using System;
using System.Threading;
using System.Threading.Tasks;
using UnityEngine;
using UnityEngine.UI;
using BaseGames.Core;
using BaseGames.Core.Events;
using BaseGames.Core.Save;
using BaseGames.UI;
using BaseGames.UI.MainMenu;

namespace BaseGames.UI.Menus
{
    /// <summary>主菜单存档槽面板的打开语境。</summary>
    public enum SaveSlotPanelMode
    {
        /// <summary>继续游戏：仅有档槽可选，点击即读档进入。</summary>
        Continue,
        /// <summary>新游戏：空槽 → 模式选择 → 建档；有档槽 → 覆盖确认 → 模式选择 → 建档。</summary>
        NewGame,
    }

    /// <summary>
    /// 驱动主菜单存档槽选择面板（新游戏 / 继续 / 删除）。
    ///
    /// <para>本面板经 <see cref="IUINavigator"/> 压栈（由主菜单控制器 Push）。覆盖确认 / 模式选择
    /// 这两个子对话框走导航器结果面板（<see cref="ConfirmDialogController.ShowAsync"/> /
    /// <see cref="NewGameModeController.ShowAsync"/>）——线性 <c>await</c>，无回调嵌套，ESC 逐层回退。</para>
    ///
    /// 前端选档流程：
    ///   · 新游戏开档前先选模式（普通 / 钢铁之魂），占用槽位需覆盖确认。
    ///   · 删除强制走通用确认对话框（无静默删除旁路）。
    ///   · 卡片展示游玩时长 / 区域 / 货币 / 生命 / 钢魂徽章。
    /// 模式由主菜单控制器在压栈前经 <see cref="SetMode"/> 指定。
    /// </summary>
    public class SaveSlotController : UIPanelBase
    {
        [SerializeField] private SaveSlotUI[] _slotUIs;

        [Header("子对话框（Inspector 注入，同处 MainMenu 场景，走导航器结果面板）")]
        [Tooltip("通用确认对话框，用于覆盖 / 删除确认。为空时：覆盖退化为直接建档，删除被忽略（绝不静默删除）。")]
        [SerializeField] private ConfirmDialogController _confirmDialog;
        [Tooltip("新游戏模式选择面板。为空时新游戏退化为普通模式。")]
        [SerializeField] private NewGameModeController   _modeSelect;

        [Header("Event Channels")]
        [SerializeField] private IntEventChannelSO _onSlotConfirmed;

        [Header("焦点")]
        [Tooltip("面板默认聚焦的按钮，通常为第一个存档槽的选择按钮。")]
        [SerializeField] private Button _defaultFocusButton;

        private SaveSlotPanelMode       _mode = SaveSlotPanelMode.NewGame;
        private CancellationTokenSource _cts;

        private void Awake()
        {
            for (int i = 0; i < _slotUIs.Length; i++)
                if (_slotUIs[i] != null) _slotUIs[i].Init(i, this);
        }

        /// <summary>由主菜单控制器在压栈前调用，决定本次打开语境。</summary>
        public void SetMode(SaveSlotPanelMode mode) => _mode = mode;

        /// <summary>默认 / 恢复焦点回到首个存档槽按钮。</summary>
        protected override GameObject ResolveFirstSelected()
            => _defaultFocusButton != null ? _defaultFocusButton.gameObject : null;

        // ── 生命周期（UIPanelBase 驱动）──────────────────────────────────────
        protected override void OnPanelOpen()
        {
            _cts = new CancellationTokenSource();
            RunGuarded(RefreshAsync(_cts.Token));
        }

        protected override void OnPanelClose()
        {
            // 注意：不再级联 Close 子对话框（旧实现于此强关 confirm/mode，是"ESC 一次关多层"的根因）。
            // 子对话框生命周期完全交给导航器；若本面板随场景卸载，其 await 由结果面板兜底收口。
            _cts?.Cancel();
            _cts?.Dispose();
            _cts = null;
        }

        private async Task RefreshAsync(CancellationToken ct = default)
        {
            var svc = ServiceLocator.GetOrDefault<ISaveService>();
            if (svc == null) return;

            var tasks = new Task<SlotSummary>[_slotUIs.Length];
            for (int i = 0; i < _slotUIs.Length; i++)
                tasks[i] = svc.GetSlotSummaryAsync(i);

            var summaries = await Task.WhenAll(tasks);
            ct.ThrowIfCancellationRequested();   // 组件已失活时不写 UI

            for (int i = 0; i < _slotUIs.Length; i++)
            {
                if (_slotUIs[i] == null) continue;
                _slotUIs[i].Refresh(summaries[i], _mode);
            }
        }

        // ── 选槽 ────────────────────────────────────────────────────────────────
        /// <summary>选中指定槽位。行为取决于当前模式与槽位是否有档。由 SaveSlotUI 内部按钮调用。</summary>
        public void OnSlotSelected(int slotIndex)
        {
            if (slotIndex < 0 || slotIndex >= _slotUIs.Length) return;
            RunGuarded(HandleSlotSelectedAsync(slotIndex));
        }

        private async Task HandleSlotSelectedAsync(int slotIndex)
        {
            var svc = ServiceLocator.GetOrDefault<ISaveService>();
            if (svc == null) return;
            var ct = _cts?.Token ?? CancellationToken.None;

            if (_mode == SaveSlotPanelMode.Continue)
            {
                if (!svc.HasSave(slotIndex)) return;   // 继续模式：空槽不可选
                await ContinueSlotAsync(slotIndex);
                return;
            }

            // ── 新游戏模式 ──
            if (svc.HasSave(slotIndex) && _confirmDialog != null)
            {
                bool ok = await _confirmDialog.ShowAsync("CONFIRM_OVERWRITE_TITLE", "CONFIRM_OVERWRITE_BODY", ct);
                if (!ok) return;                       // 取消覆盖
            }

            DifficultyLevel level = DifficultyLevel.Normal;
            if (_modeSelect != null)
            {
                DifficultyLevel? chosen = await _modeSelect.ShowAsync(ct);
                if (chosen == null) return;            // 取消模式选择
                level = chosen.Value;
            }

            await StartNewGameAsync(slotIndex, level);
        }

        private async Task StartNewGameAsync(int slotIndex, DifficultyLevel level)
        {
            var svc = ServiceLocator.GetOrDefault<ISaveService>();
            if (svc == null) return;

            // 覆盖既有档：先删盘，确保旧数据不残留（建档仅初始化内存，写盘发生在首次存档）
            if (svc.HasSave(slotIndex))
                await svc.DeleteSlotAsync(slotIndex);

            bool steel = level == DifficultyLevel.SteelSoul;
            svc.CreateSlot(slotIndex, steel);
            ServiceLocator.GetOrDefault<IDifficultyService>()?.BeginNewGame(level);

            _onSlotConfirmed?.Raise(slotIndex);
        }

        private async Task ContinueSlotAsync(int slotIndex)
        {
            var svc = ServiceLocator.GetOrDefault<ISaveService>();
            if (svc == null) return;

            bool ok = await svc.LoadAsync(slotIndex);
            if (!ok) return;   // 损坏 / 不存在：不前进（后续可接错误提示）

            _onSlotConfirmed?.Raise(slotIndex);
        }

        // ── 删除（强制确认）────────────────────────────────────────────────────
        /// <summary>请求删除指定槽位。强制经通用确认对话框；无对话框时忽略，绝不静默删除。</summary>
        public void OnSlotDeleteRequested(int slotIndex)
        {
            if (slotIndex < 0 || slotIndex >= _slotUIs.Length) return;

            if (_confirmDialog == null)
            {
                Debug.LogWarning("[SaveSlotController] 未配置 ConfirmDialog，删除请求被忽略（防止静默删除）。");
                return;
            }
            RunGuarded(DeleteFlowAsync(slotIndex));
        }

        private async Task DeleteFlowAsync(int slotIndex)
        {
            var ct = _cts?.Token ?? CancellationToken.None;
            bool ok = await _confirmDialog.ShowAsync("CONFIRM_DELETE_TITLE", "CONFIRM_DELETE_BODY", ct);
            if (!ok) return;
            await DeleteAndRefreshAsync(slotIndex);
        }

        private async Task DeleteAndRefreshAsync(int slotIndex)
        {
            var svc = ServiceLocator.GetOrDefault<ISaveService>();
            if (svc == null) return;
            await svc.DeleteSlotAsync(slotIndex);
            await RefreshAsync(_cts?.Token ?? CancellationToken.None);
        }

        // ── 工具 ──────────────────────────────────────────────────────────────
        /// <summary>fire-and-forget Task 的统一异常护栏（吞掉取消，记录其余）。</summary>
        private void RunGuarded(Task task)
        {
            task.ContinueWith(t =>
            {
                if (t.IsFaulted && !(t.Exception?.InnerException is OperationCanceledException))
                    Debug.LogException(t.Exception?.InnerException ?? t.Exception, this);
            }, TaskScheduler.FromCurrentSynchronizationContext());
        }
    }
}