PKHeX/PKHeX.Core/Legality/Encounters/EncounterStatic/EncounterStaticShadow.cs

using System.Collections.Generic;

namespace PKHeX.Core;

/// <summary>
/// Shadow Pokémon Encounter found in <see cref="GameVersion.CXD"/>
/// </summary>
/// <inheritdoc cref="EncounterStatic"/>
/// <param name="ID">Initial Shadow Gauge value.</param>
/// <param name="Gauge">Initial Shadow Gauge value.</param>
/// <param name="Locks">Team Specification with required <see cref="Species"/>, <see cref="Nature"/> and Gender.</param>
// ReSharper disable NotAccessedPositionalProperty.Global
public sealed record EncounterStaticShadow(GameVersion Version, byte ID, short Gauge, TeamLock[] Locks) : EncounterStatic(Version)
{
    // ReSharper restore NotAccessedPositionalProperty.Global
    public override int Generation => 3;
    public override EntityContext Context => EntityContext.Gen3;

    /// <summary>
    /// Originates from the EReader scans (Japanese Only)
    /// </summary>
    public bool EReader => ReferenceEquals(IVs, EReaderEmpty);

    public static readonly IReadOnlyList<int> EReaderEmpty = new[] {0,0,0,0,0,0};

    protected override bool IsMatchLocation(PKM pk)
    {
        if (pk.Format != 3)
            return true; // transfer location verified later

        var met = pk.Met_Location;
        if (met == Location)
            return true;

        // XD can re-battle with Miror B
        // Realgam Tower, Rock, Oasis, Cave, Pyrite Town
        return Version == GameVersion.XD && met is (59 or 90 or 91 or 92 or 113);
    }

    protected override bool IsMatchLevel(PKM pk, EvoCriteria evo)
    {
        if (pk.Format != 3) // Met Level lost on PK3=>PK4
            return Level <= evo.LevelMax;

        return pk.Met_Level == Level;
    }

    protected override void ApplyDetails(ITrainerInfo tr, EncounterCriteria criteria, PKM pk)
    {
        base.ApplyDetails(tr, criteria, pk);
        ((IRibbonSetEvent3)pk).RibbonNational = true;
    }

    protected override void SetPINGA(PKM pk, EncounterCriteria criteria)
    {
        if (!EReader)
            SetPINGA_Regular(pk, criteria);
        else
            SetPINGA_EReader(pk);
    }

    private void SetPINGA_Regular(PKM pk, EncounterCriteria criteria)
    {
        var pi = pk.PersonalInfo;
        int gender = criteria.GetGender(-1, pi);
        int nature = (int)criteria.GetNature(Nature.Random);
        int ability = criteria.GetAbilityFromNumber(0);

        // Ensure that any generated specimen has valid Shadow Locks
        // This can be kinda slow, depending on how many locks / how strict they are.
        // Cancel this operation if too many attempts are made to prevent infinite loops.
        int ctr = 0;
        const int max = 100_000;
        do
        {
            PIDGenerator.SetRandomWildPID(pk, 3, nature, ability, gender, PIDType.CXD);
            var pidiv = MethodFinder.Analyze(pk);
            var result = LockFinder.IsAllShadowLockValid(this, pidiv, pk);
            if (result)
                break;
        }
        while (++ctr <= max);

#if DEBUG
        System.Diagnostics.Debug.Assert(ctr < 100_000);
#endif
    }

    private void SetPINGA_EReader(PKM pk)
    {
        // E-Reader have all IVs == 0
        for (int i = 0; i < IVs.Count; i++)
            pk.SetIV(i, 0);

        // All E-Reader shadows are actually nature/gender locked.
        var locked = Locks[0].Locks[^1];
        var (nature, gender) = locked.GetLock;

        // Ensure that any generated specimen has valid Shadow Locks
        // This can be kinda slow, depending on how many locks / how strict they are.
        // Cancel this operation if too many attempts are made to prevent infinite loops.
        int ctr = 0;
        const int max = 100_000;
        do
        {
            var seed = Util.Rand32();
            PIDGenerator.SetValuesFromSeedXDRNG_EReader(pk, seed);
            if (pk.Nature != nature || pk.Gender != gender)
                continue;
            var pidiv = new PIDIV(PIDType.CXD, seed);
            var result = LockFinder.IsAllShadowLockValid(this, pidiv, pk);
            if (result)
                break;
        }
        while (++ctr <= max);

#if DEBUG
        System.Diagnostics.Debug.Assert(ctr < 100_000);
#endif
    }
}