using System;
using System.Threading;
using System.Threading.Tasks;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using TMPro;
using BaseGames.Core;
using BaseGames.Core.Events;
using BaseGames.Core.Save;
using BaseGames.Localization;

namespace BaseGames.UI.Menus
{
    /// <summary>
    /// 驱动主菜单存档槽选择面板（新游戏 / 继续 / 删除）。
    /// </summary>
    public class SaveSlotController : MonoBehaviour
    {
        [SerializeField] private SaveSlotUI[]      _slotUIs;

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

        private CancellationTokenSource _cts;

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

        private void OnEnable()
        {
            _cts = new CancellationTokenSource();
            var ct = _cts.Token;
            var task = RefreshAsync(ct);
            task.ContinueWith(t =>
            {
                if (t.IsFaulted && !(t.Exception?.InnerException is OperationCanceledException))
                    Debug.LogException(t.Exception?.InnerException ?? t.Exception, this);
            }, TaskScheduler.FromCurrentSynchronizationContext());
        }

        private void OnDisable()
        {
            _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]);
            }
        }

        /// <summary>选中指定槽位（新局或继续）。由 SaveSlotUI 内部按钮调用。</summary>
        public void OnSlotSelected(int slotIndex)
        {
            if (slotIndex < 0 || slotIndex >= _slotUIs.Length) return;
            _ = SelectSlotAsync(slotIndex);
        }

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

            if (svc.HasSave(slotIndex))
                await svc.LoadAsync(slotIndex);
            else
                svc.CreateSlot(slotIndex);

            _onSlotConfirmed?.Raise(slotIndex);
        }

        /// <summary>删除指定槽位存档并刷新 UI。由 SaveSlotUI 内部按钮调用。</summary>
        public void OnSlotDeleteRequested(int slotIndex)
        {
            if (slotIndex < 0 || slotIndex >= _slotUIs.Length) return;
            _ = 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);
        }
    }

    /// <summary>
    /// 单个存档槽卡片组件，负责显示存档摘要或空槽提示。
    /// </summary>
    public class SaveSlotUI : MonoBehaviour
    {
        [SerializeField] private TMP_Text   _playtimeText;
        [SerializeField] private TMP_Text   _regionText;
        [SerializeField] private TMP_Text   _lastSavedText;
        [SerializeField] private Image      _formIcon;
        [SerializeField] private GameObject _emptyIndicator;  // 空槽时显示的"新游戏"提示
        [SerializeField] private GameObject _dataIndicator;   // 有数据时显示的内容根
        [SerializeField] private Button     _selectButton;
        [SerializeField] private Button     _deleteButton;

        [Header("删除确认（可选）")]
        [Tooltip("删除确认对话框根节点，为 null 时删除按钮直接执行。")]
        [SerializeField] private GameObject _deleteConfirmRoot;
        [Tooltip("确认删除按钮。")]
        [SerializeField] private Button     _btnConfirmDelete;
        [Tooltip("取消删除按钮。")]
        [SerializeField] private Button     _btnCancelDelete;

        private int                _slotIndex;
        private SaveSlotController _controller;

        /// <summary>由 SaveSlotController 在 Awake 或初始化时调用以完成按钮绑定。</summary>
        public void Init(int slotIndex, SaveSlotController controller)
        {
            _slotIndex  = slotIndex;
            _controller = controller;

            if (_selectButton != null)
            {
                _selectButton.onClick.RemoveAllListeners();
                _selectButton.onClick.AddListener(() => _controller.OnSlotSelected(_slotIndex));
            }

            if (_deleteButton != null)
            {
                _deleteButton.onClick.RemoveAllListeners();
                // 配置了确认对话框时先弹出确认，未配置时直接删除
                _deleteButton.onClick.AddListener(ShowDeleteConfirm);
            }

            if (_btnConfirmDelete != null)
            {
                _btnConfirmDelete.onClick.RemoveAllListeners();
                _btnConfirmDelete.onClick.AddListener(() =>
                {
                    HideDeleteConfirm();
                    _controller.OnSlotDeleteRequested(_slotIndex);
                });
            }

            if (_btnCancelDelete != null)
            {
                _btnCancelDelete.onClick.RemoveAllListeners();
                _btnCancelDelete.onClick.AddListener(HideDeleteConfirm);
            }

            HideDeleteConfirm();
        }

        /// <summary>用摘要数据刷新显示；summary 为 null 表示空槽。</summary>
        public void Refresh(SlotSummary summary)
        {
            bool hasData = summary != null;

            if (_emptyIndicator != null) _emptyIndicator.SetActive(!hasData);
            if (_dataIndicator  != null) _dataIndicator.SetActive(hasData);
            if (_deleteButton   != null) _deleteButton.gameObject.SetActive(hasData);

            // 刷新时重置确认对话框状态
            HideDeleteConfirm();

            if (!hasData) return;

            if (_playtimeText  != null) _playtimeText.text  = FormatPlaytime(summary.Playtime);

            if (_regionText != null)
            {
                string key = summary.SceneName ?? string.Empty;
                string loc = !string.IsNullOrEmpty(key)
                    ? LocalizationManager.Get(key, LocalizationTable.UI)
                    : null;
                _regionText.text = !string.IsNullOrEmpty(loc) && loc != key ? loc : key;
            }

            if (_lastSavedText != null) _lastSavedText.text = FormatDateTime(summary.LastSaved);
        }

        // ── 删除确认 ──────────────────────────────────────────────────────────

        /// <summary>
        /// 显示删除确认对话框。
        /// 未配置 _deleteConfirmRoot 时直接执行删除（向下兼容旧 Prefab）。
        /// </summary>
        private void ShowDeleteConfirm()
        {
            if (_deleteConfirmRoot == null)
            {
                // 旧 Prefab 未添加确认根节点，直接删除
                _controller.OnSlotDeleteRequested(_slotIndex);
                return;
            }
            _deleteConfirmRoot.SetActive(true);
            // 手柄导航：将焦点移至"确认"按钮，防止误触选择按钮
            EventSystem.current?.SetSelectedGameObject(_btnConfirmDelete?.gameObject);
        }

        private void HideDeleteConfirm()
        {
            if (_deleteConfirmRoot != null) _deleteConfirmRoot.SetActive(false);
        }

        // ── 格式化工具 ────────────────────────────────────────────────────────

        private static string FormatPlaytime(float seconds)
        {
            int h = (int)(seconds / 3600);
            int m = (int)((seconds % 3600) / 60);
            int s = (int)(seconds % 60);
            return $"{h:D2}:{m:D2}:{s:D2}";
        }

        private static string FormatDateTime(string iso8601)
        {
            if (string.IsNullOrEmpty(iso8601)) return string.Empty;
            if (DateTime.TryParse(iso8601,
                    System.Globalization.CultureInfo.InvariantCulture,
                    System.Globalization.DateTimeStyles.RoundtripKind,
                    out DateTime dt))
            {
                return dt.ToLocalTime().ToString("yyyy-MM-dd HH:mm");
            }
            return iso8601;
        }
    }
}