using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
using System.Text;

namespace FluidExplorer.Services.Shell;

/// <summary>
/// Windows 系统原版右键菜单（shell 的 IContextMenu）：
/// 就是资源管理器"显示更多选项"里那一套（含第三方扩展、发送到、打开方式、Windows Terminal 等），
/// 直接用系统实现，不自己造菜单项。
/// </summary>
public static class ShellContextMenu
{
    public static Task ShowAsync(IntPtr ownerHwnd, IReadOnlyList<string> paths, Windows.Graphics.PointInt32 screenPoint)
    {
        var tcs = new TaskCompletionSource(TaskCreationOptions.RunContinuationsAsynchronously);
        var dispatcher = Microsoft.UI.Dispatching.DispatcherQueue.GetForCurrentThread();

        void Run()
        {
            try
            {
                ShowCore(ownerHwnd, paths, screenPoint.X, screenPoint.Y);
                tcs.TrySetResult();
            }
            catch (Exception ex)
            {
                tcs.TrySetException(ex);
            }
        }

        if (dispatcher is null || dispatcher.HasThreadAccess) Run();
        else dispatcher.TryEnqueue(Run);
        return tcs.Task;
    }

    private static void ShowCore(IntPtr hwnd, IReadOnlyList<string> paths, int x, int y)
    {
        if (paths.Count == 0) return;

        var pidls = new List<IntPtr>();
        var allocated = new List<IntPtr>();
        IShellFolder? parentFolder = null;

        try
        {
            // 取第一条的父文件夹，作为构建 IContextMenu 的宿主（多选时要求同一父目录）
            var firstHr = SHParseDisplayName(paths[0], IntPtr.Zero, out var firstPidl, 0, out _);
            if (firstHr != 0 || firstPidl == IntPtr.Zero) return;
            allocated.Add(firstPidl);

            var bindHr = SHBindToParent(firstPidl, typeof(IShellFolder).GUID, out var folderObj, out var childPidl);
            if (bindHr != 0 || folderObj is null) return;
            parentFolder = (IShellFolder)folderObj;

            var childPidls = new List<IntPtr> { childPidl };
            for (var i = 1; i < paths.Count; i++)
            {
                if (SHParseDisplayName(paths[i], IntPtr.Zero, out var pidl, 0, out _) != 0 || pidl == IntPtr.Zero) continue;
                allocated.Add(pidl);
                var hr = SHBindToParent(pidl, typeof(IShellFolder).GUID, out var folder, out var child);
                if (hr != 0 || folder is null) continue;
                if (folder != parentFolder) continue;   // 不同目录的多选：忽略额外项（由上层逐个处理）
                childPidls.Add(child);
            }

            var iid = typeof(IContextMenu).GUID;
            var uiObjectHr = parentFolder.GetUIObjectOf(hwnd, (uint)childPidls.Count, childPidls.ToArray(), ref iid, IntPtr.Zero, out var contextMenuObj);
            if (uiObjectHr != 0 || contextMenuObj is null) return;

            var contextMenu = (IContextMenu)contextMenuObj;
            var contextMenu2 = contextMenuObj as IContextMenu2;
            var contextMenu3 = contextMenuObj as IContextMenu3;

            var hMenu = CreatePopupMenu();
            if (hMenu == IntPtr.Zero) return;

            try
            {
                const uint CMF_NORMAL = 0x00000000;
                const uint CMF_EXTENDEDVERBS = 0x00000100;
                var queryHr = contextMenu.QueryContextMenu(hMenu, 0, 1, 0x7FFF, CMF_NORMAL | CMF_EXTENDEDVERBS);
                if (queryHr < 0) return;

                // 系统菜单里"打开方式/发送到"等子菜单需要转发 owner-draw 消息
                using var hook = contextMenu2 is null && contextMenu3 is null
                    ? null
                    : new MenuMessageHook(hwnd, contextMenu2, contextMenu3);

                const uint TPM_RETURNCMD = 0x0100;
                const uint TPM_RIGHTBUTTON = 0x0002;
                var command = TrackPopupMenuEx(hMenu, TPM_RETURNCMD | TPM_RIGHTBUTTON, x, y, hwnd, IntPtr.Zero);
                if (command <= 0) return;

                var info = new CMINVOKECOMMANDINFOEX
                {
                    cbSize = Marshal.SizeOf<CMINVOKECOMMANDINFOEX>(),
                    fMask = 0x00004000 /*CMIC_MASK_UNICODE*/,
                    hwnd = hwnd,
                    lpVerb = (IntPtr)(command - 1),
                    lpVerbW = (IntPtr)(command - 1),
                    nShow = 1
                };

                var invokeHr = contextMenu.InvokeCommand(ref info);
                _ = invokeHr;
            }
            finally
            {
                DestroyMenu(hMenu);
            }
        }
        finally
        {
            foreach (var pidl in allocated) Marshal.FreeCoTaskMem(pidl);
            if (parentFolder is not null) Marshal.ReleaseComObject(parentFolder);
        }
    }

    /// <summary>把菜单的 owner-draw / init 消息转发给 IContextMenu2/3（子菜单才能正常展开）。</summary>
    private sealed class MenuMessageHook : IDisposable
    {
        private readonly IntPtr _hwnd;
        private readonly IContextMenu2? _menu2;
        private readonly IContextMenu3? _menu3;
        private readonly SubclassProc _proc;
        private readonly IntPtr _oldProc;

        public MenuMessageHook(IntPtr hwnd, IContextMenu2? menu2, IContextMenu3? menu3)
        {
            _hwnd = hwnd;
            _menu2 = menu2;
            _menu3 = menu3;
            _proc = HookProc;
            _oldProc = SetWindowLongPtr(hwnd, GWLP_WNDPROC, Marshal.GetFunctionPointerForDelegate(_proc));
        }

        private IntPtr HookProc(IntPtr hwnd, uint msg, IntPtr wParam, IntPtr lParam)
        {
            switch (msg)
            {
                case WM_INITMENUPOPUP:
                case WM_DRAWITEM:
                case WM_MEASUREITEM:
                case WM_MENUCHAR:
                    if (_menu3 is not null)
                    {
                        var handled = IntPtr.Zero;
                        if (_menu3.HandleMenuMsg2(msg, wParam, lParam, out handled) == 0 && handled != IntPtr.Zero) return handled;
                    }
                    else if (_menu2 is not null)
                    {
                        if (_menu2.HandleMenuMsg(msg, wParam, lParam) == 0) return IntPtr.Zero;
                    }
                    break;
            }
            return CallWindowProc(_oldProc, hwnd, msg, wParam, lParam);
        }

        public void Dispose()
        {
            if (_oldProc != IntPtr.Zero) SetWindowLongPtr(_hwnd, GWLP_WNDPROC, _oldProc);
        }
    }

    private const int GWLP_WNDPROC = -4;
    private const uint WM_INITMENUPOPUP = 0x0117;
    private const uint WM_DRAWITEM = 0x002B;
    private const uint WM_MEASUREITEM = 0x002C;
    private const uint WM_MENUCHAR = 0x0120;

    private delegate IntPtr SubclassProc(IntPtr hwnd, uint msg, IntPtr wParam, IntPtr lParam);

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    private struct CMINVOKECOMMANDINFOEX
    {
        public int cbSize;
        public uint fMask;
        public IntPtr hwnd;
        public IntPtr lpVerb;
        public IntPtr lpParameters;
        public IntPtr lpDirectory;
        public int nShow;
        public uint dwHotKey;
        public IntPtr hIcon;
        public IntPtr lpTitle;
        public IntPtr lpVerbW;
        public IntPtr lpParametersW;
        public IntPtr lpDirectoryW;
        public IntPtr lpTitleW;
        public POINT ptInvoke;
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct POINT
    {
        public int X;
        public int Y;
    }

    [ComImport]
    [Guid("000214E6-0000-0000-C000-000000000046")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IShellFolder
    {
        [PreserveSig] int ParseDisplayName(IntPtr hwnd, IntPtr pbc, [MarshalAs(UnmanagedType.LPWStr)] string pszDisplayName, out uint pchEaten, out IntPtr ppidl, ref uint pdwAttributes);
        [PreserveSig] int EnumObjects(IntPtr hwnd, uint grfFlags, out IntPtr ppenumIDList);
        [PreserveSig] int BindToObject(IntPtr pidl, IntPtr pbc, ref Guid riid, out IntPtr ppv);
        [PreserveSig] int BindToStorage(IntPtr pidl, IntPtr pbc, ref Guid riid, out IntPtr ppv);
        [PreserveSig] int CompareIDs(IntPtr lParam, IntPtr pidl1, IntPtr pidl2);
        [PreserveSig] int CreateViewObject(IntPtr hwndOwner, ref Guid riid, out IntPtr ppv);
        [PreserveSig] int GetAttributesOf(uint cidl, IntPtr[] apidl, ref uint rgfInOut);
        [PreserveSig] int GetUIObjectOf(IntPtr hwndOwner, uint cidl, IntPtr[] apidl, ref Guid riid, IntPtr rgfReserved, out object ppv);
        [PreserveSig] int GetDisplayNameOf(IntPtr pidl, uint uFlags, out IntPtr pName);
        [PreserveSig] int SetNameOf(IntPtr hwnd, IntPtr pidl, [MarshalAs(UnmanagedType.LPWStr)] string pszName, uint uFlags, out IntPtr ppidlOut);
    }

    [ComImport]
    [Guid("000214E4-0000-0000-C000-000000000046")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IContextMenu
    {
        [PreserveSig] int QueryContextMenu(IntPtr hmenu, uint indexMenu, uint idCmdFirst, uint idCmdLast, uint uFlags);
        [PreserveSig] int InvokeCommand(ref CMINVOKECOMMANDINFOEX pici);
        [PreserveSig] int GetCommandString(IntPtr idCmd, uint uType, IntPtr pReserved, StringBuilder pszName, uint cchMax);
    }

    [ComImport]
    [Guid("000214F4-0000-0000-C000-000000000046")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IContextMenu2
    {
        [PreserveSig] int QueryContextMenu(IntPtr hmenu, uint indexMenu, uint idCmdFirst, uint idCmdLast, uint uFlags);
        [PreserveSig] int InvokeCommand(ref CMINVOKECOMMANDINFOEX pici);
        [PreserveSig] int GetCommandString(IntPtr idCmd, uint uType, IntPtr pReserved, StringBuilder pszName, uint cchMax);
        [PreserveSig] int HandleMenuMsg(uint uMsg, IntPtr wParam, IntPtr lParam);
    }

    [ComImport]
    [Guid("BCFCE0A0-EC17-11D0-8D10-00A0C90F2719")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IContextMenu3
    {
        [PreserveSig] int QueryContextMenu(IntPtr hmenu, uint indexMenu, uint idCmdFirst, uint idCmdLast, uint uFlags);
        [PreserveSig] int InvokeCommand(ref CMINVOKECOMMANDINFOEX pici);
        [PreserveSig] int GetCommandString(IntPtr idCmd, uint uType, IntPtr pReserved, StringBuilder pszName, uint cchMax);
        [PreserveSig] int HandleMenuMsg(uint uMsg, IntPtr wParam, IntPtr lParam);
        [PreserveSig] int HandleMenuMsg2(uint uMsg, IntPtr wParam, IntPtr lParam, out IntPtr plResult);
    }

    [DllImport("shell32.dll", CharSet = CharSet.Unicode)]
    private static extern int SHParseDisplayName(string pszName, IntPtr pbc, out IntPtr ppidl, uint sfgaoIn, out uint psfgaoOut);

    [DllImport("shell32.dll", CharSet = CharSet.Unicode)]
    private static extern int SHBindToParent(IntPtr pidl, Guid riid, out object ppv, out IntPtr ppidlLast);

    [DllImport("user32.dll")] private static extern IntPtr CreatePopupMenu();
    [DllImport("user32.dll")] private static extern bool DestroyMenu(IntPtr hMenu);
    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    private static extern int TrackPopupMenuEx(IntPtr hMenu, uint fuFlags, int x, int y, IntPtr hwnd, IntPtr lptpm);

    [DllImport("user32.dll", EntryPoint = "SetWindowLongPtrW")]
    private static extern IntPtr SetWindowLongPtr(IntPtr hWnd, int nIndex, IntPtr dwNewLong);

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    private static extern IntPtr CallWindowProc(IntPtr lpPrevWndFunc, IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);
}