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

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;        // 存档槽 UI（数量由 Inspector 决定）

        [Header("Event Channels")]
        [SerializeField] private IntEventChannelSO _onSlotConfirmed; // 携带槽索引，供 GameManager 监听

        private void OnEnable()
        {
            var task = RefreshAsync();
            task.ContinueWith(t =>
            {
                if (t.IsFaulted)
                    Debug.LogException(t.Exception?.InnerException ?? t.Exception, this);
            }, TaskScheduler.FromCurrentSynchronizationContext());
        }

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

            // 并行加载所有槽位摘要，减少主菜单等待时间
            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);

            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();
        }
    }

    /// <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;

        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();
                _deleteButton.onClick.AddListener(() => _controller.OnSlotDeleteRequested(_slotIndex));
            }
        }

        /// <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);

            if (!hasData) return;

            if (_playtimeText  != null) _playtimeText.text  = FormatPlaytime(summary.Playtime);
            if (_regionText    != null) _regionText.text    = summary.SceneName ?? string.Empty;
            if (_lastSavedText != null) _lastSavedText.text = FormatDateTime(summary.LastSaved);
        }

        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;
        }
    }
}