/*
	This file is part of Daydream Engine.
	Copyright 2014 Adam Byléhn, Tobias Dahl, Simon Holmberg, Viktor Ljung
	
	Daydream Engine is free software: you can redistribute it and/or modify
	it under the terms of the GNU Lesser General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.
	
	Daydream Engine 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 Lesser General Public License for more details.
	
	You should have received a copy of the GNU Lesser General Public License
	along with Daydream Engine.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "PrecompiledHeader.h"
#include "Rendering/Skeleton.h"

int dd::Skeleton::CreateBone(int ID, int parentID, std::string name, glm::mat4 offsetMatrix)
{
	if (m_BonesByName.find(name) != m_BonesByName.end()) {
		return m_BonesByName.at(name)->ID;
	} else {
		Bone* bone;

		if (parentID == -1) {
			bone = new Bone(ID, nullptr, name, offsetMatrix);
			RootBone = bone;
		} else {
			Bone* parent = Bones[parentID];
			bone = new Bone(ID, parent, name, offsetMatrix);
			parent->Children.push_back(bone);
		}
		
		Bones[ID] = bone;
		m_BonesByName[name] = bone;
		return ID;
	}
}

dd::Skeleton::~Skeleton()
{
	for (auto &kv : Bones) {
		delete kv.second;
	}
}

const dd::Skeleton::Animation* dd::Skeleton::GetAnimation(std::string name)
{
	auto it = Animations.find(name);
	if (it != Animations.end()) {
		return const_cast<const Animation*>(&it->second);
	} else {
		return nullptr;
	}
}

std::vector<glm::mat4> dd::Skeleton::GetFrameBones(const Animation& animation, double time, bool noRootMotion /*= false*/)
{
	// HACK: Animation wrap-around
	while (time < 0)
		time += animation.Duration;
	while (time > animation.Duration)
		time -= animation.Duration;

	int currentKeyframeIndex = GetKeyframe(animation, time);

	const Animation::Keyframe& currentFrame = animation.Keyframes[currentKeyframeIndex];
	const Animation::Keyframe&	nextFrame = animation.Keyframes[(currentKeyframeIndex + 1) % animation.Keyframes.size()];
	float alpha = (time - currentFrame.Time) / (nextFrame.Time - currentFrame.Time);

	//auto animationFrame = Animations[""].Keyframes[frame];
	std::map<int, glm::mat4> frameBones;
	AccumulateBoneTransforms(noRootMotion, currentFrame, nextFrame, alpha, frameBones, RootBone, glm::mat4(1));

	std::vector<glm::mat4> finalMatrices;
	for (auto &kv : frameBones) {
		finalMatrices.push_back(kv.second);
	}
	return finalMatrices;
}

void dd::Skeleton::AccumulateBoneTransforms(bool noRootMotion, const Animation::Keyframe &currentFrame, const Animation::Keyframe &nextFrame, float progress, std::map<int, glm::mat4> &boneMatrices, const Bone* bone, glm::mat4 parentMatrix)
{
	glm::mat4 boneMatrix;

	if (currentFrame.BoneProperties.find(bone->ID) != currentFrame.BoneProperties.end() || nextFrame.BoneProperties.find(bone->ID) != nextFrame.BoneProperties.end()) {
		Animation::Keyframe::BoneProperty currentBoneProperty = currentFrame.BoneProperties.at(bone->ID);
		Animation::Keyframe::BoneProperty nextBoneProperty = nextFrame.BoneProperties.at(bone->ID);

		glm::vec3 positionInterp = currentBoneProperty.Position * (1.f - progress) + nextBoneProperty.Position * progress;
		glm::quat rotationInterp = glm::slerp(currentBoneProperty.Rotation, nextBoneProperty.Rotation, progress);
		glm::vec3 scaleInterp = currentBoneProperty.Scale * (1.f - progress) + nextBoneProperty.Scale * progress;

		// Flag for no root motion
		if (bone == RootBone && noRootMotion) {
			positionInterp.x = 0;
			positionInterp.z = 0;
		}

		boneMatrix = parentMatrix * (glm::translate(positionInterp) * glm::toMat4(rotationInterp) * glm::scale(scaleInterp));
		boneMatrices[bone->ID] = boneMatrix * bone->OffsetMatrix;
	} else {
		boneMatrix = parentMatrix * bone->Parent->OffsetMatrix; // * glm::inverse(bone->OffsetMatrix);
		boneMatrices[bone->ID] = boneMatrix; // * bone->OffsetMatrix;
	}

	for (auto &child : bone->Children) {
		std::string name = child->Name;
		AccumulateBoneTransforms(noRootMotion, currentFrame, nextFrame, progress, boneMatrices, child, boneMatrix);
	}
}

int dd::Skeleton::GetBoneID(std::string name)
{
	if (m_BonesByName.find(name) == m_BonesByName.end()) {
		return -1;
	} else {
		return m_BonesByName.at(name)->ID;
	}
}

void dd::Skeleton::PrintSkeleton()
{
	if (LOG_LEVEL < LOG_LEVEL_DEBUG) {
		return;
	}
	PrintSkeleton(RootBone, 0);
}

void dd::Skeleton::PrintSkeleton(const Bone* bone, int depthCount)
{
	std::stringstream ss;
	ss << std::string(depthCount, ' ');
	ss << bone->ID << ": " << bone->Name;
	std::cout << ss.str() << std::endl;
	
	depthCount++;

	for (auto &child : bone->Children) {
		PrintSkeleton(child, depthCount);
	}
}

int dd::Skeleton::GetKeyframe(const Animation& animation, double time)
{
	if (time < 0)
		time = 0;
	if (time >= animation.Duration)
		return animation.Keyframes.size() - 1;

	for (int keyframe = 0; keyframe < animation.Keyframes.size(); ++keyframe) {
		if (animation.Keyframes[keyframe].Time > time)
			return (keyframe - 1) % animation.Keyframes.size();
	}

	return 0;
}