using System;
using System.Collections.Generic;
using System.Linq;

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

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

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

        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 object Content => PK;

        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 => BitConverter.ToUInt16(Data, 0x4); set => BitConverter.GetBytes((ushort)value).CopyTo(Data, 0x4); }

        public PK4 PK
        {
            get => _pk ??= new PK4(Data.Slice(8, PokeCrypto.SIZE_4PARTY));
            set
            {
                _pk = value;
                var data = value.Data.All(z => z == 0)
                    ? value.Data
                    : PokeCrypto.EncryptArray45(value.Data);
                data.CopyTo(Data, 8);
            }
        }

        public override byte[] Write()
        {
            // Ensure PGT content is encrypted
            var clone = (PGT)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 (!IsPokémon || BitConverter.ToUInt32(Data, 0x64 + 8) != 0)
                return false;
            EncryptPK();
            return true;
        }

        private void EncryptPK()
        {
            byte[] ekdata = new byte[PokeCrypto.SIZE_4PARTY];
            Array.Copy(Data, 8, ekdata, 0, ekdata.Length);
            ekdata = PokeCrypto.EncryptArray45(ekdata);
            ekdata.CopyTo(Data, 8);
        }

        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 == GiftType.Pokémon || PGTGiftType == GiftType.PokémonEgg || PGTGiftType == 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.AltForm; set => PK.AltForm = 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 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 PK4((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);

            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)
        {
            // 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)Ability.Hydration;
            pk4.FatefulEncounter = true;
            pk4.Ball = (int)Core.Ball.Poke;
            pk4.Version = (int)GameVersion.D;
            pk4.Language = (int)LanguageID.English;
            pk4.Egg_Location = 1; // Ranger (will be +3000 later)
        }

        private void SetPINGA(PK4 pk4, EncounterCriteria criteria)
        {
            // Ability is forced already, can't force anything
            // todo: loop force the Nature/Gender

            // Generate IV
            uint seed = Util.Rand32();
            if (pk4.PID == 1 || IsManaphyEgg) // Create Nonshiny
                seed = GeneratePID(seed, pk4);

            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 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, Format);
            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 == Locations.LinkTrade4 || egg == 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 == Locations.LinkTrade4 || met == 0;
        }

        protected override bool IsMatchExact(PKM pkm, DexLevel evo) => false;
        protected override bool IsMatchDeferred(PKM pkm) => false;
    }
}