#pragma once

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

class UAudioComponent;
class USoundWaveProcedural;

/** Sound (M9, requirement V3; DESIGN_UE.md section 8.4). Every sound is rendered in code when the world starts: no asset, no import step. */
namespace Descent::Audio
{
	constexpr int32 SampleRate = 22050;
	constexpr double AirLowPassHz = 5200.0, TenderLowPassHz = 2400.0, SwimLowPassHz = 1300.0;
	THEDESCENT_API const TArray<FName>& LoopNames();
	/** 16-bit mono PCM of a loop (4 s) or a one-shot. False for an unknown name. */
	THEDESCENT_API bool Render(FName Name, TArray<int16>& Out);
}

struct FDescentLoopState
{
	float Volume = 0.f, Pitch = 1.f;
};

struct FDescentOneShot
{
	FName Name;
	double SimTime = 0.0;
	float Volume = 1.f;
};

/** Owns one audio component per loop and sets volume, pitch and low-pass every frame; plays one-shots. The `audio` state section shows what it does. */
UCLASS()
class THEDESCENT_API UDescentAudioSubsystem : public UDescentWorldSubsystem
{
	GENERATED_BODY()

public:
	static UDescentAudioSubsystem* Get(const UWorld* World);
	virtual void OnWorldBeginPlay(UWorld& InWorld) override;
	virtual void Deinitialize() override;

	void OneShot(FName Name, float Volume = 1.f);
	const FDescentLoopState* FindLoop(FName Name) const { return Loops.Find(Name); }
	bool HadOneShot(FName Name) const;

	TMap<FName, FDescentLoopState> Loops;
	TArray<FDescentOneShot> OneShots;   // the last 20
	double MasterLowPassHz = Descent::Audio::AirLowPassHz;
	bool bDevice = false;

private:
	void Step(double Dt);
	void EnsureComponents();
	TSharedPtr<TArray<int16>> Pcm(FName Name);

	TMap<FName, TSharedPtr<TArray<int16>>> Cache;
	FDescentHandle StepHandle;
	int32 NextShot = 0;
	UPROPERTY(Transient) TObjectPtr<AActor> Owner;
	UPROPERTY(Transient) TMap<FName, TObjectPtr<UAudioComponent>> LoopComps;
	UPROPERTY(Transient) TArray<TObjectPtr<UAudioComponent>> ShotComps;
	UPROPERTY(Transient) TArray<TObjectPtr<USoundWaveProcedural>> ShotWaves;
	UPROPERTY(Transient) TArray<TObjectPtr<USoundWaveProcedural>> LoopWaves;
};