PKHeX/PKHeX.Core/Legality/Evolutions/EvolutionLegality.cs

using System;
using System.Collections.Generic;

namespace PKHeX.Core;

internal static class EvolutionLegality
{
    internal static readonly HashSet<int> FutureEvolutionsGen1 = new()
    {
        (int)Species.Crobat,
        (int)Species.Bellossom,
        (int)Species.Politoed,
        (int)Species.Espeon,
        (int)Species.Umbreon,
        (int)Species.Slowking,
        (int)Species.Steelix,
        (int)Species.Scizor,
        (int)Species.Kingdra,
        (int)Species.Porygon2,
        (int)Species.Blissey,

        (int)Species.Magnezone,
        (int)Species.Lickilicky,
        (int)Species.Rhyperior,
        (int)Species.Tangrowth,
        (int)Species.Electivire,
        (int)Species.Magmortar,
        (int)Species.Leafeon,
        (int)Species.Glaceon,
        (int)Species.PorygonZ,

        (int)Species.Sylveon,

        (int)Species.Kleavor,
    };

    private static readonly HashSet<int> FutureEvolutionsGen2 = new()
    {
        (int)Species.Ambipom,
        (int)Species.Mismagius,
        (int)Species.Honchkrow,
        (int)Species.Weavile,
        (int)Species.Magnezone,
        (int)Species.Lickilicky,
        (int)Species.Rhyperior,
        (int)Species.Tangrowth,
        (int)Species.Electivire,
        (int)Species.Magmortar,
        (int)Species.Togekiss,
        (int)Species.Yanmega,
        (int)Species.Leafeon,
        (int)Species.Glaceon,
        (int)Species.Gliscor,
        (int)Species.Mamoswine,
        (int)Species.PorygonZ,

        (int)Species.Sylveon,

        (int)Species.Wyrdeer,
        (int)Species.Ursaluna,
    };

    private static readonly HashSet<int> FutureEvolutionsGen3 = new()
    {
        (int)Species.Roserade,
        (int)Species.Ambipom,
        (int)Species.Mismagius,
        (int)Species.Honchkrow,
        (int)Species.Weavile,
        (int)Species.Magnezone,
        (int)Species.Lickilicky,
        (int)Species.Rhyperior,
        (int)Species.Tangrowth,
        (int)Species.Electivire,
        (int)Species.Magmortar,
        (int)Species.Togekiss,
        (int)Species.Yanmega,
        (int)Species.Leafeon,
        (int)Species.Glaceon,
        (int)Species.Gliscor,
        (int)Species.Mamoswine,
        (int)Species.PorygonZ,
        (int)Species.Gallade,
        (int)Species.Probopass,
        (int)Species.Dusknoir,
        (int)Species.Froslass,

        (int)Species.Sylveon,
    };

    private static readonly int[] FutureEvolutionsGen4 =
    {
        (int)Species.Sylveon,
    };

    private static readonly int[] FutureEvolutionsGen5 = FutureEvolutionsGen4;

    internal static ICollection<int> GetFutureGenEvolutions(int generation) => generation switch
    {
        1 => FutureEvolutionsGen1,
        2 => FutureEvolutionsGen2,
        3 => FutureEvolutionsGen3,
        4 => FutureEvolutionsGen4,
        5 => FutureEvolutionsGen5,
        _ => Array.Empty<int>(),
    };
}