using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using BaseGames.Core;
using BaseGames.Player;
using BaseGames.Core.Events;
using BaseGames.Core.Save;
using BaseGames.Skills;
using BaseGames.Feedback;

namespace BaseGames.Equipment
{
    /// <summary>
    /// 装备管理器（架构 09_ProgressionModule §6）。
    /// 挂在 Player 上，管理护符的装备/卸下及 Notch 容量。
    /// 实现 ISaveable 以持久化装备状态。
    /// </summary>
    public class EquipmentManager : MonoBehaviour, ISaveable, IEquipmentService
    {
        [Header("配置")]
        [SerializeField] private EquipmentConfigSO  _config;
        [SerializeField] private CharmCatalogSO      _charmCatalog;

        [Header("Event Channels")]
        [SerializeField] private CharmEventChannelSO _onCharmEquipped;
        [SerializeField] private CharmEventChannelSO _onCharmUnequipped;
        [SerializeField] private VoidEventChannelSO  _onEquipmentChanged;

        [Tooltip("AchievementManager 解锁授予凹槽成就时发布；订阅后调用 IncreaseNotches(1)。")]
        [SerializeField] private VoidEventChannelSO  _onAchievementNotchGranted;

        private readonly List<CharmSO> _equipped  = new(4);
        private readonly List<CharmSO> _collected = new(32);
        private int _currentNotchCapacity;
        private int _usedNotches;

        private EquipmentContext _ctx;
        private readonly CompositeDisposable _subs = new();

        // ── 生命周期 ──────────────────────────────────────────────────────────
        private void OnEnable()
        {
            ServiceLocator.Register<IEquipmentService>(this);
            ServiceLocator.GetOrDefault<ISaveableRegistry>()?.Register(this);
            _onAchievementNotchGranted?.Subscribe(() => IncreaseNotches(1)).AddTo(_subs);
        }

        private void OnDisable()
        {
            ServiceLocator.Unregister<IEquipmentService>(this);
            ServiceLocator.GetOrDefault<ISaveableRegistry>()?.Unregister(this);
            _subs.Clear();
        }

        private void Awake()
        {
            _ctx = new EquipmentContext
            {
                Stats     = GetComponent<PlayerStats>(),
                Feedback  = GetComponent<PlayerFeedback>(),
                Events    = ServiceLocator.GetOrDefault<IEventChannelRegistry>(),
                SkillMods = GetComponent<SkillModifierRegistry>(),
                WeaponMgr = GetComponent<WeaponManager>(),
            };
            Debug.Assert(_config      != null, "[EquipmentManager] _config 未赋值，请在 Inspector 中指定 EquipmentConfigSO。",  this);
            Debug.Assert(_charmCatalog != null, "[EquipmentManager] _charmCatalog 未赋值，请在 Inspector 中指定 CharmCatalogSO。", this);
            _currentNotchCapacity = _config.initialNotchCount;

            Debug.Assert(_ctx.Stats     != null, "[EquipmentManager] 缺少 PlayerStats，护符效果无法修改属性。",    this);
            Debug.Assert(_ctx.Feedback  != null, "[EquipmentManager] 缺少 PlayerFeedback，护符效果无法触发反馈。", this);
            Debug.Assert(_ctx.SkillMods != null, "[EquipmentManager] 缺少 SkillModifierRegistry。",             this);
        }

        // ── 查询属性 ─────────────────────────────────────────────────────────
        public int UsedNotches  => _usedNotches;  // 缓存值，避免每次调用 LINQ Sum
        public int TotalNotches => _currentNotchCapacity;
        public IReadOnlyList<CharmSO> Equipped  => _equipped;
        public IReadOnlyList<CharmSO> Collected => _collected;

        // ── 装备操作 ─────────────────────────────────────────────────────────
        /// <summary>
        /// 装备护符。返回 null 表示成功；返回错误字符串表示失败原因。
        /// </summary>
        public string TryEquipCharm(CharmSO charm)
        {
            if (charm == null)                    return "护符不存在";
            if (_equipped.Contains(charm))        return "已经装备";
            if (!_collected.Contains(charm))      return "尚未收集此护符";
            int remaining = _currentNotchCapacity - UsedNotches;
            if (charm.notchCost > remaining)
                return $"笔记不足（需要 {charm.notchCost}，剩余 {remaining}）";

            _equipped.Add(charm);
            _usedNotches += charm.notchCost;
            foreach (var fx in charm.effects) fx?.OnEquip(_ctx);
            _onCharmEquipped?.Raise(charm);
            _onEquipmentChanged?.Raise();
            return null;
        }

        public void UnequipCharm(CharmSO charm)
        {
            if (charm == null || !_equipped.Remove(charm)) return;
            _usedNotches -= charm.notchCost;
            foreach (var fx in charm.effects) fx?.OnUnequip(_ctx);
            _onCharmUnequipped?.Raise(charm);
            _onEquipmentChanged?.Raise();
        }

        /// <summary>将护符加入收藏（拾取时调用）。</summary>
        public void AddToCollection(string charmId)
        {
            var charm = _charmCatalog.Find(charmId);
            if (charm == null) { Debug.LogWarning($"[EquipmentManager] 找不到护符: {charmId}"); return; }
            if (!_collected.Contains(charm))
                _collected.Add(charm);
        }

        public void IncreaseNotches(int amount)
        {
            _currentNotchCapacity += amount;
            _onEquipmentChanged?.Raise();
        }

        // ── ISaveable ────────────────────────────────────────────────────────
        public void OnSave(SaveData data)
        {
            data.Equipment.EquippedCharmIds.Clear();
            data.Equipment.EquippedCharmIds.AddRange(_equipped.Select(c => c.charmId));
            data.Equipment.OwnedCharmIds.Clear();
            data.Equipment.OwnedCharmIds.AddRange(_collected.Select(c => c.charmId));
            data.Equipment.MaxNotches = _currentNotchCapacity;
        }

        public void OnLoad(SaveData data)
        {
            // 卸下所有当前护符（不触发事件，逆序遍历避免 ToList() GC 分配）
            for (int i = _equipped.Count - 1; i >= 0; i--)
                foreach (var fx in _equipped[i].effects) fx?.OnUnequip(_ctx);
            _equipped.Clear();
            _usedNotches = 0;

            // 恢复 Notch 上限（若存档值为 0 则使用初始默认值）
            _currentNotchCapacity = data.Equipment.MaxNotches > 0
                ? data.Equipment.MaxNotches
                : _config.initialNotchCount;

            // 从 CharmCatalog 按 ID 恢复收藏并重新装备
            _collected.Clear();
            foreach (var id in data.Equipment.OwnedCharmIds)
            {
                var charm = _charmCatalog.Find(id);
                if (charm != null && !_collected.Contains(charm))
                    _collected.Add(charm);
            }

            foreach (var id in data.Equipment.EquippedCharmIds)
            {
                var charm = _charmCatalog.Find(id);
                if (charm != null) TryEquipCharm(charm);
            }

            _onEquipmentChanged?.Raise();
        }
    }
}