#pragma once

#include "CoreMinimal.h"
#include "Components/SceneComponent.h"
#include "Core/DescentHandle.h"
#include "CarrierCarousel.generated.h"

class AKazahTender;
class ADescentCarrier;
class UProceduralMeshComponent;

/**
 * Sub bay carousel and hoist (DESIGN_UE.md section 3.5, requirement V5: subs never clip). The geometry is pure functions in
 * carrier-local metres, so the clearance sweep of the automation test and the live `carrier.carousel.min_clearance_m` are the same code.
 */
namespace Descent::Carrier::Carousel
{
	/** A box that is only turned about Z: centre, half extents, yaw. Enough for Tenders in cradles and every bay obstacle. */
	struct FYawBox
	{
		FVector C = FVector::ZeroVector;
		FVector Half = FVector::OneVector;
		double YawDeg = 0.0;
		const TCHAR* Name = TEXT("");
	};

	/** Yaw of arm 0..2 for a hub angle: 90 + angle + 120 arm (arm 0 starts over the pool). */
	THEDESCENT_API double ArmYawDeg(int32 Arm, double AngleDeg);
	/** Where a Tender hangs: origin at the cradle (radius 6 from the hub), nose tangential (toward the bow at the launch slot). */
	THEDESCENT_API FTransform CradleLocalM(int32 Arm, double AngleDeg, double Z);
	/** The Tender's model bounds (6.99 x 3.27 x 2.51 m) around a Tender origin and yaw. */
	THEDESCENT_API FYawBox TenderBox(const FVector& OriginM, double YawDeg);
	/** Exact distance between two yaw-only boxes (0 when they intersect). */
	THEDESCENT_API double BoxDistance(const FYawBox& A, const FYawBox& B);
	/**
	 * Everything in the bay a Tender must not touch: walls, ceiling, floor around the pool, the D2 gallery and its rail, the stairs and
	 * their rail, the hub, the pipe riser and the unload boom (section 6.3, stowed; they are built in M5), the pool rails and shaft walls.
	 */
	THEDESCENT_API const TArray<FYawBox>& BayObstacles();
	/** The smallest distance from a Tender box to any bay obstacle; OutName names the obstacle. */
	THEDESCENT_API double ObstacleDistance(const FYawBox& Tender, const TCHAR** OutName = nullptr);
	/** True when a Tender at carrier-local P may dock (section 3.5: +-9 m in x, +-7 m in y of the launch column, z -34..-11). */
	THEDESCENT_API bool InDockZone(const FVector& LocalM);
}

enum class ECarouselPhase : uint8 { Idle, Raising, Rotating, Lowering };

/**
 * The carousel on the carrier: hub and three arms (a rotating blockout), a hoist carriage per arm, the three Tenders. It moves the
 * Tenders that are in a cradle, launching or docking (sim step Carousel); a Tender that is out belongs to its flight component.
 */
UCLASS(ClassGroup = (Descent))
class THEDESCENT_API UCarrierCarouselComponent : public USceneComponent
{
	GENERATED_BODY()

public:
	UCarrierCarouselComponent();

	/** Builds the blockout. Called by the carrier's BeginPlay after the rooms exist. */
	void Build();
	void Shutdown();

	/** Spawns the three Tenders into the cradles (boot step SpawnTenders). */
	void SpawnTenders();
	AKazahTender* GetTender(int32 Index) const { return Tenders.IsValidIndex(Index) ? Tenders[Index] : nullptr; }
	int32 NumTenders() const { return Tenders.Num(); }
	int32 IndexOf(const AKazahTender* T) const;

	// ---- state ----
	double GetAngleDeg() const { return AngleDeg; }
	ECarouselPhase GetPhase() const { return Phase; }
	bool IsBusy() const { return Phase != ECarouselPhase::Idle || ActiveAnim != EAnim::None; }
	double GetHoistZ() const { return HoistZ; }
	/** The arm (= Tender index) whose cradle is the hoist over the pool right now (while rotating: the one it is turning to). */
	int32 GetLaunchSlot() const { return LaunchArm; }
	bool AnyTenderOut() const;
	double GetMinClearanceM() const { return MinClearanceM; }
	/** The smallest clearance seen since the last ResetMinClearanceSeen (scenarios assert it "throughout"). */
	double GetMinClearanceSeenM() const { return MinClearanceSeenM; }
	void ResetMinClearanceSeen() { MinClearanceSeenM = 1e9; }
	int32 GetRotationsDone() const { return RotationsDone; }

	/** The Tender in the hoist cradle at BOARD with nothing moving, or null. */
	AKazahTender* TenderAtBoard() const;

	// ---- requests (false + reason when refused) ----
	bool RequestRotate(FString* OutWhyNot = nullptr);
	bool BeginLaunch(AKazahTender* T, FString* OutWhyNot = nullptr);
	bool CanDock(const AKazahTender* T, FString* OutWhyNot = nullptr) const;
	bool BeginDock(AKazahTender* T, FString* OutWhyNot = nullptr);
	/** After an implosion: the Tender is "printed" again into the hoist cradle with a full hull and 60 % power. */
	void ReprintTender(AKazahTender* T);
	/** Seconds the current launch or dock still takes (0 when none). */
	double AnimRemaining() const;

private:
	enum class EAnim : uint8 { None, Launch, Dock };

	void Step(double Dt);
	void PlaceCradled();
	void UpdateVisuals();
	void UpdateClearance();
	ADescentCarrier* Carrier() const;

	UPROPERTY(Transient) TArray<TObjectPtr<AKazahTender>> Tenders;
	UPROPERTY(Transient) TObjectPtr<USceneComponent> ArmsRoot;
	UPROPERTY(Transient) TArray<TObjectPtr<UProceduralMeshComponent>> Carriages;
	UPROPERTY(Transient) TArray<TObjectPtr<UProceduralMeshComponent>> Masts;

	double AngleDeg = 0.0;
	double RotateLeftDeg = 0.0;
	ECarouselPhase Phase = ECarouselPhase::Idle;
	double HoistZ = 0.0;
	int32 LaunchArm = 0;
	int32 RotationsDone = 0;

	EAnim ActiveAnim = EAnim::None;
	int32 AnimTender = -1;
	double AnimTime = 0.0;
	FTransform AnimFromLocal;      // dock: where the Tender was (carrier-local, uu) when E was pressed

	double MinClearanceM = 1e9;
	double MinClearanceSeenM = 1e9;
	FDescentHandle StepHandle;
	bool bBuilt = false;
};