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

namespace PKHeX.Core
{
    public sealed class BoxLayout7 : SaveBlock<SAV7>, IBoxDetailName, IBoxDetailWallpaper, ITeamIndexSet
    {
        private const int BoxCount = 32;

        private const int BattleBoxFlags      = 0x4C4;
        private const int PCBackgrounds       = 0x5C0;
        private const int PCFlags             = 0x5E0;
        private const int Unlocked            = 0x5E1;
        private const int LastViewedBoxOffset = 0x5E3;

        private const int StringMaxLength = SAV6.LongStringLength / 2;

        private const int TeamCount = 6;
        private const int NONE_SELECTED = -1;
        public readonly int[] TeamSlots = new int[TeamCount * 6];

        public BoxLayout7(SAV7SM sav, int offset) : base(sav) => Offset = offset;
        public BoxLayout7(SAV7USUM sav, int offset) : base(sav) => Offset = offset;

        public int GetBoxWallpaperOffset(int box) => Offset + PCBackgrounds + box;

        public int GetBoxWallpaper(int box)
        {
            if ((uint)box > SAV.BoxCount)
                return 0;
            return Data[GetBoxWallpaperOffset(box)];
        }

        public void SetBoxWallpaper(int box, int value)
        {
            if ((uint)box > SAV.BoxCount)
                return;
            Data[GetBoxWallpaperOffset(box)] = (byte)value;
        }

        private Span<byte> GetBoxNameSpan(int box) => Data.AsSpan(GetBoxNameOffset(box), SAV6.LongStringLength);
        private int GetBoxNameOffset(int box) => Offset + (SAV6.LongStringLength * box);
        public string GetBoxName(int box) => SAV.GetString(GetBoxNameSpan(box));
        public void SetBoxName(int box, string value) => SAV.SetString(GetBoxNameSpan(box), value.AsSpan(), StringMaxLength, StringConverterOption.ClearZero);

        public byte[] BoxFlags
        {
            get => new[] { Data[Offset + PCFlags] }; // bits for wallpaper unlocks
            set
            {
                if (value.Length != 1)
                    return;
                Data[Offset + PCFlags] = value[0];
            }
        }

        public int BoxesUnlocked
        {
            get => Data[Offset + Unlocked];
            set
            {
                if (value > BoxCount)
                    value = BoxCount;
                Data[Offset + Unlocked] = (byte)value;
            }
        }

        public int CurrentBox { get => Data[Offset + LastViewedBoxOffset]; set => Data[Offset + LastViewedBoxOffset] = (byte)value; }

        public void LoadBattleTeams()
        {
            for (int i = 0; i < TeamCount * 6; i++)
            {
                short val = ReadInt16LittleEndian(Data.AsSpan(Offset + BattleBoxFlags + (i * 2)));
                if (val < 0)
                {
                    TeamSlots[i] = NONE_SELECTED;
                    continue;
                }

                int box = val >> 8;
                int slot = val & 0xFF;
                int index = (SAV.BoxSlotCount * box) + slot;
                TeamSlots[i] = index & 0xFFFF;
            }
        }

        public void ClearBattleTeams()
        {
            for (int i = 0; i < TeamSlots.Length; i++)
                TeamSlots[i] = NONE_SELECTED;
            for (int i = 0; i < TeamCount; i++)
                SetIsTeamLocked(i, false);
        }

        public void SaveBattleTeams()
        {
            var span = Data.AsSpan(Offset + BattleBoxFlags);
            for (int i = 0; i < TeamCount * 6; i++)
            {
                int index = TeamSlots[i];
                if (index < 0)
                {
                    WriteInt16LittleEndian(span[(i*2)..], (short)index);
                    continue;
                }

                SAV.GetBoxSlotFromIndex(index, out var box, out var slot);
                index = (box << 8) | slot;
                WriteInt16LittleEndian(span[(i * 2)..], (short)index);
            }
        }

        public void UnlockAllTeams()
        {
            for (int i = 0; i < TeamCount; i++)
                SetIsTeamLocked(i, false);
        }

        public bool GetIsTeamLocked(int team) => Data[Offset + PCBackgrounds - TeamCount - team] == 1;
        public void SetIsTeamLocked(int team, bool value) => Data[Offset + PCBackgrounds - TeamCount - team] = value ? (byte)1 : (byte)0;

        public string this[int i]
        {
            get => GetBoxName(i);
            set => SetBoxName(i, value);
        }
    }
}