Dominion.PlayerState.RequestPlayerTrashCardFromHandAndGainCard C# (CSharp) Method

        internal Card RequestPlayerTrashCardFromHandAndGainCard(
            GameState gameState,
            CardPredicate acceptableCardsToTrash,
            CostConstraint costConstraint,
            int cost,
            CardRelativeCost cardRelativeCost,
            bool isOptionalToTrash = false,
            bool isOptionalToGain = false,
            DeckPlacement defaultLocation = DeckPlacement.Discard)
        {
            Card trashedCard = this.RequestPlayerTrashCardFromHand(gameState, acceptableCardsToTrash, isOptionalToTrash);
            if (trashedCard != null)
            {
                int cardCost = cardRelativeCost == CardRelativeCost.RelativeCost ? trashedCard.CurrentCoinCost(this) + cost :
                                   cardRelativeCost == CardRelativeCost.AbsoluteCost ? cost : 0;

                CardPredicate cardPredicate;
                if (costConstraint == CostConstraint.Exactly)
                {
                    cardPredicate = acceptableCard => acceptableCard.CurrentCoinCost(this) == cardCost;
                }
                else if (costConstraint == CostConstraint.UpTo)
                {
                    cardPredicate = acceptableCard => acceptableCard.CurrentCoinCost(this) <= cardCost;
                }
                else
                {
                    throw new Exception("Invalid operation");
                }

                return this.RequestPlayerGainCardFromSupply(
                    gameState,
                    cardPredicate,
                    "",
                    isOptionalToGain,
                    defaultLocation);
            }

            return null;
        }

 public override void DoSpecializedAction(PlayerState currentPlayer, GameState gameState)
 {
     currentPlayer.RequestPlayerTrashCardFromHandAndGainCard(
         gameState,
         acceptableCard => true,
         CostConstraint.UpTo,
         5,
         CardRelativeCost.AbsoluteCost);
 }