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

namespace PKHeX.Core
{
    /// <summary> Generation 8 <see cref="PKM"/> format. </summary>
    public sealed class PK8 : G8PKM
    {
        private static readonly ushort[] Unused =
        {
            // Alignment bytes
            0x17, 0x1A, 0x1B, 0x23, 0x33, 0x3E, 0x3F,
            0x4C, 0x4D, 0x4E, 0x4F,
            0x52, 0x53, 0x54, 0x55, 0x56, 0x57,

            0x91, 0x92, 0x93,
            0x9C, 0x9D, 0x9E, 0x9F, 0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7,

            0xC5,
            0xCE, 0xCF, 0xD0, 0xD1, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB,
            0xE0, 0xE1, // Old Console Region / Region
            0xE9, 0xEA, 0xEB, 0xEC, 0xED, 0xEE, 0xEF, 0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7,
            0x115, 0x11F, // Alignment

            0x13D, 0x13E, 0x13F,
            0x140, 0x141, 0x142, 0x143, 0x144, 0x145, 0x146, 0x147,
        };

        public override IReadOnlyList<ushort> ExtraBytes => Unused;
        public override PersonalInfo PersonalInfo => PersonalTable.SWSH.GetFormEntry(Species, Form);

        public PK8() => AffixedRibbon = -1; // 00 would make it show Kalos Champion :)
        public PK8(byte[] data) : base(data) { }
        public override PKM Clone() => new PK8((byte[])Data.Clone());

        public void Trade(ITrainerInfo tr, int Day = 1, int Month = 1, int Year = 2015)
        {
            if (IsEgg)
            {
                // Eggs do not have any modifications done if they are traded
                // Apply link trade data, only if it left the OT (ignore if dumped & imported, or cloned, etc)
                if ((tr.OT != OT_Name) || (tr.TID != TID) || (tr.SID != SID) || (tr.Gender != OT_Gender))
                    SetLinkTradeEgg(Day, Month, Year, Locations.LinkTrade6);
                return;
            }

            // Process to the HT if the OT of the Pokémon does not match the SAV's OT info.
            if (!TradeOT(tr))
                TradeHT(tr);
        }

        public int DynamaxType { get => ReadUInt16LittleEndian(Data.AsSpan(0x156)); set => WriteUInt16LittleEndian(Data.AsSpan(0x156), (ushort)value); }

        public void FixMemories()
        {
            if (IsEgg) // No memories if is egg.
            {
                HT_Language = HT_Friendship = HT_TextVar = HT_Memory = HT_Intensity = HT_Feeling =
                /* OT_Friendship */ OT_TextVar = OT_Memory = OT_Intensity = OT_Feeling = 0;

                // Clear Handler
                HT_Trash.Clear();
                return;
            }

            if (IsUntraded)
                HT_Language = HT_Friendship = HT_TextVar = HT_Memory = HT_Intensity = HT_Feeling = 0;

            int gen = Generation;
            if (gen < 6)
                OT_TextVar = OT_Memory = OT_Intensity = OT_Feeling = 0;
            if (gen != 8) // must be transferred via HOME, and must have memories
                this.SetTradeMemoryHT8(); // not faking HOME tracker.
        }

        private bool TradeOT(ITrainerInfo tr)
        {
            // Check to see if the OT matches the SAV's OT info.
            if (!(tr.OT == OT_Name && tr.TID == TID && tr.SID == SID && tr.Gender == OT_Gender))
                return false;

            CurrentHandler = 0;
            return true;
        }

        private void TradeHT(ITrainerInfo tr)
        {
            if (HT_Name != tr.OT)
            {
                HT_Friendship = 50;
                HT_Name = tr.OT;
            }
            CurrentHandler = 1;
            HT_Gender = tr.Gender;
            HT_Language = tr.Language;
            this.SetTradeMemoryHT8();
        }

        // Maximums
        public override int MaxMoveID => Legal.MaxMoveID_8;
        public override int MaxSpeciesID => Legal.MaxSpeciesID_8;
        public override int MaxAbilityID => Legal.MaxAbilityID_8;
        public override int MaxItemID => Legal.MaxItemID_8;
        public override int MaxBallID => Legal.MaxBallID_8;
        public override int MaxGameID => Legal.MaxGameID_8;
    }
}