using Microsoft.Win32;
using System.Runtime.InteropServices;
// ReSharper disable UnusedMember.Local

namespace Melskin.Controls;

/// <summary>
/// Vista风格的文件夹选择对话框，支持多选、初始文件夹设置等功能。
/// </summary>
public sealed class VistaFolderBrowserDialog
{
    /// <summary>
    /// 创建原生的IFileOpenDialog实例。
    /// </summary>
    /// <returns>IFileOpenDialog实例。</returns>
    private static IFileOpenDialog CreateNativeDialog() { return (IFileOpenDialog)new FileOpenDialog(); }

    /// <summary>
    /// 获取对话框的选项配置（Fos枚举）。
    /// </summary>
    /// <returns>Fos选项集合。</returns>
    private Fos GetDialogOptions()
    {
        var options = Fos.Pickfolders;
        if (Multiselect)
        {
            options |= Fos.Allowmultiselect;
        }

        if (!AllowNonStoragePlaces)
        {
            options |= Fos.Forcefilesystem;
        }

        return options;
    }

    /// <summary>
    /// 获取指定Shell项的路径和元素名称。
    /// </summary>
    /// <param name="item">Shell项。</param>
    /// <param name="path">输出：文件系统路径。</param>
    /// <param name="elementName">输出：元素名称。</param>
    private static void GetPathAndElementName(IShellItem item, out string? path, out string elementName)
    {
        item.GetDisplayName(Sigdn.Parentrelativeforaddressbar, out elementName);
        try
        {
            item.GetDisplayName(Sigdn.Filesyspath, out path);
        }
        catch (ArgumentException ex) when (ex.HResult == -2147024809)
        {
            path = null;
        }
    }

    /// <summary>
    /// 设置对话框选择结果到属性（支持单选和多选）。
    /// </summary>
    /// <param name="dialog">IFileOpenDialog实例。</param>
    private void SetDialogResults(IFileOpenDialog dialog)
    {
        IShellItem item;
        if (!Multiselect)
        {
            dialog.GetResult(out item);
            GetPathAndElementName(item, out var path, out var value);
            SelectedPath = path;
            SelectedPaths = [path];
            SelectedElementName = value;
            SelectedElementNames = [value];
        }
        else
        {
            dialog.GetResults(out var items);

            items.GetCount(out var count);

            SelectedPaths = new string[count];
            SelectedElementNames = new string[count];

            for (uint i = 0; i < count; ++i)
            {
                items.GetItemAt(i, out item);
                GetPathAndElementName(item, out var path, out var value);
                SelectedPaths[i] = path;
                SelectedElementNames[i] = value;
            }

            SelectedPath = null;
            SelectedElementName = null;
        }
    }

    /// <summary>
    /// 设置对话框的初始文件夹。
    /// </summary>
    /// <param name="dialog">IFileOpenDialog实例。</param>
    private void SetInitialFolder(IFileOpenDialog dialog)
    {
        if (!string.IsNullOrEmpty(SelectedPath))
        {
            uint atts = 0;
            if (NativeMethods.SHILCreateFromPath(SelectedPath, out var idl, ref atts) == 0 &&
                NativeMethods.SHCreateShellItem(IntPtr.Zero, IntPtr.Zero, idl, out var item) == 0)
            {
                dialog.SetFolder(item);
            }
        }
    }

    /// <summary>
    /// 设置对话框的选项。
    /// </summary>
    /// <param name="dialog">IFileOpenDialog实例。</param>
    private void SetOptions(IFileOpenDialog dialog)
    {
        var options = GetDialogOptions();
        if (!ShowNewFolderButton)
        {
            options |= Fos.Notestfilecreate;
        }
        dialog.SetOptions(options);
    }

    /// <summary>
    /// 显示对话框，无所有者窗口。
    /// </summary>
    /// <returns>用户是否选择了文件夹。</returns>
    public bool ShowDialog() { return ShowDialog(IntPtr.Zero); }

    /// <summary>
    /// 显示对话框，指定WPF窗口作为所有者。
    /// </summary>
    /// <param name="owner">WPF窗口。</param>
    /// <returns>用户是否选择了文件夹。</returns>
    public bool ShowDialog(Window? owner)
    { return ShowDialog(owner == null ? IntPtr.Zero : new WindowInteropHelper(owner).Handle); }

    /// <summary>
    /// 显示对话框，指定Win32窗口作为所有者。
    /// </summary>
    /// <param name="owner">Win32窗口。</param>
    /// <returns>用户是否选择了文件夹。</returns>
    public bool ShowDialog(IWin32Window? owner) { return ShowDialog(owner?.Handle ?? IntPtr.Zero); }

    /// <summary>
    /// 显示对话框，指定窗口句柄作为所有者。
    /// </summary>
    /// <param name="owner">窗口句柄。</param>
    /// <returns>用户是否选择了文件夹。</returns>
    public bool ShowDialog(IntPtr owner)
    {
        if (Environment.OSVersion.Version.Major < 6)
        {
            throw new InvalidOperationException("对话框需要至少在Visia系统以上才能使用");
        }

        var dialog = CreateNativeDialog();
        try
        {
            SetInitialFolder(dialog);
            SetOptions(dialog);

            if (!string.IsNullOrEmpty(Title))
            {
                dialog.SetTitle(Title);
            }

            if (dialog.Show(owner) != 0)
            {
                return false;
            }

            SetDialogResults(dialog);

            return true;
        }
        finally
        {
            Marshal.ReleaseComObject(dialog);
        }
    }

    /// <summary>
    /// 是否允许选择非存储位置（如库、虚拟文件夹）。
    /// </summary>
    public bool AllowNonStoragePlaces { get; set; }

    /// <summary>
    /// 是否允许多选文件夹。
    /// </summary>
    public bool Multiselect { get; set; }

    /// <summary>
    /// 选中的元素名称（单选时）。
    /// </summary>
    public string? SelectedElementName { get; private set; }

    /// <summary>
    /// 选中的所有元素名称（多选时）。
    /// </summary>
    public string[]? SelectedElementNames { get; private set; }

    /// <summary>
    /// 选中的文件夹路径（单选时）。
    /// </summary>
    public string? SelectedPath { get; set; }

    /// <summary>
    /// 选中的所有文件夹路径（多选时）。
    /// </summary>
    public string?[]? SelectedPaths { get; private set; }

    // 属性声明
    /// <summary>
    /// 获取或设置对话框的标题。
    /// </summary>
    public string? Title { get; set; }

    /// <summary>
    /// 是否显示新建文件夹按钮。
    /// </summary>
    public bool ShowNewFolderButton { get; set; } = true;

    // 以下为内部COM接口和枚举定义，通常无需注释
    [ComImport]
    [Guid("DC1C5A9C-E88A-4dde-A5A1-60F82A20AEF7")]
    private class FileOpenDialog
    {
    }

    /// <summary>
    /// 提供了与Windows Shell交互所需的一些本地方法。这些方法主要用于实现文件夹浏览器对话框的功能，如获取当前活动窗口句柄、从给定路径创建项目标识符列表以及根据PIDL创建IShellItem接口实例。
    /// </summary>
    private class NativeMethods
    {
        /// <summary>
        /// 获取当前活动窗口的句柄。
        /// </summary>
        /// <returns>当前活动窗口的句柄。</returns>
        [DllImport("user32.dll")]
        public static extern IntPtr GetActiveWindow();

        /// <summary>
        /// 从给定的PIDL创建一个IShellItem接口实例。
        /// </summary>
        /// <param name="pidlParent">父项的PIDL。如果为IntPtr.Zero，则表示桌面。</param>
        /// <param name="psfParent">父项的IShellFolder接口指针。如果为IntPtr.Zero，则使用默认的桌面文件夹。</param>
        /// <param name="pidl">要创建IShellItem接口实例的PIDL。</param>
        /// <param name="ppsi">输出参数，返回创建的IShellItem接口实例。</param>
        /// <returns>如果函数成功，则返回0；否则返回错误代码。</returns>
        [DllImport("shell32.dll")]
        public static extern int SHCreateShellItem(
            IntPtr pidlParent,
            IntPtr psfParent,
            IntPtr pidl,
            out IShellItem ppsi);

        /// <summary>
        /// 从给定的路径创建一个项目标识符列表。
        /// </summary>
        /// <param name="pszPath">要转换为项目标识符列表的路径字符串。</param>
        /// <param name="ppIdl">输出参数，用于接收指向项目标识符列表的指针。</param>
        /// <param name="rgflnOut">输出参数，返回关于解析路径的信息。</param>
        /// <returns>如果函数成功，则返回0；否则返回错误代码。</returns>
        [DllImport("shell32.dll")]
        public static extern int SHILCreateFromPath(
            [MarshalAs(UnmanagedType.LPWStr)] string? pszPath,
            out IntPtr ppIdl,
            ref uint rgflnOut);
    }

    [Flags]
    private enum Fos
    {
        Allnonstorageitems = 0x80,

        Allowmultiselect = 0x200,

        Createprompt = 0x2000,

        Defaultnominimode = 0x20000000,

        Dontaddtorecent = 0x2000000,

        Filemustexist = 0x1000,

        Forcefilesystem = 0x40,     

        Forceshowhidden = 0x10000000,

        Hidemruplaces = 0x20000,

        Hidepinnedplaces = 0x40000,

        Nochangedir = 8,

        Nodereferencelinks = 0x100000,

        Noreadonlyreturn = 0x8000,

        Notestfilecreate = 0x10000,

        Novalidate = 0x100,

        Overwriteprompt = 2,

        Pathmustexist = 0x800,

        Pickfolders = 0x20,

        Shareaware = 0x4000,

        Strictfiletypes = 4
    }

    [ComImport]
    [Guid("d57c7288-d4ad-4768-be02-9d969532d960")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [CoClass(typeof(FileOpenDialog))]
    private interface IFileOpenDialog
    {
        [PreserveSig]
        int Show([In] IntPtr parent);

        void SetFileTypes([In] uint cFileTypes, [In][MarshalAs(UnmanagedType.Struct)] ref IntPtr rgFilterSpec);

        void SetFileTypeIndex([In] uint iFileType);

        void GetFileTypeIndex(out uint piFileType);

        void Advise([In][MarshalAs(UnmanagedType.Interface)] IntPtr pfde, out uint pdwCookie);

        void Unadvise([In] uint dwCookie);

        void SetOptions([In] Fos fos);

        void GetOptions(out Fos pfos);

        void SetDefaultFolder([In][MarshalAs(UnmanagedType.Interface)] IShellItem psi);

        void SetFolder([In][MarshalAs(UnmanagedType.Interface)] IShellItem psi);

        void GetFolder([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);

        void GetCurrentSelection([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);

        void SetFileName([In][MarshalAs(UnmanagedType.LPWStr)] string pszName);

        void GetFileName([MarshalAs(UnmanagedType.LPWStr)] out string pszName);

        void SetTitle([In][MarshalAs(UnmanagedType.LPWStr)] string? pszTitle);

        void SetOkButtonLabel([In][MarshalAs(UnmanagedType.LPWStr)] string pszText);

        void SetFileNameLabel([In][MarshalAs(UnmanagedType.LPWStr)] string pszLabel);

        void GetResult([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);

        void AddPlace([In][MarshalAs(UnmanagedType.Interface)] IShellItem psi, FileDialogCustomPlace fdcp);

        void SetDefaultExtension([In][MarshalAs(UnmanagedType.LPWStr)] string pszDefaultExtension);

        void Close([MarshalAs(UnmanagedType.Error)] int hr);

        void SetClientGuid([In] ref Guid guid);

        void ClearClientData();

        void SetFilter([MarshalAs(UnmanagedType.Interface)] IntPtr pFilter);

        void GetResults([MarshalAs(UnmanagedType.Interface)] out IShellItemArray ppenum);

        void GetSelectedItems([MarshalAs(UnmanagedType.Interface)] out IShellItemArray ppsai);
    }

    /// <summary>
    /// 代表一个Shell项，提供了获取项的名称、属性、父项以及与其他项比较等功能。
    /// </summary>
    [ComImport]
    [Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IShellItem
    {
        void BindToHandler(
            [In][MarshalAs(UnmanagedType.Interface)] IntPtr pbc,
            [In] ref Guid bhid,
            [In] ref Guid riid,
            out IntPtr ppv);

        void GetParent([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);

        void GetDisplayName([In] Sigdn sigdnName, [MarshalAs(UnmanagedType.LPWStr)] out string ppszName);

        void GetAttributes([In] uint sfgaoMask, out uint psfgaoAttribs);

        void Compare([In][MarshalAs(UnmanagedType.Interface)] IShellItem psi, [In] uint hint, out int piOrder);
    }

    [ComImport]
    [Guid("B63EA76D-1F85-456F-A19C-48159EFA858B")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IShellItemArray
    {
        void BindToHandler(
            [In][MarshalAs(UnmanagedType.Interface)] IntPtr pbc,
            [In] ref Guid rbhid,
            [In] ref Guid riid,
            out IntPtr ppvOut);

        void GetPropertyStore([In] int flags, [In] ref Guid riid, out IntPtr ppv);

        void GetPropertyDescriptionList(
            [In][MarshalAs(UnmanagedType.Struct)] ref IntPtr keyType,
            [In] ref Guid riid,
            out IntPtr ppv);

        void GetAttributes(
            [In][MarshalAs(UnmanagedType.I4)] IntPtr dwAttribFlags,
            [In] uint sfgaoMask,
            out uint psfgaoAttribs);

        void GetCount(out uint pdwNumItems);

        void GetItemAt([In] uint dwIndex, [MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);

        void EnumItems([MarshalAs(UnmanagedType.Interface)] out IntPtr ppenumShellItems);
    }

    private enum Sigdn : uint
    {
        Desktopabsoluteediting = 0x8004c000,

        Desktopabsoluteparsing = 0x80028000,

        Filesyspath = 0x80058000,

        Normaldisplay = 0,

        Parentrelative = 0x80080001,

        Parentrelativeediting = 0x80031001,

        Parentrelativeforaddressbar = 0x8007c001,

        Parentrelativeparsing = 0x80018001,

        Url = 0x80068000
    }
}