PKHeX/PKHeX.Core/Legality/Verifiers/CXDVerifier.cs

using static PKHeX.Core.LegalityCheckStrings;

namespace PKHeX.Core;

/// <summary>
/// Verifies the specific origin data of <see cref="GameVersion.CXD"/> encounters.
/// </summary>
public sealed class CXDVerifier : Verifier
{
    protected override CheckIdentifier Identifier => CheckIdentifier.Misc;

    public override void Verify(LegalityAnalysis data)
    {
        var pk = data.Entity;
        if (data.EncounterMatch is EncounterStatic3 s3)
            VerifyCXDStarterCorrelation(data, s3);
        else if (pk.Egg_Location != 0 && pk is not PB8 {Egg_Location: Locations.Default8bNone}) // can't obtain eggs in CXD
            data.AddLine(GetInvalid(LEncInvalid, CheckIdentifier.Encounter)); // invalid encounter

        if (pk.OT_Gender == 1)
            data.AddLine(GetInvalid(LG3OTGender, CheckIdentifier.Trainer));
    }

    private static void VerifyCXDStarterCorrelation(LegalityAnalysis data, EncounterStatic3 enc)
    {
        var (type, seed) = data.Info.PIDIV;
        if (type is not (PIDType.CXD or PIDType.CXDAnti or PIDType.CXD_ColoStarter))
            return; // already flagged as invalid

        var pk = data.Entity;
        bool valid = enc.Species switch
        {
            (int)Species.Eevee => LockFinder.IsXDStarterValid(seed, pk.TID, pk.SID),
            (int)Species.Espeon or (int)Species.Umbreon => type == PIDType.CXD_ColoStarter,
            _ => true,
        };
        if (!valid)
            data.AddLine(GetInvalid(LEncConditionBadRNGFrame, CheckIdentifier.PID));
    }
}