#nullable enable

using System.Collections.Generic;
using Demo2.Domain;
using Demo2.ECS;
using Unity.Collections;
using Unity.Entities;
using UnityEngine;

namespace Demo2.Runtime
{
    public sealed class Demo2MachineProxyPool : MonoBehaviour
    {
        [SerializeField] private Sprite[] machineSprites = new Sprite[8];
        private readonly Dictionary<int, SpriteRenderer> _active = new();
        private readonly Stack<SpriteRenderer> _pool = new();
        private readonly HashSet<int> _seen = new();
        private readonly List<int> _stale = new();

        public void SetSprites(Sprite[] sprites) => machineSprites = sprites;

        public void Refresh(Demo2EcsWorld? world)
        {
            if (world == null) { ReleaseAll(); return; }
            var manager = world.EntityManager;
            var query = manager.CreateEntityQuery(typeof(Demo2StableId), typeof(Demo2GridPosition), typeof(Demo2MachineState));
            using var entities = query.ToEntityArray(Allocator.Temp);
            using var ids = query.ToComponentDataArray<Demo2StableId>(Allocator.Temp);
            using var positions = query.ToComponentDataArray<Demo2GridPosition>(Allocator.Temp);
            _seen.Clear();
            for (var i = 0; i < entities.Length; i++)
            {
                var id = ids[i].Value;
                _seen.Add(id);
                if (!_active.TryGetValue(id, out var renderer))
                {
                    renderer = Acquire();
                    _active[id] = renderer;
                }
                var machine = manager.GetComponentData<Demo2MachineState>(entities[i]);
                renderer.name = $"MachineProxy_{id}_{machine.Kind}";
                renderer.transform.position = new Vector3(positions[i].X + 0.5f, Demo2Protocol.GridHeight - positions[i].Y - 0.5f, 0);
                renderer.transform.rotation = Quaternion.Euler(0, 0, -90f * machine.Rotation);
                renderer.transform.localScale = Vector3.one * 0.92f;
                renderer.sprite = SpriteFor(machine.Kind);
                renderer.color = machine.Faults > 0 ? new Color(1f, 0.52f, 0.42f) : Color.white;
            }
            _stale.Clear();
            foreach (var pair in _active) if (!_seen.Contains(pair.Key)) _stale.Add(pair.Key);
            foreach (var id in _stale) { Release(_active[id]); _active.Remove(id); }
        }

        private SpriteRenderer Acquire()
        {
            if (_pool.Count > 0) { var reused = _pool.Pop(); reused.gameObject.SetActive(true); return reused; }
            var go = new GameObject("MachineProxy");
            go.transform.SetParent(transform, false);
            var renderer = go.AddComponent<SpriteRenderer>();
            renderer.sortingOrder = 5;
            return renderer;
        }

        private void Release(SpriteRenderer renderer) { renderer.gameObject.SetActive(false); _pool.Push(renderer); }
        private void ReleaseAll() { foreach (var renderer in _active.Values) Release(renderer); _active.Clear(); }

        private Sprite? SpriteFor(Demo2MachineKind kind)
        {
            var index = kind == Demo2MachineKind.NightShiftSmelter ? (int)Demo2MachineKind.Smelter : (int)kind;
            return index >= 0 && index < machineSprites.Length ? machineSprites[index] : null;
        }
    }
}