration)
		{
			// Animation finished
			continue;
		}

		updated = true;

		const Second animTime = track.m_relativeTimePassed;
		track.m_relativeTimePassed += dt;

		// Iterate the animation channels and interpolate
		for(U32 i = 0; i < track.m_anim->getChannels().getSize(); ++i)
		{
			const AnimationChannel& channel = track.m_anim->getChannels()[i];
			const Bone* bone = m_skeleton->tryFindBone(channel.m_name.toCString());
			if(!bone)
			{
				ANKI_SCENE_LOGW("Animation is referencing unknown bone \"%s\"", &channel.m_name[0]);
				continue;
			}
			const U32 boneIdx = bone->getIndex();

			// Interpolate
			Vec3 position;
			Quat rotation;
			F32 scale;
			track.m_anim->interpolate(i, animTime, position, rotation, scale);

			// Blend with previous track
			if(bonesAnimated.get(boneIdx) && (track.m_blendInTime > 0.0 || track.m_blendOutTime > 0.0))
			{
				F32 blendInFactor;
				if(track.m_blendInTime > 0.0)
				{
					blendInFactor = min(1.0f, F32(animTime / track.m_blendInTime));
				}
				else
				{
					blendInFactor = 1.0f;
				}

				F32 blendOutFactor;
				if(track.m_blendOutTime > 0.0)
				{
					blendOutFactor = min(1.0f, F32((animationDuration - animTime) / track.m_blendOutTime));
				}
				else
				{
					blendOutFactor = 1.0f;
				}

				const F32 factor = blendInFactor * blendOutFactor;

				if(factor < 1.0f)
				{
					const Trf& prevTrf = m_animationTrfs[boneIdx];

					position = linearInterpolate(prevTrf.m_translation, position, factor);
					rotation = prevTrf.m_rotation.slerp(rotation, factor);
					scale = linearInterpolate(prevTrf.m_scale, scale, factor);
				}
			}

			// Store
			bonesAnimated.set(boneIdx);
			m_animationTrfs[boneIdx] = {position, rotation, scale};
		}
	}

	// Always update the 1st time
	updated = updated || (m_absoluteTime == 0.0);

	if(updated)
	{
		m_prevBoneTrfs = m_crntBoneTrfs;
		m_crntBoneTrfs = m_crntBoneTrfs ^ 1;

		// Walk the bone hierarchy to add additional transforms
		visitBones(m_skeleton->getRootBone(), Mat4::getIdentity(), bonesAnimated, minExtend, maxExtend);

		const Vec4 E(EPSILON, EPSILON, EPSILON, 0.0f);
		m_boneBoundingVolume.setMin(minExtend - E);
		m_boneBoundingVolume.setMax(maxExtend + E);
	}
	else
	{
		m_prevBoneTrfs = m_crntBoneTrfs;
	}

	m_absoluteTime += dt;

	return Error::NONE;
}

void SkinComponent::visitBones(const Bone& bone, const Mat4& parentTrf, const BitSet<128>& bonesAnimated,
							   Vec4& minExtend, Vec4& maxExtend)
{
	Mat4 outMat;

	if(bonesAnimated.get(bone.getIndex()))
	{
		const Trf& t = m_animationTrfs[bone.getIndex()];
		outMat = parentTrf * Mat4(t.m_translation.xyz1(), Mat3(t.m_rotation), t.m_scale);
	}
	else
	{
		outMat = parentTrf * bone.getTransform();
	}

	m_boneTrfs[m_crntBoneTrfs][bone.getIndex()] = outMat * bone.getVertexTransform();

	// Update volume
	const Vec4 bonePos = outMat * Vec4(0.0f, 0.0f, 0.0f, 1.0f);
	minExtend = minExtend.min(bonePos.xyz0());
	maxExtend = maxExtend.max(bonePos.xyz0());

	for(const Bone* child : bone.getChildren())
	{
		visitBones(*child, outMat, bonesAnimated, minExtend, maxExtend);
	}
}

} // end namespace anki