NPCLootHelper.cs

using Terraria.GameContent.ItemDropRules;
using Terraria.ModLoader;

namespace Verdant
{
    /// <summary>LITERALLY stolen from Spirit. tell GabeHasWon he SUCKS</summary>
    public static class LootHelper
    {
        public static void Add(this ILoot loot, params IItemDropRule[] rules)
        {
            foreach (var item in rules)
                loot.Add(item);
        }

        public static void AddCommon(this ILoot loot, int itemID, int chanceDenominator = 1, int minStack = 1, int maxStack = 1)
        {
            if (maxStack < minStack)
                maxStack = minStack;
            loot.Add(ItemDropRule.Common(itemID, chanceDenominator, minStack, maxStack));
        }

        //Non-generic extension methods
        //NPCLoot
        public static void AddFood(this ILoot loot, int itemID, int chanceDenominator = 1, int minStack = 1, int maxStack = 1) => loot.Add(ItemDropRule.Food(itemID, chanceDenominator, minStack, maxStack));
        public static void AddOneFromOptions(this ILoot loot, int chanceDenominator, params int[] types) => loot.Add(ItemDropRule.OneFromOptions(chanceDenominator, types));
        public static void AddBossBag(this ILoot loot, int itemID) => loot.Add(ItemDropRule.BossBag(itemID));

        //Generic extension methods
        //NPCLoot
        public static void AddCommon<T>(this ILoot loot, int chanceDenominator = 1, int minStack = 1, int maxStack = 1) where T : ModItem => loot.AddCommon(ModContent.ItemType<T>(), chanceDenominator, minStack, maxStack);
        public static void AddFood<T>(this ILoot loot, int chanceDenominator = 1, int minStack = 1, int maxStack = 1) where T : ModItem => loot.Add(ItemDropRule.Food(ModContent.ItemType<T>(), chanceDenominator, minStack, maxStack));
        public static void AddBossBag<T>(this ILoot loot) where T : ModItem => loot.Add(ItemDropRule.BossBag(ModContent.ItemType<T>()));
        public static void AddMasterModeCommonDrop<T>(this ILoot loot) where T : ModItem => loot.Add(ItemDropRule.MasterModeCommonDrop(ModContent.ItemType<T>()));
        public static void AddMasterModeDropOnAllPlayers<T>(this ILoot loot) where T : ModItem => loot.Add(ItemDropRule.MasterModeDropOnAllPlayers(ModContent.ItemType<T>()));

        public static void AddMasterModeRelicAndPet<TRelic, TPet>(this ILoot loot) where TRelic : ModItem where TPet : ModItem
        {
            loot.AddMasterModeDropOnAllPlayers<TRelic>();
            loot.AddBossBag<TPet>();
        }

        //Uh on no params generics!!! - OneFromOptions generic impl.
        //NPCLoot
        public static void AddOneFromOptions<T1, T2>(this ILoot loot, int chance = 1) where T1 : ModItem where T2 : ModItem => loot.AddOneFromOptions(chance, ModContent.ItemType<T1>(), ModContent.ItemType<T2>());
        public static void AddOneFromOptions<T1, T2, T3>(this ILoot loot, int chance = 1) where T1 : ModItem where T2 : ModItem where T3 : ModItem => loot.AddOneFromOptions(chance, ModContent.ItemType<T1>(), ModContent.ItemType<T2>(), ModContent.ItemType<T3>());
        public static void AddOneFromOptions<T1, T2, T3, T4>(this ILoot loot, int chance = 1) where T1 : ModItem where T2 : ModItem where T3 : ModItem where T4 : ModItem
            => loot.AddOneFromOptions(chance, ModContent.ItemType<T1>(), ModContent.ItemType<T2>(), ModContent.ItemType<T3>(), ModContent.ItemType<T4>());
        public static void AddOneFromOptions<T1, T2, T3, T4, T5>(this ILoot loot, int chance = 1) where T1 : ModItem where T2 : ModItem where T3 : ModItem where T4 : ModItem where T5 : ModItem
            => loot.AddOneFromOptions(chance, ModContent.ItemType<T1>(), ModContent.ItemType<T2>(), ModContent.ItemType<T3>(), ModContent.ItemType<T4>(), ModContent.ItemType<T5>());
        public static void AddOneFromOptions<T1, T2, T3, T4, T5, T6>(this ILoot loot, int chance = 1) where T1 : ModItem where T2 : ModItem where T3 : ModItem where T4 : ModItem where T5 : ModItem where T6 : ModItem
            => loot.AddOneFromOptions(chance, ModContent.ItemType<T1>(), ModContent.ItemType<T2>(), ModContent.ItemType<T3>(), ModContent.ItemType<T4>(), ModContent.ItemType<T5>(), ModContent.ItemType<T6>());
        public static void AddOneFromOptions<T1, T2, T3, T4, T5, T6, T7>(this ILoot loot, int chance = 1) where T1 : ModItem where T2 : ModItem where T3 : ModItem where T4 : ModItem where T5 : ModItem where T6 : ModItem where T7 : ModItem
            => loot.AddOneFromOptions(chance, ModContent.ItemType<T1>(), ModContent.ItemType<T2>(), ModContent.ItemType<T3>(), ModContent.ItemType<T4>(), ModContent.ItemType<T5>(), ModContent.ItemType<T6>(), ModContent.ItemType<T7>());
    }
}