// © 2024 Long Ly. All rights reserved. Any unauthorized use, reproduction, or distribution of this trademark is strictly prohibited and may result in legal action.

#pragma once

#include "CoreMinimal.h"
#include "GameplayTagContainer.h"
#include "UObject/Object.h"
#include "OLSCameraMode.generated.h"

/**
 * EOLSCameraModeBlendFunction
 *
 *	Blend function used for transitioning between camera modes.
 */
UENUM(BlueprintType)
enum class EOLSCameraModeBlendFunction : uint8
{
	// Does a simple linear interpolation.
	Linear,

	// Immediately accelerates, but smoothly decelerates into the target.  Ease amount controlled by the exponent.
	EaseIn,

	// Smoothly accelerates, but does not decelerate into the target.  Ease amount controlled by the exponent.
	EaseOut,

	// Smoothly accelerates and decelerates.  Ease amount controlled by the exponent.
	EaseInOut,

	COUNT	UMETA(Hidden)
};

/**
 * FOLSCameraModeView
 *
 *	View data produced by the camera mode that is used to blend camera modes.
 */
struct FOLSCameraModeView
{
public:

	FOLSCameraModeView();

	void Blend(const FOLSCameraModeView& other, float otherWeight);

public:

	FVector Location;
	FRotator Rotation;
	FRotator ControlRotation;
	float FieldOfView;
};

/**
 *	UOLSCameraMode
 *
 *	Base class for all camera modes.
 */
UCLASS(Abstract, NotBlueprintable)
class OLS_API UOLSCameraMode : public UObject
{
	GENERATED_BODY()

public:

	UOLSCameraMode();

	class UOLSCameraComponent* GetOLSCameraComponent() const;

	virtual UWorld* GetWorld() const override;

	AActor* GetTargetActor() const;

	const FOLSCameraModeView& GetCameraModeView() const;

	// Called when this camera mode is activated on the camera mode stack.
	virtual void OnActivation();

	// Called when this camera mode is deactivated on the camera mode stack.
	virtual void OnDeactivation();

	void UpdateCameraMode(float deltaTime);

	float GetBlendTime() const;
	float GetBlendWeight() const;
	void SetBlendWeight(float weight);

	FGameplayTag GetCameraTypeTag() const;

	virtual void DrawDebug(UCanvas* canvas) const;

protected:

	virtual FVector GetPivotLocation() const;
	virtual FRotator GetPivotRotation() const;

	virtual void UpdateView(float deltaTime);
	virtual void UpdateBlending(float deltaTime);
	
protected:
	
	// A tag that can be queried by gameplay code that cares when a kind of camera mode is active
	// without having to ask about a specific mode (e.g., when aiming downsights to get more accuracy)
	UPROPERTY(EditDefaultsOnly, Category = "Blending")
	FGameplayTag CameraTypeTag = FGameplayTag::EmptyTag;

	// View output produced by the camera mode.
	FOLSCameraModeView View;

	// The horizontal field of view (in degrees).
	UPROPERTY(EditDefaultsOnly, Category = "View", Meta = (UIMin = "5.0", UIMax = "170", ClampMin = "5.0", ClampMax = "170.0"))
	float FieldOfView = 0.0f;

	// Minimum view pitch (in degrees).
	UPROPERTY(EditDefaultsOnly, Category = "View", Meta = (UIMin = "-89.9", UIMax = "89.9", ClampMin = "-89.9", ClampMax = "89.9"))
	float ViewPitchMin = 0.0f;

	// Maximum view pitch (in degrees).
	UPROPERTY(EditDefaultsOnly, Category = "View", Meta = (UIMin = "-89.9", UIMax = "89.9", ClampMin = "-89.9", ClampMax = "89.9"))
	float ViewPitchMax = 0.0f;

	// How long it takes to blend in this mode.
	UPROPERTY(EditDefaultsOnly, Category = "Blending")
	float BlendTime = 0.0f;

	// Function used for blending.
	UPROPERTY(EditDefaultsOnly, Category = "Blending")
	EOLSCameraModeBlendFunction BlendFunction = EOLSCameraModeBlendFunction::Linear;

	// Exponent used by blend functions to control the shape of the curve.
	UPROPERTY(EditDefaultsOnly, Category = "Blending")
	float BlendExponent = 0.0f;

	// Linear blend alpha used to determine the blend weight.
	float BlendAlpha = 0.0f;

	// Blend weight calculated using the blend alpha and function.
	float BlendWeight = 0.0f;

protected:
	
	/** If true, skips all interpolation and puts camera in ideal location.  Automatically set to false next frame. */
	UPROPERTY(Transient)
	uint32 bShouldResetInterpolation : 1 = false;
};

/**
 * UOLSCameraModeStack
 *
 *	Stack used for blending camera modes.
 */
UCLASS()
class UOLSCameraModeStack : public UObject
{
	GENERATED_BODY()

public:

	UOLSCameraModeStack();

	void ActivateStack();
	void DeactivateStack();

	bool IsStackActivate() const;

	void PushCameraMode(TSubclassOf<UOLSCameraMode> cameraModeClass);

	bool EvaluateStack(float deltaTime, FOLSCameraModeView& outCameraModeView);

	void DrawDebug(UCanvas* canvas) const;

	// Gets the tag associated with the top layer and the blend weight of it
	void GetBlendInfo(float& outWeightOfTopLayer, FGameplayTag& outTagOfTopLayer) const;

protected:

	UOLSCameraMode* GetCameraModeInstance(TSubclassOf<UOLSCameraMode> cameraModeClass);

	void UpdateStack(float deltaTime);
	void BlendStack(FOLSCameraModeView& outCameraModeView) const;

protected:

	uint8 bIsStackActive : 1 = true;

	UPROPERTY()
	TArray<TObjectPtr<UOLSCameraMode>> CameraModeInstances;

	UPROPERTY()
	TArray<TObjectPtr<UOLSCameraMode>> CameraModeStack;
};