/**
 * @file llgltfasset.h
 * @brief LL GLTF Implementation
 *
 * $LicenseInfo:firstyear=2024&license=viewergpl$
 *
 * Copyright (c) 2024, Linden Research, Inc.
 *
 * Second Life Viewer Source Code
 * The source code in this file ("Source Code") is provided by Linden Lab
 * to you under the terms of the GNU General Public License, version 2.0
 * ("GPL"), unless you have obtained a separate licensing agreement
 * ("Other License"), formally executed by you and Linden Lab.  Terms of
 * the GPL can be found in doc/GPL-license.txt in this distribution, or
 * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
 *
 * There are special exceptions to the terms and conditions of the GPL as
 * it is applied to this Source Code. View the full text of the exception
 * in the file doc/FLOSS-exception.txt in this software distribution, or
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 */

#ifndef LL_LLGLTFASSET_H
#define LL_LLGLTFASSET_H

// *TODO: get rid of this (again) !  HB
#include "glh_linear.h"

#include "llgltfaccessor.h"
#include "llgltfanimation.h"
#include "llgltfmaterial.h"
#include "llgltfprimitive.h"

// Saves from including "tinygltf/tiny_gltf.h" here. HB
namespace tinygltf
{
	class Model;
	class Node;
	struct Image;
	struct Material;
	struct Mesh;
	struct Sampler;
	struct Scene;
	struct Skin;
	struct Texture;
}

namespace LLGLTF
{
	class Asset;

	class Material
	{
	public:
		const Material& operator=(const tinygltf::Material& src);

		void allocateGLResources(Asset& asset);

	public:
		// Use LLFetchedGLTFMaterial for now, but eventually we will want to
		// use a more flexible GLTF material implementation instead of the
		// fixed packing version we use for sharable GLTF material assets.
		// Note: to avoid importing newview structures and keep this module
		// inside a separate llgltf library, I use a LLGLTFMaterial pointer
		// (i.e. a pointer of the parent class type) one, and instead of
		// calling two methods specific to LLFetchedGLTFMaterial (new() and
		// bind()), I use two exported wrapper functions implemented in
		// llfetchedgltfmaterial.cpp. HB
		LLPointer<LLGLTFMaterial>	mMaterial;
		std::string					mName;
	};

	// Note 16-byte aligned because we use a vector of Primitive. HB
	class alignas(16) Mesh
	{
	public:
		LL_ALIGNED16_NEW_DELETE

		const Mesh& operator=(const tinygltf::Mesh& src);

		bool allocateGLResources(Asset& asset);

	public:
		// Aligned member first...
		std::vector<Primitive>	mPrimitives;
		// ... then the rest.
		std::vector<F64>		mWeights;
		std::string				mName;
	};

	// Note 16-byte aligned because we use LLMatrix4a member variables. HB
	class alignas(16) Node
	{
	public:
		LL_ALIGNED16_NEW_DELETE

		Node();

		const Node& operator=(const tinygltf::Node& src);

		// Sets mRenderMatrix to a transform that can be used for the current
		// render pass. 'modelview' is the parent's render matrix.
		void updateRenderTransforms(Asset& asset, const LLMatrix4a& modelview);

		// Updates mAssetMatrix and mAssetMatrixInv
		void updateTransforms(Asset& asset, const LLMatrix4a& parent_matrix);

		// Ensures mMatrix is valid; if mMatrixValid is false and mTRSValid is
		// true, will update mMatrix to match Translation/Rotation/Scale
		void makeMatrixValid();

		// Ensures Translation/Rotation/Scale are valid; if mTRSValid is false
		// and mMatrixValid is true, will update Translation/Rotation/Scale to
		// match mMatrix.
		void makeTRSValid();

		// Sets rotation of this node
		// SIDE EFFECT: invalidates mMatrix
		void setRotation(const glh::quaternionf& rotation);

		// Sets translation of this node
		// SIDE EFFECT: invalidates mMatrix
		void setTranslation(const glh::vec3f& translation);

		// Sets scale of this node
		// SIDE EFFECT: invalidates mMatrix
		void setScale(const glh::vec3f& scale);

	public:
		// Aligned members first...
		LLMatrix4a			mMatrix;			// Local transform
		LLMatrix4a			mRenderMatrix;		// Transform for rendering
		LLMatrix4a			mAssetMatrix;		// Local to asset space transf.
		LLMatrix4a			mAssetMatrixInv;	// Asset to local space transf.

		// ... then the rest.
		glh::quaternionf	mRotation;
		glh::vec3f			mTranslation;
		glh::vec3f			mScale;

		std::string			mName;

		std::vector<S32>	mChildren;
		S32					mParent;
		S32					mMesh;
		S32					mSkin;

		// If true, mMatrix is valid and up to date
		bool				mMatrixValid;

		// If true, translation/rotation/scale are valid and up to date
		bool				mTRSValid;

		bool				mNeedsApplyMatrix;
	};

	class Skin
	{
	public:
		Skin();

		void allocateGLResources(Asset& asset);
		void uploadMatrixPalette(Asset& asset, Node& node);

		const Skin& operator=(const tinygltf::Skin& src);

	public:
		std::string					mName;
		std::vector<S32>			mJoints;
		std::vector<glh::matrix4f>	mInverseBindMatricesData;
		S32							mInverseBindMatrices;
		S32							mSkeleton;
	};

	class Scene
	{
	public:
		const Scene& operator=(const tinygltf::Scene& src);

		void updateTransforms(Asset& asset);
		void updateRenderTransforms(Asset& asset, const LLMatrix4a& modelview);

	public:
		std::string			mName;
		std::vector<S32>	mNodes;
	};

	class Texture
	{
	public:
		Texture();
		
		const Texture& operator=(const tinygltf::Texture& src);

	public:
		std::string	mName;
		S32			mSampler;
		S32			mSource;
	};

	class Sampler
	{
	public:
		const Sampler& operator=(const tinygltf::Sampler& src);

	public:
		std::string	mName;
		S32			mMagFilter;
		S32			mMinFilter;
		S32			mWrapS;
		S32			mWrapT;
	};

	class Image
	{
	public:
		const Image& operator=(const tinygltf::Image& src);

		LL_INLINE void allocateGLResources()	{}

	public:
		std::string mName;
		std::string mUri;
		std::string mMimeType;
		std::vector<U8> mData;
		S32 mWidth;
		S32 mHeight;
		S32 mComponent;
		S32 mBits;
	};

	// C++ representation of a GLTF Asset
	// Note 16-byte aligned because we use a vectors of Node and Mesh. HB
	class alignas(16) Asset : public LLRefCount
	{
	public:
		LL_ALIGNED16_NEW_DELETE

		Asset();

		// Prepares the asset for rendering.
		// Returns true on success, or false on failure (at which point this
		// asset must be destroyed and never used). HB
		bool allocateGLResources(const std::string& filename,
								 const tinygltf::Model& model);

		// Called periodically (typically once per frame). Any ongoing work
		// (such as animations) should be handled here NOT guaranteed to be
		// called every frame. MAY be called more than once per frame. Upon
		// return, all Node Matrix transforms should be up to date.
		void update();

		// Updates asset-to-node and node-to-asset transforms
		void updateTransforms();

		// Updates node render transforms
		void updateRenderTransforms(const LLMatrix4a& modelview);

		void render(bool opaque, bool rigged = false);
		void renderOpaque();
		void renderTransparent();

		// Return the index of the node that the line segment intersects with,
		// or -1 if no hit input and output values must be in this asset's
		// local coordinate frame
		S32 lineSegmentIntersect(const LLVector4a& start,
								 const LLVector4a& end,
								 LLVector4a* intersectp = NULL,
								 LLVector2* tcoordp = NULL,
								 LLVector4a* normp = NULL,
								 LLVector4a* tangentp = NULL,
								 S32* prim_hitp = NULL);

		const Asset& operator=(const tinygltf::Model& src);

	public:
		// Aligned members first...
		std::vector<Node>		mNodes;
		std::vector<Mesh>		mMeshes;
		// ... then the rest.
		std::vector<Scene>		mScenes;
		std::vector<Material>	mMaterials;
		std::vector<Buffer>		mBuffers;
		std::vector<BufferView>	mBufferViews;
		std::vector<Texture>	mTextures;
		std::vector<Sampler>	mSamplers;
		std::vector<Image>		mImages;
		std::vector<Accessor>	mAccessors;
		std::vector<Animation>	mAnimations;
		std::vector<Skin>		mSkins;

		// The last time update() was called according to gFrameTimeSeconds
		F32 mLastUpdateTime;
	};
}

#endif	// LL_LLGLTFASSET_H