#pragma once

#include "CoreMinimal.h"
#include "Systems/DescentBuild.h"
#include "DescentAutomation.generated.h"

class ADescentOreBox;
class ADescentRefinery;

/** The arm's choice (M7, requirement U14, DESIGN_UE.md section 6.6) as a pure function. Ranks: packer outfeed 0, rack 1, refinery hopper 2. */
namespace Descent::Cargo
{
	struct FSocketView
	{
		int32 Rank = 0;
		bool bOccupied = false;      // holds a box or is reserved for one
		int32 BoxCount = 0;          // pieces in the box it holds (0: nothing to take)
		int32 Capacity = 6;          // pieces it accepts while not occupied
	};
	/** The occupied socket of the lowest rank whose box some free socket of a HIGHER rank accepts, and the highest-rank such target. */
	THEDESCENT_API bool ChooseMove(TConstArrayView<FSocketView> Sockets, int32& OutFrom, int32& OutTo);
	/** Two links in a vertical plane reaching (Dist, Height) from the shoulder: shoulder pitch and elbow pitch (relative), degrees. */
	THEDESCENT_API void TwoLinkIK(double Dist, double Height, double L1, double L2, double& OutShoulderDeg, double& OutElbowDeg);
}

/** Box Rack: four buffer sockets of rank 1. */
UCLASS()
class THEDESCENT_API ADescentBoxRack : public ADescentPlaceable
{
	GENERATED_BODY()

public:
	virtual void InitKit(const Descent::Build::FPlacement& P, FName InKit, int32 InId) override;
	virtual void EndPlay(const EEndPlayReason::Type Reason) override;
	virtual bool CanPickUp(FString* OutWhyNot = nullptr) const override;
	virtual FString GetPrompt() const override;
	virtual void Use(ADescentCharacter* User) override;

	int32 SlotBox[4] = { 0, 0, 0, 0 };
	bool SlotReserved[4] = { false, false, false, false };
	FVector SocketLocalM(int32 Slot) const;   // carrier-local metres
	int32 FreeSocket() const;
	int32 NumBoxes() const;
	bool PutBox(ADescentOreBox* Box, int32 Slot);
};

/** Handling Arm Mk I / II: moves boxes from a socket to one of a higher rank within its reach. Every joint is its own component, origin on its axis. */
UCLASS()
class THEDESCENT_API ADescentRobotArm : public ADescentPlaceable
{
	GENERATED_BODY()

public:
	virtual void InitKit(const Descent::Build::FPlacement& P, FName InKit, int32 InId) override;
	virtual void EndPlay(const EEndPlayReason::Type Reason) override;
	virtual bool CanPickUp(FString* OutWhyNot = nullptr) const override;
	virtual FString GetPrompt() const override;
	virtual void Use(ADescentCharacter* User) override;

	void StepArm(double Dt);
	bool IsMoving() const { return CycleT >= 0.0; }
	double CycleFraction() const { return CycleT < 0.0 ? 0.0 : CycleT / CycleSec; }

	int32 Mk = 1;
	double ReachM = 3.2, CycleSec = 4.0;
	bool bPower = true;
	int32 Moved = 0;
	FString Status = TEXT("IDLE - nothing in reach");

	UPROPERTY(VisibleAnywhere) TObjectPtr<USceneComponent> YawJoint;
	UPROPERTY(VisibleAnywhere) TObjectPtr<USceneComponent> Shoulder;
	UPROPERTY(VisibleAnywhere) TObjectPtr<USceneComponent> Elbow;
	UPROPERTY(VisibleAnywhere) TObjectPtr<USceneComponent> Wrist;
	UPROPERTY(VisibleAnywhere) TObjectPtr<UStaticMeshComponent> Gripper;

private:
	void Pose(const FVector& TargetLocalM);
	double CycleT = -1.0;
	TWeakObjectPtr<ADescentOreBox> Box;
	TWeakObjectPtr<ADescentBoxRack> ToRack;
	TWeakObjectPtr<ADescentRefinery> ToRefinery;
	int32 ToSlot = -1, HeldCount = 0;
	FVector FromM = FVector::ZeroVector, ToM = FVector::ZeroVector, RestM = FVector::ZeroVector;
	double L1 = 1.8, L2 = 1.8;
};