using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Threading.Tasks;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using Sln.Wcs.Repository.service.@base;
using Sln.Wcs.UI.Views.Base;

namespace Sln.Wcs.UI.ViewModels.Base;

public interface ICrudPageViewModel
{
    void Load();
    Avalonia.Controls.Control CreateView();
    string PageTitle { get; }
}

public abstract partial class CrudPageViewModel<T> : ObservableObject, ICrudPageViewModel where T : class, new()
{
    protected readonly IBaseService<T> _service;

    [ObservableProperty]
    private ObservableCollection<T> _items = new();

    [ObservableProperty]
    private T? _selectedItem;

    [ObservableProperty]
    private string _searchText = string.Empty;

    [ObservableProperty]
    private string _pageTitle = string.Empty;

    [ObservableProperty]
    private string _statusText = string.Empty;

    public abstract List<FieldConfig> FieldConfigs { get; }
    public abstract Avalonia.Controls.Control CreateView();

    /// <summary>
    /// Expression to search by name/code field. Override to customize.
    /// Returns null to skip filtering (load all).
    /// </summary>
    protected abstract Expression<Func<T, bool>>? BuildSearchExpression(string search);

    protected CrudPageViewModel(IBaseService<T> service)
    {
        _service = service;
        AddCommand = new AsyncRelayCommand(Add);
        EditCommand = new AsyncRelayCommand(Edit);
    }

    [RelayCommand]
    public void Load()
    {
        try
        {
            List<T> list;
            if (string.IsNullOrWhiteSpace(SearchText))
            {
                list = _service.Query();
            }
            else
            {
                var exp = BuildSearchExpression(SearchText);
                list = exp != null ? _service.Query(exp) : _service.Query();
            }
            Items = new ObservableCollection<T>(list);
            StatusText = $"共 {list.Count} 条记录";
        }
        catch (Exception ex)
        {
            StatusText = $"加载失败: {ex.Message}";
        }
    }

    public AsyncRelayCommand AddCommand { get; }
    public AsyncRelayCommand EditCommand { get; }

    private async System.Threading.Tasks.Task Add()
    {
        var entity = new T();
        var editor = new EntityEditWindow();
        var result = await editor.ShowDialog(entity, FieldConfigs, false, GetMainWindow());
        if (result)
        {
            _service.Insert(entity);
            Load();
            StatusText = "新增成功";
        }
    }

    private async System.Threading.Tasks.Task Edit()
    {
        if (SelectedItem is null) return;
        var editor = new EntityEditWindow();
        var result = await editor.ShowDialog(SelectedItem, FieldConfigs, true, GetMainWindow());
        if (result)
        {
            _service.Update(SelectedItem);
            Load();
            StatusText = "编辑成功";
        }
    }

    [RelayCommand]
    private void Delete()
    {
        if (SelectedItem is null) return;
        var prop = typeof(T).GetProperty("objId") ?? typeof(T).GetProperty("ObjId");
        if (prop is null) return;
        var id = prop.GetValue(SelectedItem);
        _service.DeleteById(id!);
        Load();
        StatusText = "删除成功";
    }

    [RelayCommand]
    private void Search()
    {
        Load();
    }

    private Avalonia.Controls.Window GetMainWindow()
    {
        return (Avalonia.Controls.Window)Avalonia.Application.Current!
            .ApplicationLifetime!.GetType()
            .GetProperty("MainWindow")!
            .GetValue(Avalonia.Application.Current.ApplicationLifetime)!;
    }
}