#pragma once

#include "CoreMinimal.h"
#include "ProceduralMeshComponent.h"
#include "Core/Tuning/DescentTune_Terrain.h"

class UProceduralMeshComponent;

namespace Descent::World
{
	/** Where a chunk is in its life (DESIGN_UE.md section 2.3). */
	enum class EChunkState : uint8
	{
		Uniform,    // classified: all rock or all water, no data (UniformValue = +-4)
		Candidate,  // may hold a surface; not filled yet (or its data was freed)
		Mixed,      // filled: Data / Cut hold P^3 samples
		Empty,      // filled once, no surface; data freed (queries use the analytic field)
	};

	/**
	 * One 20 m chunk. Owned and touched by the game thread only; a worker never sees one (jobs get copies).
	 * Sample (i, j, k) of chunk C sits at ((C * CoreN - Pad) + (i, j, k)) * VoxelM metres.
	 */
	struct FTerrainChunk
	{
		FIntVector Key = FIntVector::ZeroValue;
		EChunkState State = EChunkState::Candidate;
		float UniformValue = 4.f;
		TArray<float> Data;
		TArray<uint8> Cut;
		TArray<int32, TInlineAllocator<8>> Deposits;
		bool bDepositsKnown = false;
		bool bModified = false;      // carved at least once: its data is kept for ever
		bool bDirty = false;         // edited since the last mesh
		bool bJobInFlight = false;
		bool bMeshed = false;        // has been given its mesh (Comp may still be null when there is no terrain actor)
		uint32 Version = 0;          // incremented by every edit: a job result with another version is stale
		int32 Triangles = 0;
		int64 LastRemeshFrame = -100;
		UProceduralMeshComponent* Comp = nullptr;
		bool HasData() const { return Data.Num() == Descent::Tune::Terrain::P3; }
		FVector OriginM() const { return FVector(Key) * Descent::Tune::Terrain::ChunkM; }
		FVector CentreM() const { return (FVector(Key) + FVector(0.5)) * Descent::Tune::Terrain::ChunkM; }
	};
}