using FluidExplorer.Services.FileSystem;
using FluidExplorer.Services.Icons;
using FluidExplorer.Services.Operations;
using FluidExplorer.Services.Search;
using FluidExplorer.ViewModels;
using Microsoft.UI.Dispatching;

namespace FluidExplorer.Services;

/// <summary>组合根：所有服务在这里创建、装配，并交给视图模型。</summary>
public sealed class AppServices
{
    public AppServices(DispatcherQueue ui)
    {
        Ui = ui;
        Settings = AppSettings.Load();
        FileSystem = new FastFileSystemService();
        Search = new SearchService(FileSystem);
        Icons = CreateIconService(ui);
        Operations = CreateOperationService();
        Main = new MainViewModel(FileSystem, Search, Operations, Icons, Settings, ui);
    }

    public DispatcherQueue Ui { get; }
    public AppSettings Settings { get; }
    public IFileSystemService FileSystem { get; }
    public SearchService Search { get; }
    public IIconService Icons { get; }
    public IFileOperationService Operations { get; }
    public MainViewModel Main { get; }

    /// <summary>接入 Windows 外壳原版图标（imageres.dll / IShellItemImageFactory）。</summary>
    private static IIconService CreateIconService(DispatcherQueue ui)
    {
        try
        {
            return new ShellIconService(ui);
        }
        catch
        {
            return new PlaceholderIconService();
        }
    }

    /// <summary>接入文件操作队列引擎。</summary>
    private static IFileOperationService CreateOperationService()
    {
        try
        {
            return new FileOperationService();
        }
        catch
        {
            return new PlaceholderOperationService();
        }
    }

    /// <summary>接入 NTFS USN/MFT 索引（Everything 式极速搜索）。</summary>
    public void WireSearchIndex()
    {
        Search.IndexFactory = volumeRoot =>
        {
            try
            {
                return new FluidExplorer.Services.Search.Usn.UsnVolumeIndex(volumeRoot);
            }
            catch
            {
                // 非 NTFS 卷等异常情况：该卷不建索引，搜索自动退化为实时扫描
                return null;
            }
        };
    }
}