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

namespace PKHeX.Core
{
    /// <summary>
    /// <see cref="SaveFile"/> format for <see cref="GameVersion.HGSS"/>
    /// </summary>
    public sealed class SAV4HGSS : SAV4
    {
        public SAV4HGSS() : base(GeneralSize, StorageSize)
        {
            Initialize();
            Dex = new Zukan4(this, PokeDex);
        }

        public SAV4HGSS(byte[] data) : base(data, GeneralSize, StorageSize, GeneralSize + GeneralGap)
        {
            Initialize();
            Dex = new Zukan4(this, PokeDex);
        }

        public override Zukan4 Dex { get; }
        protected override SAV4 CloneInternal4() => State.Exportable ? new SAV4HGSS((byte[])Data.Clone()) : new SAV4HGSS();

        public override PersonalTable Personal => PersonalTable.HGSS;
        public override IReadOnlyList<ushort> HeldItems => Legal.HeldItems_HGSS;
        public override int MaxItemID => Legal.MaxItemID_4_HGSS;
        private const int GeneralSize = 0xF628;
        private const int StorageSize = 0x12310; // Start 0xF700, +0 starts box data
        private const int GeneralGap = 0xD8;
        protected override int StorageStart => 0xF700; // unused section right after GeneralSize, alignment?
        protected override int FooterSize => 0x10;

        private void Initialize()
        {
            Version = GameVersion.HGSS;
            GetSAVOffsets();
        }

        private void GetSAVOffsets()
        {
            AdventureInfo = 0;
            Trainer1 = 0x64;
            Party = 0x98;
            PokeDex = 0x12B8;
            WondercardFlags = 0x9D3C;
            WondercardData = 0x9E3C;

            EventConst = 0xDE4;
            EventFlag = 0x10C4;
            DaycareOffset = 0x15FC;
            Seal = 0x4E20;

            Box = 0;
        }

        #region Storage
        // box{pk4[30}[18]
        // u32 currentBox
        // u32 counter
        // g4str[18] boxNames
        // byte[18] boxWallpapers
        // -- each box is chunked, padded to nearest 0x100 (resulting in 0x10 trailing zeroes)
        // -- The final 0x16 bytes in the Storage block are unused (padding to nearest 0x100).
        private const int BOX_COUNT = 18;
        private const int BOX_SLOTS = 30;
        private const int BOX_NAME_LEN = 40; // 20 characters

        private const int BOX_DATA_LEN = (BOX_SLOTS * PokeCrypto.SIZE_4STORED) + 0x10; // 0xFF0, each box chunk is padded to nearest 0x100
        private const int BOX_END = BOX_COUNT * BOX_DATA_LEN; // 18 * 0x1000
        private const int BOX_NAME = 0x12008; // after current & counter
        private const int BOX_WP = BOX_NAME + (BOX_COUNT * BOX_NAME_LEN); // 0x122D8;
        private const int BOX_FLAGS = 18 + BOX_WP; // 0x122EA;

        public override int GetBoxOffset(int box) => box * 0x1000;
        private static int GetBoxNameOffset(int box) => BOX_NAME + (box * BOX_NAME_LEN);
        protected override int GetBoxWallpaperOffset(int box) => BOX_WP + box;

        // 8 bytes current box (align 32) & (stored count?)
        public override int CurrentBox
        {
            get => Storage[BOX_END];
            set => Storage[BOX_END] = (byte)value;
        }

        public override byte[] BoxFlags
        {
            get => new[] { Storage[BOX_FLAGS] };
            set => Storage[BOX_FLAGS] = value[0];
        }

        public int Counter
        {
            get => ReadInt32LittleEndian(Storage.AsSpan(BOX_END + 4));
            set => WriteInt32LittleEndian(Storage.AsSpan(BOX_END + 4), value);
        }

        public override string GetBoxName(int box) => GetString(Storage.AsSpan(GetBoxNameOffset(box), BOX_NAME_LEN));

        public override void SetBoxName(int box, string value)
        {
            const int maxlen = 8;
            var span = Storage.AsSpan(GetBoxNameOffset(box), BOX_NAME_LEN);
            SetString(span, value.AsSpan(), maxlen, StringConverterOption.ClearZero);
        }

        private static int AdjustWallpaper(int value, int shift)
        {
            // Pt's  Special Wallpapers 1-8 are shifted by +0x8
            // HG/SS Special Wallpapers 1-8 (Primo Phrases) are shifted by +0x10
            if (value >= 0x10) // special
                return value + shift;
            return value;
        }

        public override int GetBoxWallpaper(int box)
        {
            int offset = GetBoxWallpaperOffset(box);
            int value = Storage[offset];
            return AdjustWallpaper(value, -0x10);
        }

        public override void SetBoxWallpaper(int box, int value)
        {
            value = AdjustWallpaper(value, 0x10);
            Storage[GetBoxWallpaperOffset(box)] = (byte)value;
        }
        #endregion

        public override IReadOnlyList<InventoryPouch> Inventory
        {
            get
            {
                InventoryPouch[] pouch =
                {
                    new InventoryPouch4(InventoryType.Items, Legal.Pouch_Items_HGSS, 999, 0x644), // 0x644-0x8D7 (0x8CB)
                    new InventoryPouch4(InventoryType.KeyItems, Legal.Pouch_Key_HGSS, 1, 0x8D8), // 0x8D8-0x99F (0x979)
                    new InventoryPouch4(InventoryType.TMHMs, Legal.Pouch_TMHM_HGSS, 99, 0x9A0), // 0x9A0-0xB33 (0xB2F)
                    new InventoryPouch4(InventoryType.MailItems, Legal.Pouch_Mail_HGSS, 999, 0xB34), // 0xB34-0xB63 (0xB63)
                    new InventoryPouch4(InventoryType.Medicine, Legal.Pouch_Medicine_HGSS, 999, 0xB64), // 0xB64-0xC03 (0xBFB)
                    new InventoryPouch4(InventoryType.Berries, Legal.Pouch_Berries_HGSS, 999, 0xC04), // 0xC04-0xD03
                    new InventoryPouch4(InventoryType.Balls, Legal.Pouch_Ball_HGSS, 999, 0xD04), // 0xD04-0xD63
                    new InventoryPouch4(InventoryType.BattleItems, Legal.Pouch_Battle_HGSS, 999, 0xD64), // 0xD64-0xD97
                };
                return pouch.LoadAll(General);
            }
            set => value.SaveAll(General);
        }

        public override int M { get => ReadUInt16LittleEndian(General.AsSpan(0x1234)); set => WriteUInt16LittleEndian(General.AsSpan(0x1234), (ushort)value); }
        public override int X { get => ReadUInt16LittleEndian(General.AsSpan(0x123C)); set => WriteUInt16LittleEndian(General.AsSpan(0x123C), (ushort)(X2 = value)); }
        public override int Y { get => ReadUInt16LittleEndian(General.AsSpan(0x1240)); set => WriteUInt16LittleEndian(General.AsSpan(0x1240), (ushort)(Y2 = value)); }

        public override Span<byte> Rival_Trash
        {
            get => General.AsSpan(0x22D4, OTLength * 2);
            set { if (value.Length == OTLength * 2) value.CopyTo(General.AsSpan(0x22D4)); }
        }

        public override int X2 { get => ReadUInt16LittleEndian(General.AsSpan(0x236E)); set => WriteUInt16LittleEndian(General.AsSpan(0x236E), (ushort)value); }
        public override int Y2 { get => ReadUInt16LittleEndian(General.AsSpan(0x2372)); set => WriteUInt16LittleEndian(General.AsSpan(0x2372), (ushort)value); }
        public override int Z  { get => ReadUInt16LittleEndian(General.AsSpan(0x2376)); set => WriteUInt16LittleEndian(General.AsSpan(0x2376), (ushort)value); }

        public int Badges16
        {
            get => General[Trainer1 + 0x1F];
            set => General[Trainer1 + 0x1F] = (byte)value;
        }

        private const int OFS_GearRolodex = 0xC0EC;
        private const byte GearMaxCallers = (byte)(PokegearNumber.Ernest + 1);

        public PokegearNumber GetCallerAtIndex(int index) => (PokegearNumber)General[OFS_GearRolodex + index];
        public void SetCallerAtIndex(int index, PokegearNumber caller) => General[OFS_GearRolodex + index] = (byte)caller;

        public PokegearNumber[] GetPokeGearRoloDex()
        {
            var arr = General.AsSpan(OFS_GearRolodex, GearMaxCallers);
            return MemoryMarshal.Cast<byte, PokegearNumber>(arr).ToArray();
        }

        public void SetPokeGearRoloDex(ReadOnlySpan<PokegearNumber> value)
        {
            if (value.Length > GearMaxCallers)
                throw new ArgumentOutOfRangeException(nameof(value));
            MemoryMarshal.Cast<PokegearNumber, byte>(value).CopyTo(General.AsSpan(OFS_GearRolodex, GearMaxCallers));
        }

        public void PokeGearUnlockAllCallers()
        {
            for (int i = 0; i < GearMaxCallers; i++)
                SetCallerAtIndex(i, (PokegearNumber)i);
        }

        public void PokeGearClearAllCallers(int start = 0)
        {
            for (int i = start; i < GearMaxCallers; i++)
                SetCallerAtIndex(i, PokegearNumber.None);
        }

        public void PokeGearUnlockAllCallersNoTrainers()
        {
            var nonTrainers = new[]
            {
                PokegearNumber.Mother,
                PokegearNumber.Professor_Elm,
                PokegearNumber.Professor_Oak,
                PokegearNumber.Ethan,
                PokegearNumber.Lyra,
                PokegearNumber.Kurt,
                PokegearNumber.Daycare_Man,
                PokegearNumber.Daycare_Lady,
                PokegearNumber.Bill,
                PokegearNumber.Bike_Shop,
                PokegearNumber.Baoba,
            };
            for (int i = 0; i < nonTrainers.Length; i++)
                SetCallerAtIndex(i, nonTrainers[i]);

            // clear remaining callers
            PokeGearClearAllCallers(nonTrainers.Length);
        }

        // Apricorn Pouch
        public int GetApricornCount(int index) => General[0xE558 + index];
        public void SetApricornCount(int index, int count) => General[0xE558 + index] = (byte)count;

        // Pokewalker
        public const int WalkerPair = 0xE5E0;
        private const int OFS_WALKER = 0xE704;

        public uint PokewalkerSteps { get => ReadUInt32LittleEndian(General.AsSpan(OFS_WALKER)); set => WriteUInt32LittleEndian(General.AsSpan(OFS_WALKER), value); }
        public uint PokewalkerWatts { get => ReadUInt32LittleEndian(General.AsSpan(OFS_WALKER + 0x4)); set => WriteUInt32LittleEndian(General.AsSpan(OFS_WALKER + 4), value); }

        public bool[] GetPokewalkerCoursesUnlocked() => ArrayUtil.GitBitFlagArray(General.AsSpan(OFS_WALKER + 0x8), 32);
        public void SetPokewalkerCoursesUnlocked(bool[] value) => ArrayUtil.SetBitFlagArray(General.AsSpan(OFS_WALKER + 0x8), value);

        public void PokewalkerCoursesSetAll(uint value = 0x07FF_FFFFu) => WriteUInt32LittleEndian(General.AsSpan(OFS_WALKER + 0x8), value);

        public override uint SwarmSeed { get => ReadUInt32LittleEndian(General.AsSpan(0x68A8)); set => WriteUInt32LittleEndian(General.AsSpan(0x68A8), value); }
        public override uint SwarmMaxCountModulo => 20;
    }
}