More abilities, refactor stealing held items

PkmnLib.Dynamic/Models/Pokemon.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics.CodeAnalysis;
 using JetBrains.Annotations;
 using PkmnLib.Dynamic.Events;
 using PkmnLib.Dynamic.Libraries;
@@ -251,6 +252,12 @@ public interface IPokemon : IScriptSource, IDeepCloneable
     /// </remarks>
     IItem? RemoveHeldItemForBattle();
 
+    /// <summary>
+    /// Tries to steal the held item of the Pokémon. If successful, the item is removed from the Pokémon and returned.
+    /// If the Pokémon does not have a held item, or the item is a form changer, this will return false.
+    /// </summary>
+    bool TryStealHeldItem([NotNullWhen(true)] out IItem? item);
+
     /// <summary>
     /// Restores the held item of a Pokémon if it was temporarily removed.
     /// </summary>
@@ -812,6 +819,25 @@ public class PokemonImpl : ScriptSource, IPokemon
         return _stolenHeldItem = RemoveHeldItem();
     }
 
+    /// <inheritdoc />
+    public bool TryStealHeldItem([NotNullWhen(true)] out IItem? item)
+    {
+        if (HeldItem is null || HeldItem.Category == ItemCategory.FormChanger)
+        {
+            item = null;
+            return false;
+        }
+        var prevent = false;
+        this.RunScriptHook(script => script.PreventHeldItemSteal(this, HeldItem, ref prevent));
+        if (prevent)
+        {
+            item = null;
+            return false;
+        }
+        item = RemoveHeldItemForBattle();
+        return item is not null;
+    }
+
     /// <inheritdoc />
     public void RestoreStolenHeldItem()
     {

PkmnLib.Dynamic/ScriptHandling/Script.cs

@@ -812,6 +812,13 @@ public abstract class Script : IDeepCloneable
     {
     }
 
+    /// <summary>
+    /// This function allows a script to prevent a held item from being stolen by an effect such as Thief or Covet.
+    /// </summary>
+    public virtual void PreventHeldItemSteal(IPokemon pokemon, IItem heldItem, ref bool prevent)
+    {
+    }
+
     /// <summary>
     /// This function allows a script to run after a held item has changed. 
     /// </summary>