More abilities

Plugins/PkmnLib.Plugin.Gen7/Scripts/Abilities/Forecast.cs

@@ -0,0 +1,71 @@
+namespace PkmnLib.Plugin.Gen7.Scripts.Abilities;
+
+/// <summary>
+/// Forecast is an ability that changes the Pokémon's form depending on the weather.
+/// This ability is exclusive to Castform.
+///
+/// <see href="https://bulbapedia.bulbagarden.net/wiki/Forecast_(Ability)">Bulbapedia - Forecast</see>
+/// </summary>
+[Script(ScriptCategory.Ability, "forecast")]
+public class Forecast : Script
+{
+    private IPokemon? _pokemon;
+
+    /// <inheritdoc />
+    public override void OnAddedToParent(IScriptSource source)
+    {
+        if (source is not IPokemon pokemon)
+            throw new InvalidOperationException("Forecast can only be added to a Pokemon script source.");
+        _pokemon = pokemon;
+    }
+
+    /// <inheritdoc />
+    public override void OnSwitchIn(IPokemon pokemon, byte position)
+    {
+        ChangeForm(pokemon, pokemon.BattleData?.Battle.WeatherName);
+    }
+
+    /// <inheritdoc />
+    public override void OnWeatherChange(IBattle battle, StringKey? weatherName, StringKey? oldWeatherName)
+    {
+        if (_pokemon is null)
+            return;
+
+        ChangeForm(_pokemon, weatherName);
+    }
+
+    /// <inheritdoc />
+    public override void OnRemove()
+    {
+        if (_pokemon is null)
+            return;
+
+        ChangeForm(_pokemon, null);
+    }
+
+    private static void ChangeForm(IPokemon pokemon, StringKey? weather)
+    {
+        if (pokemon.Species.Name != "castform")
+            return;
+
+        if (weather == ScriptUtils.ResolveName<Weather.HarshSunlight>() &&
+            pokemon.Species.TryGetForm("sunny", out var sunnyForm) && pokemon.Form != sunnyForm)
+        {
+            pokemon.ChangeForm(sunnyForm);
+        }
+        else if (weather == ScriptUtils.ResolveName<Weather.Rain>() &&
+                 pokemon.Species.TryGetForm("rainy", out var rainyForm) && pokemon.Form != rainyForm)
+        {
+            pokemon.ChangeForm(rainyForm);
+        }
+        else if (weather == ScriptUtils.ResolveName<Weather.Hail>() &&
+                 pokemon.Species.TryGetForm("snowy", out var snowyForm) && pokemon.Form != snowyForm)
+        {
+            pokemon.ChangeForm(snowyForm);
+        }
+        else if (pokemon.Form != pokemon.Species.GetDefaultForm())
+        {
+            pokemon.ChangeForm(pokemon.Species.GetDefaultForm());
+        }
+    }
+}