using System;
using System.Collections.Generic;
using static System.Buffers.Binary.BinaryPrimitives;

namespace PKHeX.Core;

/// <summary>
/// Generation 2 <see cref="SaveFile"/> object.
/// </summary>
public sealed class SAV2 : SaveFile, ILangDeviantSave, IEventFlagArray, IEventWorkArray<byte>, IBoxDetailName, IDaycareStorage, IDaycareEggState
{
    protected internal override string ShortSummary => $"{OT} ({Version}) - {PlayTimeString}";
    public override string Extension => ".sav";
    public bool IsVirtualConsole => State.Exportable && Metadata.FileName is { } s && s.StartsWith("sav", StringComparison.Ordinal) && s.Contains(".dat"); // default to GB-Era for non-exportable

    public int SaveRevision => Japanese ? 0 : !Korean ? 1 : 2;
    public string SaveRevisionString => (Japanese ? "J" : !Korean ? "U" : "K") + (IsVirtualConsole ? "VC" : "GB");
    public bool Japanese { get; }
    public bool Korean { get; }
    public override int Language => Japanese ? 1 : Korean ? (int)LanguageID.Korean : -1;

    public override PersonalTable2 Personal { get; }
    public override ReadOnlySpan<ushort> HeldItems => Legal.HeldItems_GSC;

    public override IReadOnlyList<string> PKMExtensions => Array.FindAll(PKM.Extensions, f =>
    {
        int gen = f[^1] - 0x30;
        if (Korean)
            return gen == 2;
        return gen is 1 or 2;
    });

    public SAV2(GameVersion version = GameVersion.C, LanguageID lang = LanguageID.English) : base(SaveUtil.SIZE_G2RAW_J)
    {
        Version = version;
        switch (lang)
        {
            case LanguageID.Japanese:
                Japanese = true;
                break;
            case LanguageID.Korean:
                Korean = true;
                break;
            // otherwise, both false
        }
        Offsets = new SAV2Offsets(this);
        Personal = Version == GameVersion.GS ? PersonalTable.GS : PersonalTable.C;
        Initialize();
        ClearBoxes();
    }

    public SAV2(byte[] data, GameVersion versionOverride = GameVersion.Any) : base(data)
    {
        Version = versionOverride != GameVersion.Any ? versionOverride : SaveUtil.GetIsG2SAV(Data);
        Japanese = SaveUtil.GetIsG2SAVJ(Data) != GameVersion.Invalid;
        if (Version != GameVersion.C && !Japanese)
            Korean = SaveUtil.GetIsG2SAVK(Data) != GameVersion.Invalid;

        Offsets = new SAV2Offsets(this);
        Personal = Version == GameVersion.GS ? PersonalTable.GS : PersonalTable.C;
        Initialize();
    }

    private void Initialize()
    {
        Box = Data.Length;
        Array.Resize(ref Data, Data.Length + SIZE_RESERVED);
        Party = GetPartyOffset(0);

        // Stash boxes after the save file's end.
        int splitAtIndex = (Japanese ? 6 : 7);
        int stored = SIZE_STOREDBOX;
        int baseDest = Data.Length - SIZE_RESERVED;
        var capacity = Japanese ? PokeListType.StoredJP : PokeListType.Stored;
        for (int i = 0; i < BoxCount; i++)
        {
            int ofs = GetBoxRawDataOffset(i, splitAtIndex);
            var box = Data.AsSpan(ofs, stored).ToArray();
            var boxDest = baseDest + (i * SIZE_BOX);
            var boxPL = new PokeList2(box, capacity, Japanese);
            for (int j = 0; j < boxPL.Pokemon.Length; j++)
            {
                var dest = boxDest + (j * SIZE_STORED);
                var pkDat = (j < boxPL.Count)
                    ? new PokeList2(boxPL[j]).Write()
                    : new byte[PokeList2.GetDataLength(PokeListType.Single, Japanese)];
                pkDat.CopyTo(Data, dest);
            }
        }

        var current = Data.AsSpan(Offsets.CurrentBox, stored).ToArray();
        var curBoxPL = new PokeList2(current, capacity, Japanese);
        var curDest = baseDest + (CurrentBox * SIZE_BOX);
        for (int i = 0; i < curBoxPL.Pokemon.Length; i++)
        {
            var dest = curDest + (i * SIZE_STORED);
            var pkDat = i < curBoxPL.Count
                ? new PokeList2(curBoxPL[i]).Write()
                : new byte[PokeList2.GetDataLength(PokeListType.Single, Japanese)];
            pkDat.CopyTo(Data, dest);
        }

        var party = Data.AsSpan(Offsets.Party, SIZE_STOREDPARTY).ToArray();
        var partyPL = new PokeList2(party, PokeListType.Party, Japanese);
        for (int i = 0; i < partyPL.Pokemon.Length; i++)
        {
            var dest = GetPartyOffset(i);
            var pkDat = i < partyPL.Count
                ? new PokeList2(partyPL[i]).Write()
                : new byte[PokeList2.GetDataLength(PokeListType.Single, Japanese)];
            pkDat.CopyTo(Data, dest);
        }

        if (Offsets.Daycare >= 0)
        {
            int offset = Offsets.Daycare;

            offset++;
            var pk1 = ReadPKMFromOffset(offset); // parent 1
            var daycare1 = new PokeList2(pk1);
            offset += (StringLength * 2) + 0x20; // nick/ot/pk
            offset++;
            //byte steps = Data[offset];
            offset++;
            //byte BreedMotherOrNonDitto = Data[offset];
            offset++;
            var pk2 = ReadPKMFromOffset(offset); // parent 2
            var daycare2 = new PokeList2(pk2);
            offset += (StringLength * 2) + PokeCrypto.SIZE_2STORED; // nick/ot/pk
            var pk3 = ReadPKMFromOffset(offset); // egg!
            pk3.IsEgg = true;
            var daycare3 = new PokeList2(pk3);

            daycare1.Write().CopyTo(Data, GetPartyOffset(7 + (0 * 2)));
            daycare2.Write().CopyTo(Data, GetPartyOffset(7 + (1 * 2)));
            daycare3.Write().CopyTo(Data, GetPartyOffset(7 + (2 * 2)));
        }
    }

    public override bool HasPokeDex => true;

    private int EventFlag => Offsets.EventFlag;
    private int EventWork => Offsets.EventWork;

    private PK2 ReadPKMFromOffset(int offset)
    {
        var stringLength = StringLength;
        var span = Data.AsSpan(offset);

        var pkData = span.Slice(stringLength * 2, PokeCrypto.SIZE_2STORED).ToArray();
        var pk = new PK2(pkData, jp: Japanese);

        var nick = span[..stringLength];
        var ot = span.Slice(stringLength, stringLength);
        nick.CopyTo(pk.NicknameTrash);
        ot.CopyTo(pk.OriginalTrainerTrash);

        return pk;
    }

    private const int SIZE_RESERVED = 0x8000; // unpacked box data
    private readonly SAV2Offsets Offsets;

    private int GetBoxRawDataOffset(int i, int splitAtIndex)
    {
        if (i < splitAtIndex)
            return 0x4000 + (i * (SIZE_STOREDBOX + 2));
        return 0x6000 + ((i - splitAtIndex) * (SIZE_STOREDBOX + 2));
    }

    protected override byte[] GetFinalData()
    {
        int splitAtIndex = (Japanese ? 6 : 7);
        for (int i = 0; i < BoxCount; i++)
        {
            var boxPL = new PokeList2(Japanese ? PokeListType.StoredJP : PokeListType.Stored, Japanese);
            int slot = 0;
            for (int j = 0; j < boxPL.Pokemon.Length; j++)
            {
                var ofs = GetBoxOffset(i) + (j * SIZE_STORED);
                var data = Data.AsSpan(ofs, SIZE_STORED).ToArray();
                PK2 boxPK = GetPKM(data);
                if (boxPK.Species > 0)
                    boxPL[slot++] = boxPK;
            }

            int src = GetBoxRawDataOffset(i, splitAtIndex);
            boxPL.Write().CopyTo(Data, src);
            if (i == CurrentBox)
                boxPL.Write().CopyTo(Data, Offsets.CurrentBox);
        }

        var partyPL = new PokeList2(PokeListType.Party, Japanese);
        int pSlot = 0;
        for (int i = 0; i < 6; i++)
        {
            var ofs = GetPartyOffset(i);
            var data = Data.AsSpan(ofs, SIZE_STORED).ToArray();
            PK2 partyPK = GetPKM(data);
            if (partyPK.Species > 0)
                partyPL[pSlot++] = partyPK;
        }
        partyPL.Write().CopyTo(Data, Offsets.Party);

        SetChecksums();
        if (Japanese)
        {
            switch (Version)
            {
                case GameVersion.GS: Data.AsSpan(Offsets.Trainer1, 0xC83).CopyTo(Data.AsSpan(0x7209)); break;
                case GameVersion.C:  Data.AsSpan(Offsets.Trainer1, 0xADA).CopyTo(Data.AsSpan(0x7209)); break;
            }
        }
        else if (Korean)
        {
            // Calculate oddball checksum
            ushort sum = 0;
            Span<(ushort, ushort)> offsetpairs =
            [
                (0x106B, 0x1533),
                (0x1534, 0x1A12),
                (0x1A13, 0x1C38),
                (0x3DD8, 0x3F79),
                (0x7E39, 0x7E6A),
            ];
            foreach (var p in offsetpairs)
            {
                for (int i = p.Item1; i < p.Item2; i++)
                    sum += Data[i];
            }
            WriteUInt16LittleEndian(Data.AsSpan(0x7E6B), sum);
        }
        else
        {
            switch (Version)
            {
                case GameVersion.GS:
                    Array.Copy(Data, 0x2009, Data, 0x15C7, 0x222F - 0x2009);
                    Array.Copy(Data, 0x222F, Data, 0x3D69, 0x23D9 - 0x222F);
                    Array.Copy(Data, 0x23D9, Data, 0x0C6B, 0x2856 - 0x23D9);
                    Array.Copy(Data, 0x2856, Data, 0x7E39, 0x288A - 0x2856);
                    Array.Copy(Data, 0x288A, Data, 0x10E8, 0x2D69 - 0x288A);
                    break;
                case GameVersion.C:
                    Array.Copy(Data, 0x2009, Data, 0x1209, 0xB7A);
                    break;
            }
        }
        return Data[..^SIZE_RESERVED];
    }

    // Configuration
    protected override SAV2 CloneInternal() => new(Write(), Version);

    protected override int SIZE_STORED => Japanese ? PokeCrypto.SIZE_2JLIST : PokeCrypto.SIZE_2ULIST;
    protected override int SIZE_PARTY => Japanese ? PokeCrypto.SIZE_2JLIST : PokeCrypto.SIZE_2ULIST;
    public override PK2 BlankPKM => new(jp: Japanese);
    public override Type PKMType => typeof(PK2);

    private int SIZE_BOX => BoxSlotCount*SIZE_STORED;
    private int SIZE_STOREDBOX => PokeList2.GetDataLength(Japanese ? PokeListType.StoredJP : PokeListType.Stored, Japanese);
    private int SIZE_STOREDPARTY => PokeList2.GetDataLength(PokeListType.Party, Japanese);

    public override ushort MaxMoveID => Legal.MaxMoveID_2;
    public override ushort MaxSpeciesID => Legal.MaxSpeciesID_2;
    public override int MaxAbilityID => Legal.MaxAbilityID_2;
    public override int MaxItemID => Legal.MaxItemID_2;
    public override int MaxBallID => 0; // unused
    public override GameVersion MaxGameID => GameVersion.Gen2; // unused
    public override int MaxMoney => 999999;
    public override int MaxCoins => 9999;

    public override bool IsPKMPresent(ReadOnlySpan<byte> data) => EntityDetection.IsPresentGB(data);

    public int EventWorkCount => 0x100;
    public int EventFlagCount => 2000;

    public override int BoxCount => Japanese ? 9 : 14;
    public override int MaxEV => EffortValues.Max12;
    public override int MaxIV => 15;
    public override byte Generation => 2;
    public override EntityContext Context => EntityContext.Gen2;
    public override int MaxStringLengthOT => Japanese || Korean ? 5 : 7;
    public override int MaxStringLengthNickname => Japanese || Korean ? 5 : 10;
    public override int BoxSlotCount => Japanese ? 30 : 20;

    public override bool HasParty => true;
    private int StringLength => Japanese ? GBPKML.StringLengthJapanese : GBPKML.StringLengthNotJapan;

    // Checksums
    private ushort GetChecksum()
    {
        ushort sum = 0;
        for (int i = Offsets.Trainer1; i <= Offsets.AccumulatedChecksumEnd; i++)
            sum += Data[i];
        return sum;
    }

    protected override void SetChecksums()
    {
        ushort accum = GetChecksum();
        WriteUInt16LittleEndian(Data.AsSpan(Offsets.OverallChecksumPosition), accum);
        WriteUInt16LittleEndian(Data.AsSpan(Offsets.OverallChecksumPosition2), accum);
    }

    public override bool ChecksumsValid => !ChecksumInfo.Contains("Invalid");

    public override string ChecksumInfo
    {
        get
        {
            ushort accum = GetChecksum();
            ushort actual = ReadUInt16LittleEndian(Data.AsSpan(Offsets.OverallChecksumPosition));
            ushort actual2 = ReadUInt16LittleEndian(Data.AsSpan(Offsets.OverallChecksumPosition2));

            bool checksum1Valid = (accum == actual);
            bool checksum2Valid = (accum == actual2);
            static string valid(bool s) => s ? "Valid" : "Invalid";
            return $"Checksum 1 {valid(checksum1Valid)}, Checksum 2 {valid(checksum2Valid)}.";
        }
    }

    // Trainer Info
    public override GameVersion Version { get; set; }

    public override string OT
    {
        get => GetString(Data.AsSpan(Offsets.Trainer1 + 2, (Korean ? 2 : 1) * MaxStringLengthOT));
        set => SetString(Data.AsSpan(Offsets.Trainer1 + 2, (Korean ? 2 : 1) * MaxStringLengthOT), value, 8, StringConverterOption.Clear50);
    }

    public Span<byte> OriginalTrainerTrash
    {
        get => Data.AsSpan(Offsets.Trainer1 + 2, StringLength);
        set { if (value.Length == StringLength) value.CopyTo(Data.AsSpan(Offsets.Trainer1 + 2)); }
    }

    public string Rival
    {
        get => GetString(Data.AsSpan(Offsets.Rival, (Korean ? 2 : 1) * MaxStringLengthOT));
        set => SetString(Data.AsSpan(Offsets.Rival, (Korean ? 2 : 1) * MaxStringLengthOT), value, 8, StringConverterOption.Clear50);
    }

    public Span<byte> Rival_Trash
    {
        get => Data.AsSpan(Offsets.Rival, StringLength);
        set { if (value.Length == StringLength) value.CopyTo(Data.AsSpan(Offsets.Rival)); }
    }

    public override byte Gender
    {
        get => Version == GameVersion.C ? Data[Offsets.Gender] : (byte)0;
        set
        {
            if (Version != GameVersion.C)
                return;
            Data[Offsets.Gender] = value;
            Data[Offsets.Palette] = value;
        }
    }

    public byte Palette
    {
        get => Data[Offsets.Palette];
        set => Data[Offsets.Palette] = value;
    }

    public override uint ID32
    {
        get => TID16;
        set => TID16 = (ushort)value;
    }

    public override ushort TID16
    {
        get => ReadUInt16BigEndian(Data.AsSpan(Offsets.Trainer1));
        set => WriteUInt16BigEndian(Data.AsSpan(Offsets.Trainer1), value);
    }

    public override ushort SID16 { get => 0; set { } }

    public override int PlayedHours
    {
        get => ReadUInt16BigEndian(Data.AsSpan(Offsets.TimePlayed));
        set => WriteUInt16BigEndian(Data.AsSpan(Offsets.TimePlayed), (ushort)value);
    }

    public override int PlayedMinutes
    {
        get => Data[Offsets.TimePlayed + 2];
        set => Data[Offsets.TimePlayed + 2] = (byte)value;
    }

    public override int PlayedSeconds
    {
        get => Data[Offsets.TimePlayed + 3];
        set => Data[Offsets.TimePlayed + 3] = (byte)value;
    }

    public int Badges
    {
        get => ReadUInt16LittleEndian(Data.AsSpan(Offsets.JohtoBadges));
        set { if (value < 0) return; WriteUInt16LittleEndian(Data.AsSpan(Offsets.JohtoBadges), (ushort)value); }
    }

    private byte Options
    {
        get => Data[Offsets.Options];
        set => Data[Offsets.Options] = value;
    }

    public bool BattleEffects
    {
        get => (Options & 0x80) == 0;
        set => Options = (byte)((Options & 0x7F) | (value ? 0 : 0x80));
    }

    public bool BattleStyleSwitch
    {
        get => (Options & 0x40) == 0;
        set => Options = (byte)((Options & 0xBF) | (value ? 0 : 0x40));
    }

    public int Sound
    {
        get => (Options & 0x30) >> 4;
        set => Options = (byte)((Options & 0xCF) | ((value != 0 ? 2 : 0) << 4)); // Stereo 2, Mono 0
    }

    public int TextSpeed
    {
        get => Options & 0x7;
        set => Options = (byte)((Options & 0xF8) | (value & 7));
    }

    public bool SaveFileExists
    {
        get => Data[Offsets.Options + 1] == 1;
        set => Data[Offsets.Options + 1] = value ? (byte)1 : (byte)0;
    }

    public int TextBoxFrame // 3bits
    {
        get => Data[Offsets.Options + 2] & 0b0000_0111;
        set => Data[Offsets.Options + 2] = (byte)((Data[Offsets.Options + 2] & 0b1111_1000) | (value & 0b0000_0111));
    }

    public int TextBoxFlags { get => Data[Offsets.Options + 3]; set => Data[Offsets.Options + 3] = (byte)value; }

    public bool TextBoxFrameDelay1 // bit 0
    {
        get => (TextBoxFlags & 0x01) == 0x01;
        set => TextBoxFlags = (TextBoxFlags & ~0x01) | (value ? 0x01 : 0);
    }

    public bool TextBoxFrameDelayNone // bit 4
    {
        get => (TextBoxFlags & 0x10) == 0x10;
        set => TextBoxFlags = (TextBoxFlags & ~0x10) | (value ? 0x10 : 0);
    }

    public byte GBPrinterBrightness { get => Data[Offsets.Options + 4]; set => Data[Offsets.Options + 4] = value; }

    public bool MenuAccountOn
    {
        get => Data[Offsets.Options + 5] == 1;
        set => Data[Offsets.Options + 5] = value ? (byte)1 : (byte)0;
    }

    // 3 bytes
    public override uint Money
    {
        get => ReadUInt32BigEndian(Data.AsSpan(Offsets.Money)) >> 8;
        set
        {
            var clamp = (uint)Math.Min(value, MaxMoney);
            var toWrite = (clamp << 8) | Data[Offsets.Money + 3];
            WriteUInt32BigEndian(Data.AsSpan(Offsets.Money), toWrite);
        }
    }

    public uint Coin
    {
        get => ReadUInt16BigEndian(Data.AsSpan(Offsets.Money + 7));
        set
        {
            var clamped = (ushort)Math.Min(value, MaxCoins);
            WriteUInt16BigEndian(Data.AsSpan(Offsets.Money + 7), clamped);
        }
    }

    public byte BlueCardPoints
    {
        get
        {
            int ofs = Offsets.BlueCardPoints;
            if (ofs == -1)
                return 0;
            return Data[ofs];
        }
        set
        {
            int ofs = Offsets.BlueCardPoints;
            if (ofs == -1)
                return;
            Data[ofs] = value;
        }
    }

    public byte MysteryGiftItem
    {
        get
        {
            int ofs = Offsets.MysteryGiftItem;
            if (ofs == -1)
                return 0;
            if (GetEventFlag(1809))
                return 0;
            return Data[ofs];
        }
        set
        {
            int ofs = Offsets.MysteryGiftItem;
            if (ofs == -1)
                return;

            SetEventFlag(1809, value == 0);
            Data[ofs] = value;
        }
    }

    public bool IsMysteryGiftUnlocked
    {
        get
        {
            int ofs = Offsets.MysteryGiftIsUnlocked;
            if (ofs == -1)
                return false;
            return (sbyte)Data[ofs] >= 0x00; // -1 is disabled; [0,5] is unlocked
        }
        set
        {
            int ofs = Offsets.MysteryGiftIsUnlocked;
            if (ofs == -1)
                return;

            Data[ofs] = (byte)(value ? 0x00 : 0xFF);
            Data[ofs + 2] = Data[ofs];
        }
    }

    public override IReadOnlyList<InventoryPouch> Inventory
    {
        get
        {
            var info = Version == GameVersion.C ? ItemStorage2.InstanceC : ItemStorage2.InstanceGS;
            InventoryPouch[] pouch =
            [
                new InventoryPouchGB(InventoryType.TMHMs, info, 99, Offsets.PouchTMHM, 57),
                new InventoryPouchGB(InventoryType.Items, info, 99, Offsets.PouchItem, 20),
                new InventoryPouchGB(InventoryType.KeyItems, info, 99, Offsets.PouchKey, 26),
                new InventoryPouchGB(InventoryType.Balls, info, 99, Offsets.PouchBall, 12),
                new InventoryPouchGB(InventoryType.PCItems, info, 99, Offsets.PouchPC, 50),
            ];
            return pouch.LoadAll(Data);
        }
        set => value.SaveAll(Data);
    }

    public ref byte DaycareFlagByte(int index)
    {
        var offset = GetDaycareOffset(index);
        return ref Data[offset];
    }

    private int GetDaycareOffset(int index)
    {
        int offset = Offsets.Daycare;
        if (index != 0)
            offset += (StringLength * 2) + PokeCrypto.SIZE_2STORED + 1;
        return offset;
    }

    public int DaycareSlotCount => 2;
    private int GetDaycareSlotOffset(int slot) => GetPartyOffset(7 + (slot * 2));
    public Memory<byte> GetDaycareSlot(int slot) => Data.AsMemory(GetDaycareSlotOffset(slot), SIZE_STORED);
    public Memory<byte> GetDaycareEgg() => Data.AsMemory(GetDaycareSlotOffset(2), SIZE_STORED);
    public bool IsDaycareOccupied(int slot) => (DaycareFlagByte(slot) & 1) != 0;

    public void SetDaycareOccupied(int slot, bool occupied)
    {
        if (occupied)
            DaycareFlagByte(slot) |= 1;
        else
            DaycareFlagByte(slot) &= 0xFE;
    }

    // bit 6 of the first flag byte
    public bool IsEggAvailable { get => (DaycareFlagByte(0) & 0x40) != 0; set => DaycareFlagByte(0) = (byte)((DaycareFlagByte(0) & 0xBF) | (value ? 0x40 : 0)); }

    // Storage
    public override int PartyCount
    {
        get => Data[Offsets.Party]; protected set => Data[Offsets.Party] = (byte)value;
    }

    public override int GetBoxOffset(int box)
    {
        return Data.Length - SIZE_RESERVED + (box * SIZE_BOX);
    }

    public override int GetPartyOffset(int slot)
    {
        return Data.Length - SIZE_RESERVED + (BoxCount * SIZE_BOX) + (slot * SIZE_STORED);
    }

    public override int CurrentBox
    {
        get => Data[Offsets.CurrentBoxIndex] & 0x7F;
        set => Data[Offsets.CurrentBoxIndex] = (byte)((Data[Offsets.CurrentBoxIndex] & 0x80) | (value & 0x7F));
    }

    public bool CurrentBoxChanged
    {
        get => (Data[Offsets.CurrentBoxIndex] & 0x80) != 0;
        set => Data[Offsets.CurrentBoxIndex] = (byte)((Data[Offsets.CurrentBoxIndex] & 0x7F) | (byte)(value ? 0x80 : 0));
    }

    public string GetBoxName(int box) => GetString(GetBoxNameSpan(box));

    private Span<byte> GetBoxNameSpan(int box)
    {
        int len = Korean ? 17 : 9;
        return Data.AsSpan(Offsets.BoxNames + (box * len), len);
    }

    public void SetBoxName(int box, ReadOnlySpan<char> value)
    {
        var span = GetBoxNameSpan(box);
        SetString(span, value, 8, StringConverterOption.Clear50);
    }

    protected override PK2 GetPKM(byte[] data)
    {
        if (data.Length == SIZE_STORED)
            return new PokeList2(data, PokeListType.Single, Japanese)[0];
        return new(data);
    }

    protected override byte[] DecryptPKM(byte[] data)
    {
        return data;
    }

    // Pokédex
    protected override void SetDex(PKM pk)
    {
        ushort species = pk.Species;
        if (species is 0 or > Legal.MaxSpeciesID_2)
            return;
        if (pk.IsEgg)
            return;

        SetCaught(pk.Species, true);
        SetSeen(pk.Species, true);
    }

    private void SetUnownFormFlags()
    {
        // Give all Unown caught to prevent a crash on Pokédex view
        for (int i = 1; i <= 26; i++)
            Data[Offsets.PokedexSeen + 0x1F + i] = (byte)i;
        if (UnownFirstSeen == 0) // Invalid
            UnownFirstSeen = 1; // A
    }

    /// <summary>
    /// Toggles the availability of Unown letter groups in the Wild
    /// </summary>
    /// <remarks>
    /// Max value of 0x0F, 4 bitflags
    /// 1 lsh 0: A, B, C, D, E, F, G, H, I, J, K
    /// 1 lsh 1: L, M, N, O, P, Q, R
    /// 1 lsh 2: S, T, U, V, W
    /// 1 lsh 3: X, Y, Z
    /// </remarks>
    public int UnownUnlocked
    {
        get => Data[Offsets.PokedexSeen + 0x1F + 27];
        set => Data[Offsets.PokedexSeen + 0x1F + 27] = (byte)value;
    }

    /// <summary>
    /// Unlocks all Unown letters/forms in the wild.
    /// </summary>
    public void UnownUnlockAll() => UnownUnlocked = 0x0F; // all 4 bitflags

    /// <summary>
    /// Flag that determines if Unown Letters are available in the wild: A, B, C, D, E, F, G, H, I, J, K
    /// </summary>
    public bool UnownUnlocked0
    {
        get => (UnownUnlocked & (1 << 0)) == 1 << 0;
        set => UnownUnlocked = (UnownUnlocked & ~(1 << 0)) | ((value ? 1 : 0) << 0);
    }

    /// <summary>
    /// Flag that determines if Unown Letters are available in the wild: L, M, N, O, P, Q, R
    /// </summary>
    public bool UnownUnlocked1
    {
        get => (UnownUnlocked & (1 << 1)) == 1 << 1;
        set => UnownUnlocked = (UnownUnlocked & ~(1 << 1)) | ((value ? 1 : 0) << 1);
    }

    /// <summary>
    /// Flag that determines if Unown Letters are available in the wild: S, T, U, V, W
    /// </summary>
    public bool UnownUnlocked2
    {
        get => (UnownUnlocked & (1 << 2)) == 1 << 2;
        set => UnownUnlocked = (UnownUnlocked & ~(1 << 2)) | ((value ? 1 : 0) << 2);
    }

    /// <summary>
    /// Flag that determines if Unown Letters are available in the wild: X, Y, Z
    /// </summary>
    public bool UnownUnlocked3
    {
        get => (UnownUnlocked & (1 << 3)) == 1 << 3;
        set => UnownUnlocked = (UnownUnlocked & ~(1 << 3)) | ((value ? 1 : 0) << 3);
    }

    /// <summary>
    /// Chooses which Unown sprite to show in the regular Pokédex View
    /// </summary>
    public int UnownFirstSeen
    {
        get => Data[Offsets.PokedexSeen + 0x1F + 28];
        set => Data[Offsets.PokedexSeen + 0x1F + 28] = (byte)value;
    }

    public override bool GetSeen(ushort species) => GetDexFlag(Offsets.PokedexSeen, species);
    public override bool GetCaught(ushort species) => GetDexFlag(Offsets.PokedexCaught, species);
    public override void SetSeen(ushort species, bool seen) => SetDexFlag(Offsets.PokedexSeen, species, seen);

    public override void SetCaught(ushort species, bool caught)
    {
        SetDexFlag(Offsets.PokedexCaught, species, caught);
        if (caught && species == (int)Species.Unown)
            SetUnownFormFlags();
    }

    private bool GetDexFlag(int region, ushort species)
    {
        int bit = species - 1;
        int ofs = bit >> 3;
        return GetFlag(region + ofs, bit & 7);
    }

    private void SetDexFlag(int region, ushort species, bool value)
    {
        int bit = species - 1;
        int ofs = bit >> 3;
        SetFlag(region + ofs, bit & 7, value);
    }

    public byte GetWork(int index) => Data[EventWork + index];
    public void SetWork(int index, byte value) => Data[EventWork + index] = value;
    public bool GetEventFlag(int flagNumber)
    {
        if ((uint)flagNumber >= EventFlagCount)
            throw new ArgumentOutOfRangeException(nameof(flagNumber), $"Event Flag to get ({flagNumber}) is greater than max ({EventFlagCount}).");
        return GetFlag(EventFlag + (flagNumber >> 3), flagNumber & 7);
    }

    public void SetEventFlag(int flagNumber, bool value)
    {
        if ((uint)flagNumber >= EventFlagCount)
            throw new ArgumentOutOfRangeException(nameof(flagNumber), $"Event Flag to set ({flagNumber}) is greater than max ({EventFlagCount}).");
        SetFlag(EventFlag + (flagNumber >> 3), flagNumber & 7, value);
    }

    // Misc
    public ushort ResetKey => GetResetKey();

    private ushort GetResetKey()
    {
        ushort result = 0;
        foreach (var b in Data.AsSpan(Offsets.Money, 3))
            result += b;
        var tr = Data.AsSpan(Offsets.Trainer1, 7);
        var end = tr[2..].IndexOf(StringConverter12.G1TerminatorCode);
        if (end >= 0)
            tr = tr[..(end + 2)];
        foreach (var b in tr)
            result += b;
        return result;
    }

    /// <summary>
    /// Sets the "Time Not Set" flag to the RTC Flag list.
    /// </summary>
    public void ResetRTC() => Data[Offsets.RTCFlags] |= 0x80;

    public void UnlockAllDecorations()
    {
        for (int i = 676; i <= 721; i++)
            SetEventFlag(i, true);
    }

    public override string GetString(ReadOnlySpan<byte> data)
    {
        if (Korean)
            return StringConverter2KOR.GetString(data);
        return StringConverter12.GetString(data, Japanese);
    }

    public override int SetString(Span<byte> destBuffer, ReadOnlySpan<char> value, int maxLength, StringConverterOption option)
    {
        if (Korean)
            return StringConverter2KOR.SetString(destBuffer, value, maxLength, option);
        return StringConverter12.SetString(destBuffer, value, maxLength, Japanese, option);
    }

    public bool IsGBMobileAvailable => Japanese && Version == GameVersion.C;
    public bool IsGBMobileEnabled => Japanese && Enum.IsDefined(typeof(GBMobileCableColor), GBMobileCable);

    public GBMobileCableColor GBMobileCable
    {
        get => (GBMobileCableColor) Data[0xE800];
        set
        {
            Data[0xE800] = (byte)value;
            Data[0x9000] = (byte)(0xFF - value);
        }
    }
}

public enum GBMobileCableColor : byte
{
    None = 0,
    Blue = 1,
    Yellow = 2,
    Green = 3,
    Red = 4,
    Purple = 5,
    Black = 6,
    Pink = 7,
    Gray = 8,
    Debug = 0x81,
    Disabled = 0xFF,
}