// Copyright 2020 Phyronnaz

#pragma once

#include "CoreMinimal.h"
#include "VoxelDirection.h"
#include "VoxelContainers/VoxelStaticArray.h"
#include "VoxelData/VoxelDataAccelerator.h"
#include "VoxelRender/Meshers/VoxelMesher.h"

#define CUBIC_CHUNK_SIZE_WITH_NEIGHBORS (RENDER_CHUNK_SIZE + 2)

class FVoxelCubicMesher : public FVoxelMesher
{
public:
	using FVoxelMesher::FVoxelMesher;
	
protected:
	virtual FVoxelIntBox GetBoundsToCheckIsEmptyOn() const override final;
	virtual FVoxelIntBox GetBoundsToLock() const override final;
	virtual TVoxelSharedPtr<FVoxelChunkMesh> CreateFullChunkImpl(FVoxelMesherTimes& Times) override final;
	virtual void CreateGeometryImpl(FVoxelMesherTimes& Times, TArray<uint32>& Indices, TArray<FVector>& Vertices) override final;
	
private:
	TUniquePtr<FVoxelConstDataAccelerator> Accelerator;
	TVoxelStaticArray<FVoxelValue, CUBIC_CHUNK_SIZE_WITH_NEIGHBORS * CUBIC_CHUNK_SIZE_WITH_NEIGHBORS * CUBIC_CHUNK_SIZE_WITH_NEIGHBORS> CachedValues;

private:
	template<typename T>
	void CreateGeometryTemplate(FVoxelMesherTimes& Times, TArray<uint32>& Indices, TArray<T>& Vertices);

private:
	FVoxelValue GetValue(int32 X, int32 Y, int32 Z) const;
};

class FVoxelCubicTransitionsMesher : public FVoxelTransitionsMesher
{
public:
	using FVoxelTransitionsMesher::FVoxelTransitionsMesher;

protected:
	virtual FVoxelIntBox GetBoundsToCheckIsEmptyOn() const override final;
	virtual FVoxelIntBox GetBoundsToLock() const override final;
	virtual TVoxelSharedPtr<FVoxelChunkMesh> CreateFullChunkImpl(FVoxelMesherTimes& Times) override final;

private:
	TUniquePtr<FVoxelConstDataAccelerator> Accelerator;

private:
	template<EVoxelDirectionFlag::Type Direction, typename TVertex>
	void CreateTransitionsForDirection(FVoxelMesherTimes& Times, TArray<uint32>& Indices, TArray<TVertex>& Vertices);
	
private:
	template<EVoxelDirectionFlag::Type Direction>
	FVoxelValue GetValue(int32 InStep, int32 X, int32 Y, int32 Z) const;
	template<EVoxelDirectionFlag::Type Direction>
	FVoxelMaterial GetMaterial(int32 InStep, int32 X, int32 Y, int32 Z) const;

	// LX * HalfStep = GX
	template<EVoxelDirectionFlag::Type Direction, EVoxelDirectionFlag::Type FaceDirection, typename TVertex>
	void Add2DFace(
		int32 InStep, 
		const FVoxelMaterial& Material, 
		int32 LX, int32 LY, 
		TArray<TVertex>& Vertices, TArray<uint32>& Indices);
	
	template<EVoxelDirectionFlag::Type Direction>
	static FIntVector Local2DToGlobal(int32 InSize, int32 LX, int32 LY, int32 LZ);
};