PKHeX/PKHeX.Core/Legality/Encounters/EncounterSlot/EncounterSlot8.cs

using static PKHeX.Core.OverworldCorrelation8Requirement;

namespace PKHeX.Core;

/// <summary>
/// Encounter Slot found in <see cref="GameVersion.SWSH"/>.
/// </summary>
/// <inheritdoc cref="EncounterSlot"/>
public sealed record EncounterSlot8 : EncounterSlot, IOverworldCorrelation8
{
    public readonly AreaWeather8 Weather;
    public readonly AreaSlotType8 SlotType;
    public override string LongName => $"{wild} [{SlotType}] - {Weather.ToString().Replace("_", string.Empty)}";
    public override int Generation => 8;
    public override EntityContext Context => EntityContext.Gen8;

    // Fishing are only from the hidden table (not symbol).
    public bool CanEncounterViaFishing => SlotType.CanEncounterViaFishing(Weather);
    public bool CanEncounterViaCurry
    {
        get
        {
            if (!SlotType.CanEncounterViaCurry())
                return false;

            if ((Weather & AreaWeather8.All) == 0)
                return false;

            if (EncounterArea8.IsWildArea(Location))
                return false;

            return true;
        }
    }

    public EncounterSlot8(EncounterArea8 area, ushort species, byte form, byte min, byte max, AreaWeather8 weather, AreaSlotType8 slotType) : base(area, species, form, min, max)
    {
        Weather = weather;
        SlotType = slotType;
    }

    protected override void ApplyDetails(ITrainerInfo sav, EncounterCriteria criteria, PKM pk)
    {
        bool symbol = ((EncounterArea8)Area).PermitCrossover;
        var c = symbol ? EncounterCriteria.Unrestricted : criteria;
        if (!symbol && Location is 30 or 54 && (Weather & AreaWeather8.Fishing) == 0)
            ((PK8)pk).RibbonMarkCurry = true;

        base.ApplyDetails(sav, c, pk);
        if (Weather is AreaWeather8.Heavy_Fog && EncounterArea8.IsBoostedArea60Fog(Location))
            pk.CurrentLevel = pk.Met_Level = EncounterArea8.BoostLevel;

        var req = GetRequirement(pk);
        if (req != MustHave)
        {
            pk.SetRandomEC();
            return;
        }
        // Don't bother honoring shiny state.
        Overworld8RNG.ApplyDetails(pk, c, Shiny.Random);
    }

    public OverworldCorrelation8Requirement GetRequirement(PKM pk)
    {
        if (((EncounterArea8)Area).PermitCrossover)
            return MustHave; // symbol walking overworld

        bool curry = pk is IRibbonSetMark8 {RibbonMarkCurry: true} || (pk.Species == (int)Core.Species.Shedinja && pk is IRibbonSetAffixed { AffixedRibbon:(int)RibbonIndex.MarkCurry});
        if (curry)
            return MustNotHave;

        // Tree encounters are generated via the global seed, not the u32
        if ((Weather & AreaWeather8.Shaking_Trees) != 0)
        {
            // Some tree encounters are present in the regular encounters.
            return Weather == AreaWeather8.Shaking_Trees
                ? MustNotHave
                : CanBeEither;
        }

        return MustHave;
    }

    public bool IsOverworldCorrelationCorrect(PKM pk)
    {
        var flawless = GetFlawlessIVCount(pk.Met_Level);
        return Overworld8RNG.ValidateOverworldEncounter(pk, flawless: flawless);
    }

    private int GetFlawlessIVCount(int met)
    {
        const int none = 0;
        const int any023 = -1;

        // Brilliant encounters are boosted to max level for the slot.
        if (met < LevelMax)
            return none;

        var area = (EncounterArea8) Area;
        if (area.PermitCrossover)
            return any023; // Symbol
        if ((Weather & AreaWeather8.Fishing) != 0)
            return any023; // Fishing
        return none; // Hidden
    }

    public override EncounterMatchRating GetMatchRating(PKM pk)
    {
        bool isHidden = pk.AbilityNumber == 4;
        if (isHidden && this.IsPartialMatchHidden(pk.Species, Species))
            return EncounterMatchRating.PartialMatch;

        if (pk is IRibbonSetMark8 m)
        {
            if (m.RibbonMarkCurry && (Weather & AreaWeather8.All) == 0)
                return EncounterMatchRating.DeferredErrors;
            if (m.RibbonMarkFishing && (Weather & AreaWeather8.Fishing) == 0)
                return EncounterMatchRating.DeferredErrors;

            // Check if it has a mark and the weather does not permit the mark.
            // Tree/Fishing slots should be deferred here and are checked later.
            if (!Weather.IsMarkCompatible(m))
                return EncounterMatchRating.DeferredErrors;

            // Galar Mine hidden encounters can only be found via Curry or Fishing.
            if (Location is (30 or 54) && SlotType is AreaSlotType8.HiddenMain && !m.RibbonMarkCurry && !SlotType.CanEncounterViaFishing(Weather))
                return EncounterMatchRating.DeferredErrors;
        }

        var req = GetRequirement(pk);
        return req switch
        {
            MustHave when !IsOverworldCorrelationCorrect(pk) => EncounterMatchRating.DeferredErrors,
            MustNotHave when IsOverworldCorrelationCorrect(pk) => EncounterMatchRating.DeferredErrors,
            _ => EncounterMatchRating.Match,
        };
    }
}