using System;
using System.Linq;
using pkNX.Structures;

namespace pkNX.Randomization;

public class SpeciesRandomizer
{
    private readonly IPersonalTable SpeciesStat;
    private readonly int MaxSpeciesID;
    private readonly GameInfo Game;

    private SpeciesSettings s = new();

    public SpeciesRandomizer(GameInfo game, IPersonalTable t)
    {
        Game = game;
        MaxSpeciesID = Game.MaxSpeciesID;
        SpeciesStat = t;
    }

    /// <summary>
    /// Initializes the <see cref="RandSpec"/> according to the provided settings.
    /// </summary>
    /// <param name="settings">General settings</param>
    /// <param name="banlist">Optional extra: banned species</param>
    public void Initialize(SpeciesSettings settings, params int[] banlist)
    {
        s = settings;
        var list = s.GetSpecies(Game.MaxSpeciesID, Game.Generation).Except(banlist);

        legends = Game.Generation == 8 ? Legal.Legendary_8 : Legal.Legendary_1;
        events = Game.Generation == 8 ? Legal.Mythical_8 : Legal.Mythical_GG;

        RandSpec = new GenericRandomizer<int>(list.ToArray());
        RandLegend = new GenericRandomizer<int>(legends.Except(banlist).ToArray());
        RandEvent = new GenericRandomizer<int>(events.Except(banlist).ToArray());
    }

    #region Random Species Filtering Parameters
    private GenericRandomizer<int> RandSpec = new(Array.Empty<int>());
    private GenericRandomizer<int> RandLegend = new(Array.Empty<int>());
    private GenericRandomizer<int> RandEvent = new(Array.Empty<int>());
    private int[] legends = Array.Empty<int>();
    private int[] events = Array.Empty<int>();
    private int loopctr;
    private const int l = 10; // tweakable scalars
    private const int h = 11;
    #endregion

    internal int GetRandomSpecies(int oldSpecies, params int[] bannedSpecies)
    {
        // Get a new random species
        var oldpkm = SpeciesStat[oldSpecies];

        loopctr = 0; // altering calculations to prevent infinite loops
        int newSpecies;
        while (!GetNewSpecies(oldSpecies, oldpkm, out newSpecies) || bannedSpecies.Contains(newSpecies))
            loopctr++;
        return newSpecies;
    }

    public int GetRandomSpeciesType(int oldSpecies, int type)
    {
        // Get a new random species
        IPersonalInfo oldpkm = SpeciesStat[oldSpecies];

        loopctr = 0; // altering calculations to prevent infinite loops
        int newSpecies;
        while (!GetNewSpecies(oldSpecies, oldpkm, out newSpecies) || !GetIsTypeMatch(newSpecies, type))
            loopctr++;
        return newSpecies;
    }

    private bool GetIsTypeMatch(int newSpecies, int type) => type == -1 || SpeciesStat[newSpecies].IsType((Types)type) || loopctr > 9000;

    public int GetRandomSpecies() => RandSpec.Next();

    public int GetRandomSpecies(int oldSpecies)
    {
        // Get a new random species
        var oldpkm = SpeciesStat[oldSpecies];

        loopctr = 0; // altering calculations to prevent infinite loops
        int newSpecies;
        while (!GetNewSpecies(oldSpecies, oldpkm, out newSpecies))
        {
            if (loopctr > 0x0001_0000)
            {
                var pkm = SpeciesStat[newSpecies];
                if (IsSpeciesBSTBad(oldpkm, pkm) && loopctr > 0x0001_1000) // keep trying for at minimum BST
                    continue;
                return newSpecies; // failed to find any match based on criteria, return random species that may or may not match criteria
            }
            loopctr++;
        }
        return newSpecies;
    }

    public int[] RandomSpeciesList => Enumerable.Range(1, MaxSpeciesID).ToArray();

    private bool GetNewSpecies(int currentSpecies, IPersonalInfo oldpkm, out int newSpecies)
    {
        bool isLegend = false;

        newSpecies = RandSpec.Next();

        // If we randomly got a legendary or mythical, not really a need to reroll
        if (legends.Contains(newSpecies) || events.Contains(newSpecies)) isLegend = true;

        if ((Util.Random.Next(0, 100 + 1) < s.LegendsChance) && s.Legends)
        {
            if (!isLegend) newSpecies = RandLegend.Next();
            isLegend = true;
        }

        if ((Util.Random.Next(0, 100 + 1) < s.EventsChance) && s.Events)
        {
            if (!isLegend) newSpecies = RandEvent.Next();
        }

        var pkm = SpeciesStat[newSpecies];

        if (IsSpeciesReplacementBad(newSpecies, currentSpecies)) // no A->A randomization
            return false;
        return IsCriteriaMatch(oldpkm, pkm);
    }

    private bool IsSpeciesReplacementBad(int newSpecies, int currentSpecies)
    {
        if (newSpecies != currentSpecies)
            return false;
        return loopctr < MaxSpeciesID * 10;
    }

    private bool IsCriteriaMatch(IPersonalInfo oldpkm, IPersonalInfo pkm)
    {
        if (IsSpeciesEXPRateBad(oldpkm, pkm))
            return false;
        if (IsSpeciesTypeBad(oldpkm, pkm))
            return false;
        if (IsSpeciesBSTBad(oldpkm, pkm))
            return false;
        return true;
    }

    private bool IsSpeciesEXPRateBad(IPersonalTraits oldpkm, IPersonalTraits pkm)
    {
        return s.EXPGroup && oldpkm.EXPGrowth == pkm.EXPGrowth;
    }

    private bool IsSpeciesTypeBad(IPersonalType oldpkm, IPersonalType pkm)
    {
        return s.Type && (oldpkm.IsType(pkm.Type1) || oldpkm.IsType(pkm.Type2));
    }

    private bool IsSpeciesBSTBad(IPersonalInfo oldpkm, IPersonalInfo pkm)
    {
        if (!s.BST)
            return false;

        // Base stat total has to be close to original BST
        int oldBST = oldpkm.GetBaseStatTotal();
        int pkmBST = pkm.GetBaseStatTotal();

        int expand = loopctr / MaxSpeciesID;
        int lo = oldBST * l / (h + expand);
        int hi = oldBST * (h + expand) / l;
        return lo > pkmBST || pkmBST > hi;
    }
}