// Copyright (C) 2024 Jérôme "SirLynix" Leclercq (lynix680@gmail.com)
// This file is part of the "Nazara Engine - Core module"
// For conditions of distribution and use, see copyright notice in Config.hpp

#pragma once

#ifndef NAZARA_CORE_MESH_HPP
#define NAZARA_CORE_MESH_HPP

#include <NazaraUtils/Prerequisites.hpp>
#include <Nazara/Core/Config.hpp>
#include <Nazara/Core/Enums.hpp>
#include <Nazara/Core/ObjectLibrary.hpp>
#include <Nazara/Core/Resource.hpp>
#include <Nazara/Core/ResourceLoader.hpp>
#include <Nazara/Core/ResourceManager.hpp>
#include <Nazara/Core/ResourceParameters.hpp>
#include <Nazara/Core/ResourceSaver.hpp>
#include <Nazara/Core/Skeleton.hpp>
#include <Nazara/Core/SoftwareBuffer.hpp>
#include <Nazara/Core/SubMesh.hpp>
#include <Nazara/Core/VertexDeclaration.hpp>
#include <Nazara/Core/VertexStruct.hpp>
#include <Nazara/Math/Box.hpp>
#include <unordered_map>
#include <vector>

namespace Nz
{
	struct NAZARA_CORE_API MeshParams : ResourceParameters
	{
		// How buffer will be allocated (by default in RAM)
		BufferFactory bufferFactory = &SoftwareBufferFactory;

		// Buffer usage flags used to build the index buffers
		BufferUsageFlags indexBufferFlags = BufferUsage::DirectMapping | BufferUsage::Read | BufferUsage::Write;

		// Buffer usage flags used to build the vertex buffers
		BufferUsageFlags vertexBufferFlags = BufferUsage::DirectMapping | BufferUsage::Read | BufferUsage::Write;

		// Transform vertices and joints by these transformations
		Vector3f vertexOffset = Vector3f::Zero();

		Quaternionf vertexRotation = Quaternionf::Identity();

		Vector3f vertexScale = Vector3f::Unit();

		// Offset to apply on the texture coordinates (not scaled)
		Vector2f texCoordOffset = {0.f, 0.f};

		// Scale to apply on the texture coordinates
		Vector2f texCoordScale  = {1.f, 1.f};

		// If true, will load an animated version of the model if possible
		bool animated = true;

		// If true, will center the mesh vertices around the origin
		bool center = false;

		// Optimize the index buffers after loading, improve cache locality (and thus rendering speed) but increase loading time.
		#ifndef NAZARA_DEBUG
		bool optimizeIndexBuffers = true;
		#else
		bool optimizeIndexBuffers = false;
		#endif

		/* The declaration must have a Vector3f position component enabled
		 * If the declaration has a Vector2f UV component enabled, UV are generated
		 * If the declaration has a Vector3f Normals component enabled, Normals are generated.
		 * If the declaration has a Vector3f Tangents component enabled, Tangents are generated.
		 */
		std::shared_ptr<VertexDeclaration> vertexDeclaration = VertexDeclaration::Get(VertexLayout::XYZ_Normal_UV_Tangent);

		bool IsValid() const;
	};

	class Mesh;
	struct Primitive;
	class PrimitiveList;
	class StaticMesh;
	class SubMesh;

	using MeshVertex = VertexStruct_XYZ_Normal_UV_Tangent;
	using SkeletalMeshVertex = VertexStruct_XYZ_Normal_UV_Tangent_Skinning;

	using MeshLibrary = ObjectLibrary<Mesh>;
	using MeshLoader = ResourceLoader<Mesh, MeshParams>;
	using MeshManager = ResourceManager<Mesh, MeshParams>;
	using MeshSaver = ResourceSaver<Mesh, MeshParams>;

	struct MeshImpl;

	class NAZARA_CORE_API Mesh : public Resource
	{
		public:
			using Params = MeshParams;

			inline Mesh();
			Mesh(const Mesh&) = delete;
			Mesh(Mesh&&) = delete;
			~Mesh() = default;

			void AddSubMesh(std::shared_ptr<SubMesh> subMesh);
			void AddSubMesh(std::string identifier, std::shared_ptr<SubMesh> subMesh);

			std::shared_ptr<SubMesh> BuildSubMesh(const Primitive& primitive, const MeshParams& params = MeshParams());
			void BuildSubMeshes(const PrimitiveList& primitiveList, const MeshParams& params = MeshParams());

			bool CreateSkeletal(std::size_t jointCount);
			bool CreateStatic();
			void Destroy();

			void GenerateNormals();
			void GenerateNormalsAndTangents();
			void GenerateTangents();

			const Boxf& GetAABB() const;
			std::filesystem::path GetAnimation() const;
			AnimationType GetAnimationType() const;
			std::size_t GetJointCount() const;
			ParameterList& GetMaterialData(std::size_t index);
			const ParameterList& GetMaterialData(std::size_t index) const;
			std::size_t GetMaterialCount() const;
			Skeleton* GetSkeleton();
			const Skeleton* GetSkeleton() const;
			const std::shared_ptr<SubMesh>& GetSubMesh(std::string_view identifier) const;
			const std::shared_ptr<SubMesh>& GetSubMesh(std::size_t index) const;
			std::size_t GetSubMeshCount() const;
			std::size_t GetSubMeshIndex(std::string_view identifier) const;
			UInt32 GetTriangleCount() const;
			UInt32 GetVertexCount() const;

			bool HasSubMesh(std::string_view identifier) const;
			bool HasSubMesh(std::size_t index = 0) const;

			void InvalidateAABB() const;

			bool IsAnimable() const;
			bool IsValid() const;

			void Recenter();

			void RemoveSubMesh(std::string_view identifier);
			void RemoveSubMesh(std::size_t index);

			bool SaveToFile(const std::filesystem::path& filePath, const MeshParams& params = MeshParams());
			bool SaveToStream(Stream& stream, std::string_view format, const MeshParams& params = MeshParams());

			void SetAnimation(const std::filesystem::path& animationPath);
			void SetMaterialCount(std::size_t matCount);
			void SetMaterialData(std::size_t matIndex, ParameterList data);

			void Transform(const Matrix4f& matrix);

			Mesh& operator=(const Mesh&) = delete;
			Mesh& operator=(Mesh&&) = delete;

			static inline std::shared_ptr<Mesh> Build(std::shared_ptr<StaticMesh> staticMesh);
			static inline std::shared_ptr<Mesh> Build(const Primitive& primitive, const MeshParams& params = MeshParams());
			static inline std::shared_ptr<Mesh> Build(const PrimitiveList& primitiveList, const MeshParams& params = MeshParams());

			static std::shared_ptr<Mesh> LoadFromFile(const std::filesystem::path& filePath, const MeshParams& params = MeshParams());
			static std::shared_ptr<Mesh> LoadFromMemory(const void* data, std::size_t size, const MeshParams& params = MeshParams());
			static std::shared_ptr<Mesh> LoadFromStream(Stream& stream, const MeshParams& params = MeshParams());

			// Signals:
			NazaraSignal(OnMeshInvalidateAABB, const Mesh* /*mesh*/);

		private:
			struct SubMeshData
			{
				std::shared_ptr<SubMesh> subMesh;

				NazaraSlot(SubMesh, OnSubMeshInvalidateAABB, onSubMeshInvalidated);
			};

			std::size_t m_jointCount; // Only used by skeletal meshes
			std::unordered_map<std::string, std::size_t, StringHash<>, std::equal_to<>> m_subMeshMap;
			std::vector<ParameterList> m_materialData;
			std::vector<SubMeshData> m_subMeshes;
			AnimationType m_animationType;
			mutable Boxf m_aabb;
			Skeleton m_skeleton; // Only used by skeletal meshes
			std::filesystem::path m_animationPath;
			mutable bool m_aabbUpdated;
			bool m_isValid;
	};
}

#include <Nazara/Core/Mesh.inl>

#endif // NAZARA_CORE_MESH_HPP