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

namespace PKHeX.Core;

/// <summary>
/// <see cref="PersonalInfo"/> class with values from Generation 4 games.
/// </summary>
public sealed class PersonalInfo4 : PersonalInfo
{
    public const int SIZE = 0x2C;
    private readonly byte[] Data;

    public PersonalInfo4(byte[] data)
    {
        Data = data;
        // Unpack TMHM & Tutors
        TMHM = GetBits(Data.AsSpan(0x1C, 0x0D));
        //TypeTutors = Array.Empty<bool>(); // not stored in personal -- default value
    }

    public override byte[] Write()
    {
        SetBits(TMHM, Data.AsSpan(0x1C));
        return Data;
    }

    public override int HP { get => Data[0x00]; set => Data[0x00] = (byte)value; }
    public override int ATK { get => Data[0x01]; set => Data[0x01] = (byte)value; }
    public override int DEF { get => Data[0x02]; set => Data[0x02] = (byte)value; }
    public override int SPE { get => Data[0x03]; set => Data[0x03] = (byte)value; }
    public override int SPA { get => Data[0x04]; set => Data[0x04] = (byte)value; }
    public override int SPD { get => Data[0x05]; set => Data[0x05] = (byte)value; }
    public override int Type1 { get => Data[0x06]; set => Data[0x06] = (byte)value; }
    public override int Type2 { get => Data[0x07]; set => Data[0x07] = (byte)value; }
    public override int CatchRate { get => Data[0x08]; set => Data[0x08] = (byte)value; }
    public override int BaseEXP { get => Data[0x09]; set => Data[0x09] = (byte)value; }
    private int EVYield { get => ReadUInt16LittleEndian(Data.AsSpan(0x0A)); set => WriteUInt16LittleEndian(Data.AsSpan(0x0A), (ushort)value); }
    public override int EV_HP { get => (EVYield >> 0) & 0x3; set => EVYield = (EVYield & ~(0x3 << 0)) | ((value & 0x3) << 0); }
    public override int EV_ATK { get => (EVYield >> 2) & 0x3; set => EVYield = (EVYield & ~(0x3 << 2)) | ((value & 0x3) << 2); }
    public override int EV_DEF { get => (EVYield >> 4) & 0x3; set => EVYield = (EVYield & ~(0x3 << 4)) | ((value & 0x3) << 4); }
    public override int EV_SPE { get => (EVYield >> 6) & 0x3; set => EVYield = (EVYield & ~(0x3 << 6)) | ((value & 0x3) << 6); }
    public override int EV_SPA { get => (EVYield >> 8) & 0x3; set => EVYield = (EVYield & ~(0x3 << 8)) | ((value & 0x3) << 8); }
    public override int EV_SPD { get => (EVYield >> 10) & 0x3; set => EVYield = (EVYield & ~(0x3 << 10)) | ((value & 0x3) << 10); }
    public int Item1 { get => ReadInt16LittleEndian(Data.AsSpan(0xC)); set => WriteInt16LittleEndian(Data.AsSpan(0xC), (short)value); }
    public int Item2 { get => ReadInt16LittleEndian(Data.AsSpan(0xE)); set => WriteInt16LittleEndian(Data.AsSpan(0xE), (short)value); }
    public override int Gender { get => Data[0x10]; set => Data[0x10] = (byte)value; }
    public override int HatchCycles { get => Data[0x11]; set => Data[0x11] = (byte)value; }
    public override int BaseFriendship { get => Data[0x12]; set => Data[0x12] = (byte)value; }
    public override int EXPGrowth { get => Data[0x13]; set => Data[0x13] = (byte)value; }
    public override int EggGroup1 { get => Data[0x14]; set => Data[0x14] = (byte)value; }
    public override int EggGroup2 { get => Data[0x15]; set => Data[0x15] = (byte)value; }
    public int Ability1 { get => Data[0x16]; set => Data[0x16] = (byte)value; }
    public int Ability2 { get => Data[0x17]; set => Data[0x17] = (byte)value; }
    public override int EscapeRate { get => Data[0x18]; set => Data[0x18] = (byte)value; }
    public override int Color { get => Data[0x19] & 0x7F; set => Data[0x19] = (byte)((Data[0x19] & 0x80) | value); }
    public bool NoFlip { get => Data[0x19] >> 7 == 1; set => Data[0x19] = (byte)(Color | (value ? 0x80 : 0)); }

    public IReadOnlyList<int> Items
    {
        get => new[] { Item1, Item2 };
        set
        {
            if (value.Count != 2) return;
            Item1 = value[0];
            Item2 = value[1];
        }
    }

    public override IReadOnlyList<int> Abilities
    {
        get => new[] { Ability1, Ability2 };
        set
        {
            if (value.Count != 2) return;
            Ability1 = (byte)value[0];
            Ability2 = (byte)value[1];
        }
    }

    public override int GetAbilityIndex(int abilityID) => abilityID == Ability1 ? 0 : abilityID == Ability2 ? 1 : -1;
    public int GetAbility(bool second) => second && HasSecondAbility ? Ability2 : Ability1;

    public bool HasSecondAbility => Ability1 != Ability2;

    // Manually added attributes
    public override int FormCount { get => Data[0x29]; set {} }
    public override int FormStatsIndex { get => ReadUInt16LittleEndian(Data.AsSpan(0x2A)); set {} }
}