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

namespace PKHeX.Core
{
    /// <summary>
    /// Shadow Pokémon Encounter found in <see cref="GameVersion.CXD"/>
    /// </summary>
    /// <inheritdoc cref="EncounterStatic"/>
    public sealed record EncounterStaticShadow : EncounterStatic
    {
        public override int Generation => 3;

        /// <summary>
        /// Team Specification with required <see cref="Species"/>, <see cref="Nature"/> and Gender.
        /// </summary>
        public readonly TeamLock[] Locks;

        /// <summary>
        /// Initial Shadow Gauge value.
        /// </summary>
        public int Gauge { get; init; }

        /// <summary>
        /// Originates from the EReader scans (Japanese Only)
        /// </summary>
        public bool EReader => ReferenceEquals(IVs, EReaderEmpty);

        public static readonly IReadOnlyList<int> EReaderEmpty = new[] {0,0,0,0,0,0};

        public EncounterStaticShadow(GameVersion game, TeamLock[] locks) : base(game) => Locks = locks;
        public EncounterStaticShadow(GameVersion game) : this(game, Array.Empty<TeamLock>()) { }

        private static readonly int[] MirorBXDLocations =
        {
            090, // Rock
            091, // Oasis
            092, // Cave
            113, // Pyrite Town
            059, // Realgam Tower
        };

        protected override bool IsMatchEggLocation(PKM pkm)
        {
            return true; // transfer location verified later
        }

        protected override bool IsMatchLocation(PKM pkm)
        {
            if (pkm.Format != 3)
                return true; // transfer location verified later

            var met = pkm.Met_Location;
            if (Version == GameVersion.XD)
            {
                if (met == Location)
                    return true;
                return MirorBXDLocations.Contains(met);
            }

            return met == Location;
        }

        protected override bool IsMatchLevel(PKM pkm, DexLevel evo)
        {
            if (pkm.Format != 3) // Met Level lost on PK3=>PK4
                return Level <= evo.Level;

            return pkm.Met_Level == Level;
        }

        protected override void ApplyDetails(ITrainerInfo sav, EncounterCriteria criteria, PKM pk)
        {
            base.ApplyDetails(sav, criteria, pk);
            ((IRibbonSetEvent3)pk).RibbonNational = true;
        }

        protected override void SetPINGA(PKM pk, EncounterCriteria criteria)
        {
            var pi = pk.PersonalInfo;
            int gender = criteria.GetGender(-1, pi);
            int nature = (int)criteria.GetNature(Nature.Random);
            int ability = criteria.GetAbilityFromNumber(0, pi);

            // Ensure that any generated specimen has valid Shadow Locks
            // This can be kinda slow, depending on how many locks / how strict they are.
            // Cancel this operation if too many attempts are made to prevent infinite loops.
            int ctr = 0;
            const int max = 100_000;
            do
            {
                PIDGenerator.SetRandomWildPID(pk, 3, nature, ability, gender, PIDType.CXD);
                var pidiv = MethodFinder.Analyze(pk);
                var result = LockFinder.IsAllShadowLockValid(this, pidiv, pk);
                if (result)
                    break;
            }
            while (++ctr <= max);

#if DEBUG
            System.Diagnostics.Debug.Assert(ctr < 100_000);
#endif

            // E-Reader have all IVs == 0
            if (EReader)
            {
                for (int i = 0; i < IVs.Count; i++)
                    pk.SetIV(i, 0);
            }
        }
    }
}