using System;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.Marshalling;

namespace Notify.Interop;

/// <summary>
/// 把窗口"钉"到所有虚拟桌面（Win+Tab 切桌面后仍可见）
///
/// 走 Windows **未公开** 的 COM 接口：ImmersiveShell -> IApplicationViewCollection
/// -> IVirtualDesktopPinnedApps.PinView。GUID/方法顺序随 build 变化，这里用 Win11 24H2
/// (build 26100) 的定义（来自 MScholtes/VirtualDesktop），实测在 26200 上 GUID 仍匹配
///
/// 关键点：IApplicationView 是 IInspectable，而现代 .NET 不支持 IInspectable 封送，
/// 因此这里把 view 当作 **裸 IntPtr** 在 GetViewForHwnd / PinView 之间传递，绕开封送
/// 任何一步失败都被吞掉，退回"仅当前桌面显示"
///
/// AOT 说明：接口用源生成 COM（GeneratedComInterface），ImmersiveShell 用
/// CoCreateInstance 直接拿 IUnknown 指针并经 StrategyBasedComWrappers 包装，
/// 不再依赖内置 COM 封送（NativeAOT 下内置封送会被裁剪）
/// </summary>
public static partial class VirtualDesktopPinner
{
    private static readonly StrategyBasedComWrappers ComWrappers = new();

    private static bool _initialized;
    private static bool _available;
    private static IApplicationViewCollection? _views;
    private static IVirtualDesktopPinnedApps? _pinned;

    /// <summary>
    /// 最近一次失败的诊断信息（临时排查用）
    /// </summary>
    public static string LastError { get; private set; } = "";

    /// <summary>
    /// 尝试把指定窗口钉到所有桌面；返回是否成功
    /// </summary>
    public static bool TryPin(IntPtr hwnd)
    {
        if (hwnd == IntPtr.Zero)
        {
            LastError = "hwnd=0";
            return false;
        }

        try
        {
            EnsureInit();
            if (!_available || _views is null || _pinned is null)
            {
                LastError = "init failed: " + LastError;
                return false;
            }

            var view = IntPtr.Zero;
            try
            {
                _views.GetViewForHwnd(hwnd, out view);
                if (view == IntPtr.Zero)
                {
                    LastError = "GetViewForHwnd returned null";
                    return false;
                }

                _pinned.PinView(view);
                return true;
            }
            catch (Exception ex)
            {
                LastError = "pin: " + ex.GetType().Name + " 0x" + ex.HResult.ToString("X8") + " " + ex.Message;
                return false;
            }
            finally
            {
                if (view != IntPtr.Zero)
                {
                    Marshal.Release(view); // GetViewForHwnd 返回的指针已 AddRef
                }
            }
        }
        catch (Exception ex)
        {
            LastError = "outer: " + ex.GetType().Name + " " + ex.Message;
            return false;
        }
    }

    private static void EnsureInit()
    {
        if (_initialized)
        {
            return;
        }

        _initialized = true;
        var shellPtr = IntPtr.Zero;
        try
        {
            // 用 CoCreateInstance 直接拿 ImmersiveShell 的 IServiceProvider10 指针
            // 等价于经典写法 Activator.CreateInstance(GetTypeFromCLSID(...)) 但 AOT 友好
            var clsid = CLSID_ImmersiveShell;
            var iidServiceProvider = IID_IServiceProvider10;
            // ImmersiveShell 是本地服务器，必须用 CLSCTX_LOCAL_SERVER
            // 仅传 INPROC_SERVER 会得到 0x80040154 REGDB_E_CLASSNOTREG
            var hr = CoCreateInstance(ref clsid, IntPtr.Zero, CLSCTX_LOCAL_SERVER, ref iidServiceProvider, out shellPtr);
            if (hr < 0 || shellPtr == IntPtr.Zero)
            {
                throw new InvalidOperationException("CoCreateInstance(ImmersiveShell) 0x" + hr.ToString("X8"));
            }

            var shell = (IServiceProvider10)ComWrappers.GetOrCreateObjectForComInstance(shellPtr, CreateObjectFlags.None);

            var viewCollectionGuid = IID_IApplicationViewCollection;
            var viewsPtr = shell.QueryService(ref viewCollectionGuid, ref viewCollectionGuid);
            _views = WrapRequired<IApplicationViewCollection>(viewsPtr, "IApplicationViewCollection");

            var pinnedGuid = IID_IVirtualDesktopPinnedApps;
            var clsidPinned = CLSID_VirtualDesktopPinnedApps;
            var pinnedPtr = shell.QueryService(ref clsidPinned, ref pinnedGuid);
            _pinned = WrapRequired<IVirtualDesktopPinnedApps>(pinnedPtr, "IVirtualDesktopPinnedApps");

            _available = true;
        }
        catch (Exception ex)
        {
            _available = false;
            LastError = "EnsureInit: " + ex.GetType().Name + " 0x" + ex.HResult.ToString("X8") + " " + ex.Message;
        }
        finally
        {
            if (shellPtr != IntPtr.Zero)
            {
                // GetOrCreateObjectForComInstance 持有了自己的引用，释放本地这一份
                Marshal.Release(shellPtr);
            }
        }
    }

    // 把 QueryService 返回的裸 IUnknown 指针包装成托管 RCW，并释放本地引用
    private static T WrapRequired<T>(IntPtr unknown, string name)
    {
        if (unknown == IntPtr.Zero)
        {
            throw new InvalidOperationException("QueryService(" + name + ") 返回 null");
        }

        try
        {
            return (T)ComWrappers.GetOrCreateObjectForComInstance(unknown, CreateObjectFlags.None);
        }
        finally
        {
            Marshal.Release(unknown);
        }
    }

    private const int CLSCTX_LOCAL_SERVER = 4;

    // --- CLSIDs / IIDs ---
    private static readonly Guid CLSID_ImmersiveShell = new("C2F03A33-21F5-47FA-B4BB-156362A2F239");
    private static readonly Guid CLSID_VirtualDesktopPinnedApps = new("B5A399E7-1C87-46B8-88E9-FC5747B171BD");
    private static readonly Guid IID_IServiceProvider10 = new("6D5140C1-7436-11CE-8034-00AA006009FA");
    private static readonly Guid IID_IApplicationViewCollection = new("1841C6D7-4F9D-42C0-AF41-8747538F10E5");
    private static readonly Guid IID_IVirtualDesktopPinnedApps = new("4CE81583-1E4C-4632-A621-07A53543148F");

    [LibraryImport("ole32.dll")]
    private static partial int CoCreateInstance(
        ref Guid rclsid,
        IntPtr pUnkOuter,
        int dwClsContext,
        ref Guid riid,
        out IntPtr ppv);
}

// ImmersiveShell 的 IServiceProvider（与系统 IServiceProvider 不同）
// QueryService 返回裸 IUnknown 指针（nint），由调用方用 ComWrappers 包装
[GeneratedComInterface]
[Guid("6D5140C1-7436-11CE-8034-00AA006009FA")]
internal partial interface IServiceProvider10
{
    IntPtr QueryService(ref Guid service, ref Guid riid);
}

// 只声明到 GetViewForHwnd（第 4 个方法）；view 用 IntPtr，避免 IInspectable 封送
[GeneratedComInterface]
[Guid("1841C6D7-4F9D-42C0-AF41-8747538F10E5")]
internal partial interface IApplicationViewCollection
{
    int GetViews(out IntPtr array);
    int GetViewsByZOrder(out IntPtr array);
    int GetViewsByAppUserModelId([MarshalAs(UnmanagedType.LPWStr)] string id, out IntPtr array);
    int GetViewForHwnd(IntPtr hwnd, out IntPtr view);
}

// view 参数同样用 IntPtr
[GeneratedComInterface]
[Guid("4CE81583-1E4C-4632-A621-07A53543148F")]
internal partial interface IVirtualDesktopPinnedApps
{
    [return: MarshalAs(UnmanagedType.Bool)]
    bool IsAppIdPinned([MarshalAs(UnmanagedType.LPWStr)] string appId);
    void PinAppID([MarshalAs(UnmanagedType.LPWStr)] string appId);
    void UnpinAppID([MarshalAs(UnmanagedType.LPWStr)] string appId);
    [return: MarshalAs(UnmanagedType.Bool)]
    bool IsViewPinned(IntPtr applicationView);
    void PinView(IntPtr applicationView);
    void UnpinView(IntPtr applicationView);
}