#pragma once

#include "CoreMinimal.h"
#include "Core/DescentHandle.h"
#include "Core/DescentWorldSubsystem.h"
#include "UI/DescentHudModel.h"
#include "DescentHudSubsystem.generated.h"

/**
 * Owns the one FDescentHudModel of the world. The seam between the systems that know things and the UI that draws:
 *
 *   // a gameplay system, from a callback on EDescentLateStep::HudModel (or anywhere on the game thread):
 *   FDescentHudModel& Hud = UDescentHudSubsystem::Get(World)->Model();
 *   Hud.DepthM = Descent::DepthOfZ(RefPointM.Z);
 *   Hud.DepthText = FDescentHudModel::FormatDepth(Hud.DepthM);
 *
 *   // the UI track:
 *   const FDescentHudModel& Hud = UDescentHudSubsystem::Get(World)->Model();   // draw it
 *
 * The subsystem itself only counts down toasts and the radio line (once per late step, before the writers run) and
 * registers the `ui.hud` part of the state dump.
 */
UCLASS()
class THEDESCENT_API UDescentHudSubsystem : public UDescentWorldSubsystem
{
	GENERATED_BODY()

public:
	static UDescentHudSubsystem* Get(const UWorld* World);

	virtual void Initialize(FSubsystemCollectionBase& Collection) override;
	virtual void Deinitialize() override;

	FDescentHudModel& Model() { return HudModel; }
	const FDescentHudModel& Model() const { return HudModel; }

	/** Late steps this model has seen (proves the housekeeping runs). */
	int64 HousekeepingCount() const { return Housekeeping; }

private:
	FDescentHudModel HudModel;
	FDescentHandle StepHandle;
	int64 Housekeeping = 0;
};