using AuroraDesk.Core.Interfaces;
using AuroraDesk.Core.Entities;
using Microsoft.Extensions.Logging;
using System.Collections.ObjectModel;
using System.Collections.Generic;
using ReactiveUI;

namespace AuroraDesk.Infrastructure.Services;

/// <summary>
/// 导航状态管理服务实现
/// 使用字典缓存优化查找性能，减少循环遍历
/// </summary>
public class NavigationStateService : INavigationStateService
{
    private readonly ILogger<NavigationStateService>? _logger;
    
    // 使用字典缓存加速 ViewModel -> NavigationItem 的查找（O(1) 时间复杂度）
    private readonly Dictionary<IRoutableViewModel, NavigationItem> _viewModelToItemMap = new();
    
    // 使用字典缓存加速子项 -> 父项的查找（O(1) 时间复杂度）
    private readonly Dictionary<NavigationItem, NavigationItem> _childToParentMap = new();
    
    // 所有导航项的扁平化列表（用于状态重置）
    private readonly List<NavigationItem> _allItems = new();
    
    // 当前导航项集合的引用
    private ObservableCollection<NavigationItem>? _navigationItems;

    public NavigationStateService(ILogger<NavigationStateService>? logger = null)
    {
        _logger = logger;
    }

    public void InitializeStateMap(ObservableCollection<NavigationItem> navigationItems)
    {
        _navigationItems = navigationItems;
        _viewModelToItemMap.Clear();
        _childToParentMap.Clear();
        _allItems.Clear();
        
        BuildStateMap(navigationItems, null);
        
        _logger?.LogInformation("导航状态映射已初始化，共 {Count} 个导航项", _allItems.Count);
    }

    private void BuildStateMap(ObservableCollection<NavigationItem> items, NavigationItem? parent)
    {
        foreach (var item in items)
        {
            _allItems.Add(item);
            
            // 建立 ViewModel 到 NavigationItem 的映射
            if (item.ViewModel != null)
            {
                _viewModelToItemMap[item.ViewModel] = item;
            }
            
            // 建立子项到父项的映射
            if (parent != null)
            {
                _childToParentMap[item] = parent;
            }
            
            // 递归处理子项
            if (item.HasChildren)
            {
                BuildStateMap(item.Children, item);
            }
        }
    }

    public NavigationItem? FindNavigationItemByViewModel(IRoutableViewModel viewModel)
    {
        // 使用字典查找，时间复杂度 O(1)，而不是原来的 O(n*m)
        return _viewModelToItemMap.TryGetValue(viewModel, out var item) ? item : null;
    }

    public NavigationItem? FindParentItem(NavigationItem childItem)
    {
        // 使用字典查找，时间复杂度 O(1)
        return _childToParentMap.TryGetValue(childItem, out var parent) ? parent : null;
    }

    public void ResetAllStates()
    {
        // 只遍历需要重置的项，避免不必要的属性设置
        var itemsToReset = new List<NavigationItem>();
        
        foreach (var item in _allItems)
        {
            if (item.IsSelected || item.IsExpanded)
            {
                itemsToReset.Add(item);
            }
        }
        
        // 批量重置状态，减少 ReactiveObject 的触发次数
        foreach (var item in itemsToReset)
        {
            if (item.IsSelected)
            {
                item.IsSelected = false;
            }
            if (item.IsExpanded)
            {
                item.IsExpanded = false;
            }
        }
        
        _logger?.LogDebug("已重置 {Count} 个导航项的状态", itemsToReset.Count);
    }

    public void ResetSelectionOnly()
    {
        // 只重置选中状态，不重置展开状态
        var itemsToReset = new List<NavigationItem>();
        
        foreach (var item in _allItems)
        {
            if (item.IsSelected)
            {
                itemsToReset.Add(item);
            }
        }
        
        foreach (var item in itemsToReset)
        {
            item.IsSelected = false;
        }
        
        _logger?.LogDebug("已重置 {Count} 个导航项的选中状态", itemsToReset.Count);
    }

    public void ResetOtherStates(NavigationItem? exceptItem)
    {
        if (exceptItem == null)
        {
            ResetAllStates();
            return;
        }

        var itemsToReset = new List<NavigationItem>();
        
        foreach (var item in _allItems)
        {
            if (item == exceptItem) continue;
            
            if (item.IsSelected || item.IsExpanded)
            {
                itemsToReset.Add(item);
            }
        }
        
        foreach (var item in itemsToReset)
        {
            if (item.IsSelected)
            {
                item.IsSelected = false;
            }
            if (item.IsExpanded)
            {
                item.IsExpanded = false;
            }
        }
        
        _logger?.LogDebug("已重置除指定项外的 {Count} 个导航项状态", itemsToReset.Count);
    }

    public void SelectItem(NavigationItem item)
    {
        if (item == null) return;
        
        // 先重置其他项的选中状态
        ResetSelectionOnly();
        
        // 选中当前项
        item.IsSelected = true;
        
        _logger?.LogDebug("已选中导航项: {Title}", item.Title);
    }

    public void ToggleExpand(NavigationItem item)
    {
        if (item == null || !item.HasChildren) return;
        
        item.IsExpanded = !item.IsExpanded;
        
        _logger?.LogDebug("切换导航项展开状态: {Title}, IsExpanded: {IsExpanded}", 
            item.Title, item.IsExpanded);
    }
}