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

namespace PKHeX.Core
{
    /// <summary>
    /// Generation 7 <see cref="SaveFile"/> object that reads from Pokémon Bank savedata (stored on AWS).
    /// </summary>
    public sealed class Bank7 : BulkStorage
    {
        public Bank7(byte[] data, Type t, int start, int slotsPerBox = 30) : base(data, t, start, slotsPerBox) => Version = GameVersion.USUM;

        public override PersonalTable Personal => PersonalTable.USUM;
        public override IReadOnlyList<ushort> HeldItems => Legal.HeldItems_SM;
        protected override SaveFile CloneInternal() => new Bank7((byte[])Data.Clone(), PKMType, BoxStart, SlotsPerBox);
        public override string PlayTimeString => $"{Year:00}{Month:00}{Day:00}_{Hours:00}ː{Minutes:00}";
        protected internal override string ShortSummary => PlayTimeString;
        private const int GroupNameSize = 0x20;
        private const int BankNameSize = 0x24;
        private const int GroupNameSpacing = GroupNameSize + 2;
        private const int BankNameSpacing = BankNameSize + 2;

        public ulong UID => ReadUInt64LittleEndian(Data.AsSpan(0));

        public string GetGroupName(int group)
        {
            if ((uint)group > 10)
                throw new ArgumentOutOfRangeException(nameof(group), $"{nameof(group)} must be 0-10.");
            int offset = 0x8 + (GroupNameSpacing * group) + 2; // skip over " "
            return GetString(offset, GroupNameSize / 2);
        }

        public override int BoxCount => BankCount;

        private int BankCount
        {
            get => Data[0x15E];
            set => Data[0x15E] = (byte)value;
        }

        private int Year => ReadUInt16LittleEndian(Data.AsSpan(0x160));
        private int Month => Data[0x162];
        private int Day => Data[0x163];
        private int Hours => Data[0x164];
        private int Minutes => Data[0x165];

        private int BoxDataSize => (SlotsPerBox * SIZE_STORED) + BankNameSpacing;
        public override int GetBoxOffset(int box) => Box + (BoxDataSize * box);
        public override string GetBoxName(int box) => GetString(GetBoxNameOffset(box), BankNameSize / 2);
        public int GetBoxNameOffset(int box) => GetBoxOffset(box) + (SlotsPerBox * SIZE_STORED);
        public int GetBoxIndex(int box) => ReadUInt16LittleEndian(Data.AsSpan(GetBoxNameOffset(box) + BankNameSize));

        private const int BoxStart = 0x17C;
        public static Bank7 GetBank7(byte[] data) => new(data, typeof(PK7), BoxStart);
    }
}
