Adds several new scripts

Plugins/PkmnLib.Plugin.Gen7/Scripts/Moves/Drain.cs

@@ -0,0 +1,34 @@
+using System.Collections.Generic;
+using PkmnLib.Dynamic.Libraries;
+using PkmnLib.Dynamic.Models;
+using PkmnLib.Dynamic.ScriptHandling;
+using PkmnLib.Dynamic.ScriptHandling.Registry;
+using PkmnLib.Static.Utils;
+
+namespace PkmnLib.Plugin.Gen7.Scripts.Moves;
+
+[Script(ScriptCategory.Move, "drain")]
+public class Drain : Script
+{
+    public float DrainModifier { get; set; } = 0.5f;
+    
+    /// <inheritdoc />
+    public override void OnInitialize(IDynamicLibrary library, IReadOnlyDictionary<StringKey, object?>? parameters)
+    {
+        base.OnInitialize(library, parameters);
+        if (parameters == null)
+            return;
+        DrainModifier = parameters.GetValueOrDefault("drain_modifier") as float? ?? DrainModifier;
+    }
+
+    /// <inheritdoc />
+    public override void OnSecondaryEffect(IExecutingMove move, IPokemon target, byte hit)
+    {
+        var user = move.User;
+        var damage = move.GetHitData(target, hit).Damage;
+        var healed = (uint)(damage * DrainModifier);
+        if (move.User.HasHeldItem("big_root"))
+            healed = (uint)(healed * 1.3f);
+        user.Heal(healed, false);
+    }
+}