PKHeX/PKHeX.Core/PKM/Interfaces/IBattleVersion.cs

namespace PKHeX.Core
{
    /// <summary>
    /// Interface that exposes a <see cref="BattleVersion"/> for allowing a Pokémon into ranked battles if it originated from a prior game.
    /// </summary>
    public interface IBattleVersion
    {
        /// <summary>
        /// Indicates which <see cref="GameVersion"/> the Pokémon's moves were reset on.
        /// </summary>
        byte BattleVersion { get; set; }
    }

    public static class BattleVersionExtensions
    {
        public static bool IsBattleVersionValid<T>(this T pk, EvolutionHistory h) where T : PKM, IBattleVersion => pk.BattleVersion switch
        {
            0 => true,
            (int)GameVersion.SW or (int)GameVersion.SH => !(pk.SWSH || pk.BDSP || pk.LA) && pk.HasVisitedSWSH(h.Gen8),
            _ => false,
        };

        /// <summary>
        /// Resets the <see cref="PKM"/>'s moves and sets the requested version.
        /// </summary>
        /// <param name="v">Reference to the object to set the <see cref="version"/></param>
        /// <param name="pk">Reference to the same object that gets moves reset</param>
        /// <param name="version">Version to apply</param>
        public static void AdaptToBattleVersion(this IBattleVersion v, PKM pk, GameVersion version)
        {
            var moves = MoveLevelUp.GetEncounterMoves(pk, pk.CurrentLevel, version);
            pk.Move1 = pk.Move2 = pk.Move3 = pk.Move4 = 0;
            pk.RelearnMove1 = pk.RelearnMove2 = pk.RelearnMove3 = pk.RelearnMove4 = 0;
            pk.SetMoves(moves);
            pk.FixMoves();
            v.BattleVersion = (byte) version;
        }

        public static int GetMinGeneration(this IBattleVersion v)
        {
            var ver = v.BattleVersion;
            if (ver == 0)
                return 1;
            var game = (GameVersion) ver;
            if (!game.IsValidSavedVersion())
                return -1;
            var gen = game.GetGeneration();
            if (gen >= 8)
                return gen;
            return -1;
        }
    }
}