Implement most pokeballs

Plugins/PkmnLib.Plugin.Gen7/Scripts/Items/Pokeballs/PokeballFlatModifier.cs

@@ -0,0 +1,38 @@
+namespace PkmnLib.Plugin.Gen7.Scripts.Items.Pokeballs;
+
+/// <summary>
+/// An implementation of a pokeball script that just has a flat catch rate bonus.
+/// </summary>
+[ItemScript("pokeball_flat_modifier")]
+public class PokeballFlatModifier : PokeballScript
+{
+    private float _catchModifier;
+
+    /// <inheritdoc />
+    public PokeballFlatModifier(IItem item) : base(item)
+    {
+    }
+
+    /// <inheritdoc />
+    public override void OnInitialize(IReadOnlyDictionary<StringKey, object?>? parameters)
+    {
+        var catchModifier = 1f;
+        if (parameters != null && parameters.TryGetValue("catchRate", out var catchRateObj))
+        {
+            catchModifier = catchRateObj switch
+            {
+                float catchModifierFloat => catchModifierFloat,
+                int catchModifierInt => catchModifierInt,
+                _ => catchModifier,
+            };
+        }
+
+        _catchModifier = catchModifier;
+    }
+
+    /// <inheritdoc />
+    public override void ChangeCatchRate(IPokemon target, ref byte catchRate)
+    {
+        catchRate = catchRate.MultiplyOrMax(_catchModifier);
+    }
+}