using System.Collections.Generic;
using UnityEngine;

namespace ProjectI.Enemies
{
    public sealed class EnemyTargetSelection
    {
        public EnemyTargetKey? Selected { get; private set; }
#if UNITY_EDITOR || DEVELOPMENT_BUILD
        public string Reason { get; private set; } = "No eligible evidence";
#endif
        public double HoldUntil { get; private set; }
        private readonly double holdSeconds;
        public EnemyTargetSelection(double holdSeconds = 1.5) { this.holdSeconds = holdSeconds; }
        public void Clear(string reason = null)
        {
            Selected = null; HoldUntil = 0;
#if UNITY_EDITOR || DEVELOPMENT_BUILD
            Reason = reason ?? "No eligible evidence";
#endif
        }
        public bool Select(IReadOnlyList<EnemyObservationRules> memories, Vector3 origin, double now, out EnemyTargetKey target)
        {
            target = default;
            EnemyObservationRules best = null, incumbent = null;
            int bestQuality = -1, incumbentQuality = -1; float bestDistance = float.PositiveInfinity;
            foreach (var memory in memories)
            {
                if (!memory.TryBest(now, out var evidence, out int quality)) continue;
                float distance = (evidence.Position - origin).sqrMagnitude;
                if (Selected.HasValue && Selected.Value.Equals(memory.Key)) { incumbent = memory; incumbentQuality = quality; }
                if (quality > bestQuality || quality == bestQuality && (distance < bestDistance
                    || distance == bestDistance && (best == null || memory.Key.NetworkObjectId < best.Key.NetworkObjectId)))
                { best = memory; bestQuality = quality; bestDistance = distance; }
            }
            if (best == null) { Clear(); return false; }
            if (incumbent != null && now < HoldUntil && incumbentQuality == bestQuality)
            {
                target = incumbent.Key;
#if UNITY_EDITOR || DEVELOPMENT_BUILD
                Reason = "Holding equal-quality preference";
#endif
                return true;
            }
            target = best.Key;
            if (!Selected.HasValue || !Selected.Value.Equals(target))
            {
#if UNITY_EDITOR || DEVELOPMENT_BUILD
                Reason = incumbent != null && bestQuality > incumbentQuality ? "Better evidence" : "Best evidence, nearest known position";
#endif
                Selected = target; HoldUntil = now + holdSeconds;
            }
#if UNITY_EDITOR || DEVELOPMENT_BUILD
            else Reason = "Best evidence, nearest known position";
#endif
            return true;
        }
    }
}