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

namespace PKHeX.Core
{
    /// <summary>
    /// Generation 4 Mystery Gift Template File (Inner Gift Data, no card data)
    /// </summary>
    public sealed class PGT : DataMysteryGift, IRibbonSetEvent3, IRibbonSetEvent4
    {
        public const int Size = 0x104; // 260
        public override int Generation => 4;

        public override byte Level
        {
            get => IsManaphyEgg ? (byte)1 : IsPokémon ? (byte)PK.Met_Level : (byte)0;
            set { if (IsPokémon) PK.Met_Level = value; }
        }

        public override int Ball
        {
            get => IsPokémon ? PK.Ball : 0;
            set { if (IsPokémon) PK.Ball = value; }
        }

        public override AbilityPermission Ability => IsManaphyEgg ? AbilityPermission.Any12 : (int)(PK.PID & 1) == 1 ? AbilityPermission.OnlySecond : AbilityPermission.OnlyFirst;

        private enum GiftType
        {
            Pokémon = 1,
            PokémonEgg = 2,
            Item = 3,
            Rule = 4,
            Seal = 5,
            Accessory = 6,
            ManaphyEgg = 7,
            MemberCard = 8,
            OaksLetter = 9,
            AzureFlute = 10,
            PokétchApp = 11,
            Ribbon = 12,
            PokéWalkerArea = 14,
        }

        public override string CardTitle { get => "Raw Gift (PGT)"; set { } }
        public override int CardID { get => -1; set { } }
        public override bool GiftUsed { get => false; set { } }
        public override Shiny Shiny => IsEgg ? Shiny.Random : PK.PID == 1 ? Shiny.Never : IsShiny ? Shiny.Always : Shiny.Never;

        public PGT() : this(new byte[Size]) { }
        public PGT(byte[] data) : base(data) { }

        public byte CardType { get => Data[0]; set => Data[0] = value; }
        // Unused 0x01
        public byte Slot { get => Data[2]; set => Data[2] = value; }
        public byte Detail { get => Data[3]; set => Data[3] = value; }
        public override int ItemID { get => ReadUInt16LittleEndian(Data.AsSpan(0x4)); set => WriteUInt16LittleEndian(Data.AsSpan(0x4), (ushort)value); }

        public PK4 PK
        {
            get => _pk ??= new PK4(Data.Slice(8, PokeCrypto.SIZE_4PARTY));
            set
            {
                _pk = value;
                var data = Array.FindIndex(value.Data, z => z != 0) == -1 // all zero
                    ? value.Data
                    : PokeCrypto.EncryptArray45(value.Data);
                data.CopyTo(Data, 8);
            }
        }

        public override byte[] Write()
        {
            // Ensure PGT content is encrypted
            var clone = new PGT((byte[])Data.Clone());
            clone.VerifyPKEncryption();
            return clone.Data;
        }

        private PK4? _pk;

        /// <summary>
        /// Double checks the encryption of the gift data for Pokemon data.
        /// </summary>
        /// <returns>True if data was encrypted, false if the data was not modified.</returns>
        public bool VerifyPKEncryption()
        {
            if (PGTGiftType is not (GiftType.Pokémon or GiftType.PokémonEgg))
                return false; // not encrypted
            if (ReadUInt32LittleEndian(Data.AsSpan(0x64 + 8)) != 0)
                return false; // already encrypted (unused PK4 field, zero)
            EncryptPK();
            return true;
        }

        private void EncryptPK()
        {
            var span = Data.AsSpan(8, PokeCrypto.SIZE_4PARTY);
            var ekdata = PokeCrypto.EncryptArray45(span);
            ekdata.CopyTo(span);
        }

        private GiftType PGTGiftType { get => (GiftType)Data[0]; set => Data[0] = (byte)value; }
        public bool IsHatched => PGTGiftType == GiftType.Pokémon;
        public override bool IsEgg { get => PGTGiftType == GiftType.PokémonEgg || IsManaphyEgg; set { if (value) { PGTGiftType = GiftType.PokémonEgg; PK.IsEgg = true; } } }
        public bool IsManaphyEgg { get => PGTGiftType == GiftType.ManaphyEgg; set { if (value) PGTGiftType = GiftType.ManaphyEgg; } }
        public override bool EggEncounter => IsEgg;
        public override bool IsItem { get => PGTGiftType == GiftType.Item; set { if (value) PGTGiftType = GiftType.Item; } }
        public override bool IsPokémon { get => PGTGiftType is GiftType.Pokémon or GiftType.PokémonEgg or GiftType.ManaphyEgg; set { } }

        public override int Species { get => IsManaphyEgg ? 490 : PK.Species; set => PK.Species = value; }
        public override IReadOnlyList<int> Moves { get => PK.Moves; set => PK.SetMoves(value); }
        public override int HeldItem { get => PK.HeldItem; set => PK.HeldItem = value; }
        public override bool IsShiny => PK.IsShiny;
        public override int Gender { get => PK.Gender; set => PK.Gender = value; }
        public override int Form { get => PK.Form; set => PK.Form = value; }
        public override int TID { get => (ushort)PK.TID; set => PK.TID = value; }
        public override int SID { get => (ushort)PK.SID; set => PK.SID = value; }
        public override string OT_Name { get => PK.OT_Name; set => PK.OT_Name = value; }
        public override int Location { get => PK.Met_Location; set => PK.Met_Location = value; }
        public override int EggLocation { get => PK.Egg_Location; set => PK.Egg_Location = value; }
        public override bool HasFixedIVs => PK.IV32 != 0;
        public override void GetIVs(Span<int> value)
        {
            if (HasFixedIVs)
                PK.GetIVs(value);
        }

        public override PKM ConvertToPKM(ITrainerInfo sav, EncounterCriteria criteria)
        {
            if (!IsPokémon)
                throw new ArgumentException(nameof(IsPokémon));

            // template is already filled out, only minor mutations required
            PK4 pk4 = new((byte[])PK.Data.Clone()) { Sanity = 0 };
            if (!IsHatched && Detail == 0)
            {
                pk4.OT_Name = sav.OT;
                pk4.TID = sav.TID;
                pk4.SID = sav.SID;
                pk4.OT_Gender = sav.Gender;
                pk4.Language = sav.Language;
            }

            if (IsManaphyEgg)
                SetDefaultManaphyEggDetails(pk4, sav);

            SetPINGA(pk4, criteria);
            SetMetData(pk4, sav);

            var pi = pk4.PersonalInfo;
            pk4.CurrentFriendship = pk4.IsEgg ? pi.HatchCycles : pi.BaseFriendship;

            pk4.RefreshChecksum();
            return pk4;
        }

        private void SetMetData(PK4 pk4, ITrainerInfo trainer)
        {
            if (!EggEncounter)
            {
                pk4.Met_Location = pk4.Egg_Location + 3000;
                pk4.Egg_Location = 0;
                pk4.MetDate = DateTime.Now;
                pk4.IsEgg = false;
            }
            else
            {
                pk4.Egg_Location += 3000;
                if (trainer.Generation == 4)
                    SetUnhatchedEggDetails(pk4);
                else
                    SetHatchedEggDetails(pk4);
            }
        }

        private static void SetDefaultManaphyEggDetails(PK4 pk4, ITrainerInfo trainer)
        {
            // Since none of this data is populated, fill in default info.
            pk4.Species = (int)Core.Species.Manaphy;
            pk4.Gender = 2;
            // Level 1 Moves
            pk4.Move1 = 294; pk4.Move1_PP = 20;
            pk4.Move2 = 145; pk4.Move2_PP = 30;
            pk4.Move3 = 346; pk4.Move3_PP = 15;
            pk4.Ability = (int)Core.Ability.Hydration;
            pk4.FatefulEncounter = true;
            pk4.Ball = (int)Core.Ball.Poke;
            pk4.Version = GameVersion.Gen4.Contains(trainer.Game) ? trainer.Game : (int)GameVersion.D;
            var lang = trainer.Language < (int)LanguageID.Korean ? trainer.Language : (int)LanguageID.English;
            pk4.Language = lang;
            pk4.Egg_Location = 1; // Ranger (will be +3000 later)
            pk4.Nickname = SpeciesName.GetSpeciesNameGeneration((int)Core.Species.Manaphy, lang, 4);
        }

        private void SetPINGA(PK4 pk4, EncounterCriteria criteria)
        {
            // Ability is forced already, can't force anything

            // Generate PID
            var seed = SetPID(pk4, criteria);

            if (!IsManaphyEgg)
                seed = Util.Rand32(); // reseed, do not have method 1 correlation

            // Generate IVs
            if (pk4.IV32 == 0) // Ignore Nickname/Egg flag bits; none are set for varied-IV gifts.
            {
                uint iv1 = ((seed = RNG.LCRNG.Next(seed)) >> 16) & 0x7FFF;
                uint iv2 = ((RNG.LCRNG.Next(seed)) >> 16) & 0x7FFF;
                pk4.IV32 = iv1 | iv2 << 15;
            }
        }

        private uint SetPID(PK4 pk4, EncounterCriteria criteria)
        {
            uint seed = Util.Rand32();
            if (pk4.PID != 1 && !IsManaphyEgg)
                return seed; // PID is already set.

            // The games don't decide the Nature/Gender up-front, but we can try to honor requests.
            // Pre-determine the result values, and generate something.
            var n = (int)criteria.GetNature(Nature.Random);
            // Gender is already pre-determined in the template.
            while (true)
            {
                seed = GeneratePID(seed, pk4);
                if (pk4.Nature != n)
                    continue;
                return seed;
            }
        }

        private static void SetHatchedEggDetails(PK4 pk4)
        {
            pk4.IsEgg = false;
            // Met Location & Date is modified when transferred to pk5; don't worry about it.
            pk4.EggMetDate = DateTime.Now;
        }

        private void SetUnhatchedEggDetails(PK4 pk4)
        {
            pk4.IsEgg = true;
            pk4.IsNicknamed = false;
            pk4.Nickname = SpeciesName.GetSpeciesNameGeneration(0, pk4.Language, Generation);
            pk4.EggMetDate = DateTime.Now;
        }

        private static uint GeneratePID(uint seed, PK4 pk4)
        {
            do
            {
                uint pid1 = (seed = RNG.LCRNG.Next(seed)) >> 16; // low
                uint pid2 = (seed = RNG.LCRNG.Next(seed)) & 0xFFFF0000; // hi
                pk4.PID = pid2 | pid1;
                // sanity check gender for non-genderless PID cases
            } while (!pk4.IsGenderValid());

            while (pk4.IsShiny) // Call the ARNG to change the PID
                pk4.PID = RNG.ARNG.Next(pk4.PID);
            return seed;
        }

        public static bool IsRangerManaphy(PKM pkm)
        {
            var egg = pkm.Egg_Location;
            if (!pkm.IsEgg) // Link Trade Egg or Ranger
                return egg is Locations.LinkTrade4 or Locations.Ranger4;
            if (egg != Locations.Ranger4)
                return false;

            if (pkm.Language == (int)LanguageID.Korean) // never korean
                return false;

            var met = pkm.Met_Location;
            return met is Locations.LinkTrade4 or 0;
        }

        // Nothing is stored as a PGT besides Ranger Manaphy. Nothing should trigger these.
        public override bool IsMatchExact(PKM pkm, IDexLevel evo) => false;
        protected override bool IsMatchDeferred(PKM pkm) => false;
        protected override bool IsMatchPartial(PKM pkm) => false;

        public bool RibbonEarth { get => PK.RibbonEarth; set => PK.RibbonEarth = value; }
        public bool RibbonNational { get => PK.RibbonNational; set => PK.RibbonNational = value; }
        public bool RibbonCountry { get => PK.RibbonCountry; set => PK.RibbonCountry = value; }
        public bool RibbonChampionBattle { get => PK.RibbonChampionBattle; set => PK.RibbonChampionBattle = value; }
        public bool RibbonChampionRegional { get => PK.RibbonChampionRegional; set => PK.RibbonChampionRegional = value; }
        public bool RibbonChampionNational { get => PK.RibbonChampionNational; set => PK.RibbonChampionNational = value; }
        public bool RibbonClassic { get => PK.RibbonClassic; set => PK.RibbonClassic = value; }
        public bool RibbonWishing { get => PK.RibbonWishing; set => PK.RibbonWishing = value; }
        public bool RibbonPremier { get => PK.RibbonPremier; set => PK.RibbonPremier = value; }
        public bool RibbonEvent { get => PK.RibbonEvent; set => PK.RibbonEvent = value; }
        public bool RibbonBirthday { get => PK.RibbonBirthday; set => PK.RibbonBirthday = value; }
        public bool RibbonSpecial { get => PK.RibbonSpecial; set => PK.RibbonSpecial = value; }
        public bool RibbonWorld { get => PK.RibbonWorld; set => PK.RibbonWorld = value; }
        public bool RibbonChampionWorld { get => PK.RibbonChampionWorld; set => PK.RibbonChampionWorld = value; }
        public bool RibbonSouvenir { get => PK.RibbonSouvenir; set => PK.RibbonSouvenir = value; }
    }
}