#pragma once

#include "CoreMinimal.h"
#include "Core/DescentHandle.h"
#include "Core/DescentWorldSubsystem.h"
#include "DescentLooseOre.generated.h"

class UInstancedStaticMeshComponent;

/** One loose ore chunk (DESIGN_UE.md section 2.12). Type: 0 ferrite, 1 cobalt, 2 pearl. */
struct FDescentLooseChunk
{
	FVector PosM = FVector::ZeroVector;
	FVector VelMps = FVector::ZeroVector;
	uint8 Type = 0;
};

/**
 * Loose ore (M4): a pool of at most 160 chunks. A chunk appears where the drill completes one inside a vein (the ore subsystem's
 * OnOreFreed), sinks slowly, drifts with the Shear, bounces off rock (the density field), and is pulled in and captured by a Tender's
 * suction. Stepped in sim step 8 (Ore); the Tender's tool (step 5) pulls first.
 */
UCLASS()
class THEDESCENT_API UDescentLooseOreSubsystem : public UDescentWorldSubsystem
{
	GENERATED_BODY()

public:
	static UDescentLooseOreSubsystem* Get(const UWorld* World);
	static FName TypeName(uint8 Type);

	virtual void OnWorldBeginPlay(UWorld& InWorld) override;
	virtual void Deinitialize() override;

	int32 Num() const { return Chunks.Num(); }
	const TArray<FDescentLooseChunk>& All() const { return Chunks; }
	void Spawn(uint8 Type, const FVector& PosM, const FVector& VelMps);
	void Clear() { Chunks.Reset(); }

	/**
	 * Suction (section 4.5): every chunk within Range of the nozzle and inside the cone (cos >= 0.55 to Dir, or closer than 3 m) is
	 * accelerated toward the nozzle; within 1.6 m TryCapture is asked: true removes the chunk, false pushes it back. Returns captures.
	 */
	int32 Suck(const FVector& NozzleM, const FVector& Dir, double Range, double Pull, double Dt, TFunctionRef<bool(uint8)> TryCapture);
	/** A swimmer takes the nearest chunk within Range; -1 if none (returns the type). */
	int32 TakeNearest(const FVector& PosM, double Range);

private:
	void Step(double Dt);
	void UpdateVisuals();

	TArray<FDescentLooseChunk> Chunks;
	FDescentHandle StepHandle;
	FDelegateHandle FreedHandle;
	uint32 Seed = 9001u;
	UPROPERTY(Transient) TObjectPtr<AActor> VisualActor;
	UPROPERTY(Transient) TArray<TObjectPtr<UInstancedStaticMeshComponent>> Meshes;
};