LyraStarterGame/Source/LyraGame/AbilitySystem/Abilities/LyraAbilityCost.h

// Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include "CoreMinimal.h"
#include "GameplayAbilitySpec.h"
#include "Abilities/GameplayAbility.h"
#include "LyraAbilityCost.generated.h"

class ULyraGameplayAbility;

/**
 * ULyraAbilityCost
 *
 * Base class for costs that a LyraGameplayAbility has (e.g., ammo or charges)
 */
UCLASS(MinimalAPI, DefaultToInstanced, EditInlineNew, Abstract)
class ULyraAbilityCost : public UObject
{
	GENERATED_BODY()

public:
	ULyraAbilityCost()
	{
	}

	/**
	 * Checks if we can afford this cost.
	 *
	 * A failure reason tag can be added to OptionalRelevantTags (if non-null), which can be queried
	 * elsewhere to determine how to provide user feedback (e.g., a clicking noise if a weapon is out of ammo)
	 * 
	 * Ability and ActorInfo are guaranteed to be non-null on entry, but OptionalRelevantTags can be nullptr.
	 * 
	 * @return true if we can pay for the ability, false otherwise.
	 */
	virtual bool CheckCost(const ULyraGameplayAbility* Ability, const FGameplayAbilitySpecHandle Handle, const FGameplayAbilityActorInfo* ActorInfo, FGameplayTagContainer* OptionalRelevantTags) const
	{
		return true;
	}

	/**
	 * Applies the ability's cost to the target
	 *
	 * Notes:
	 * - Your implementation don't need to check ShouldOnlyApplyCostOnHit(), the caller does that for you.
 	 * - Ability and ActorInfo are guaranteed to be non-null on entry.
	 */
	virtual void ApplyCost(const ULyraGameplayAbility* Ability, const FGameplayAbilitySpecHandle Handle, const FGameplayAbilityActorInfo* ActorInfo, const FGameplayAbilityActivationInfo ActivationInfo)
	{
	}

	/** If true, this cost should only be applied if this ability hits successfully */
	bool ShouldOnlyApplyCostOnHit() const { return bOnlyApplyCostOnHit; }

protected:
	/** If true, this cost should only be applied if this ability hits successfully */
	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category=Costs)
	bool bOnlyApplyCostOnHit = false;
};