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

namespace Notify.Interop;

/// <summary>
/// Windows Terminal 标签页的捕获与切换
///
/// save 时记录当前选中标签的 RuntimeId，点击通知激活窗口后再据此切回该标签
/// 全程走源生成 COM（GeneratedComInterface），保证 NativeAOT 兼容
/// vtable 顺序与 GUID 均取自 Windows SDK UIAutomationClient.h
/// </summary>
public static partial class WinTerminalTabs
{
    private const string WtClass = "CASCADIA_HOSTING_WINDOW_CLASS";

    private const int TreeScopeDescendants = 4;
    private const int ControlTypePropertyId = 30003;
    private const int IsSelectedPropertyId = 30079;
    private const int TabItemControlTypeId = 50019;
    private const int SelectionItemPatternId = 10010;

    private const int CLSCTX_INPROC_SERVER = 1;

    private static readonly StrategyBasedComWrappers ComWrappers = new();
    private static IUIAutomation? _uia;
    private static bool _initTried;

    public static bool IsWindowsTerminal(IntPtr hwnd) =>
        hwnd != IntPtr.Zero && Win32.GetClassNameOf(hwnd) == WtClass;

    // 返回当前选中标签的 RuntimeId 串，失败返回空串
    public static string GetSelectedTabRuntimeId(IntPtr hwnd)
    {
        try
        {
            var uia = EnsureUia();
            if (uia is null)
            {
                return "";
            }

            var root = uia.ElementFromHandle(hwnd);
            var cond = uia.CreateTrueCondition();
            var all = root.FindAll(TreeScopeDescendants, cond);

            var count = all.Length();
            for (var i = 0; i < count; i++)
            {
                var el = all.GetElement(i);
                if (GetIntProperty(el, ControlTypePropertyId) != TabItemControlTypeId)
                {
                    continue;
                }

                if (GetBoolProperty(el, IsSelectedPropertyId))
                {
                    return RuntimeIdOf(el);
                }
            }
        }
        catch
        {
            // 任何 COM 异常退回空串
        }

        return "";
    }

    // 在已激活的 WT 窗口里找到匹配 RuntimeId 的标签并选中
    public static bool SelectTab(IntPtr hwnd, string runtimeId)
    {
        if (string.IsNullOrEmpty(runtimeId))
        {
            return false;
        }

        try
        {
            var uia = EnsureUia();
            if (uia is null)
            {
                return false;
            }

            var root = uia.ElementFromHandle(hwnd);
            var cond = uia.CreateTrueCondition();
            var all = root.FindAll(TreeScopeDescendants, cond);

            var count = all.Length();
            for (var i = 0; i < count; i++)
            {
                var el = all.GetElement(i);
                if (GetIntProperty(el, ControlTypePropertyId) != TabItemControlTypeId)
                {
                    continue;
                }

                if (RuntimeIdOf(el) != runtimeId)
                {
                    continue;
                }

                var pattern = el.GetCurrentPattern(SelectionItemPatternId);
                if (pattern is null)
                {
                    return false;
                }

                pattern.Select();
                return true;
            }
        }
        catch
        {
            // 切换失败不影响窗口已被激活
        }

        return false;
    }

    private static IUIAutomation? EnsureUia()
    {
        if (_initTried)
        {
            return _uia;
        }

        _initTried = true;
        try
        {
            var clsid = new Guid("ff48dba4-60ef-4201-aa87-54103eef594e");
            var iid = typeof(IUIAutomation).GUID;
            var hr = CoCreateInstance(ref clsid, IntPtr.Zero, CLSCTX_INPROC_SERVER, ref iid, out var ptr);
            if (hr >= 0 && ptr != IntPtr.Zero)
            {
                _uia = (IUIAutomation)ComWrappers.GetOrCreateObjectForComInstance(ptr, CreateObjectFlags.None);
                Marshal.Release(ptr);
            }
        }
        catch
        {
            _uia = null;
        }

        return _uia;
    }

    private static int GetIntProperty(IUIAutomationElement el, int propertyId)
    {
        var v = el.GetCurrentPropertyValue(propertyId);
        return v.lVal;
    }

    private static bool GetBoolProperty(IUIAutomationElement el, int propertyId)
    {
        var v = el.GetCurrentPropertyValue(propertyId);
        return v.boolVal != 0;
    }

    // RuntimeId 是一个 int 数组（SAFEARRAY），拼成点分串用于比较
    private static string RuntimeIdOf(IUIAutomationElement el)
    {
        var psa = el.GetRuntimeId();
        if (psa == IntPtr.Zero)
        {
            return "";
        }

        try
        {
            if (SafeArrayGetLBound(psa, 1, out var lb) < 0 || SafeArrayGetUBound(psa, 1, out var ub) < 0)
            {
                return "";
            }

            var sb = new StringBuilder();
            for (var idx = lb; idx <= ub; idx++)
            {
                var i = idx;
                if (SafeArrayGetElement(psa, ref i, out var val) < 0)
                {
                    return "";
                }

                if (sb.Length > 0)
                {
                    sb.Append('.');
                }

                sb.Append(val);
            }

            return sb.ToString();
        }
        finally
        {
            SafeArrayDestroy(psa);
        }
    }

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

    [LibraryImport("oleaut32.dll")]
    private static partial int SafeArrayGetLBound(IntPtr psa, uint nDim, out int plLbound);

    [LibraryImport("oleaut32.dll")]
    private static partial int SafeArrayGetUBound(IntPtr psa, uint nDim, out int plUbound);

    [LibraryImport("oleaut32.dll")]
    private static partial int SafeArrayGetElement(IntPtr psa, ref int rgIndices, out int pv);

    [LibraryImport("oleaut32.dll")]
    private static partial int SafeArrayDestroy(IntPtr psa);
}

// VARIANT 的最小化布局（x64 为 24 字节），只读 VT_I4 / VT_BOOL
[StructLayout(LayoutKind.Explicit, Size = 24)]
internal struct VARIANT
{
    [FieldOffset(0)]
    public ushort vt;

    [FieldOffset(8)]
    public int lVal;

    [FieldOffset(8)]
    public short boolVal;
}

[GeneratedComInterface]
[Guid("30cbe57d-d9d0-452a-ab13-7ac5ac4825ee")]
internal partial interface IUIAutomation
{
    void _CompareElements();
    void _CompareRuntimeIds();
    void _GetRootElement();
    IUIAutomationElement ElementFromHandle(IntPtr hwnd);
    void _ElementFromPoint();
    void _GetFocusedElement();
    void _GetRootElementBuildCache();
    void _ElementFromHandleBuildCache();
    void _ElementFromPointBuildCache();
    void _GetFocusedElementBuildCache();
    void _CreateTreeWalker();
    void _get_ControlViewWalker();
    void _get_ContentViewWalker();
    void _get_RawViewWalker();
    void _get_RawViewCondition();
    void _get_ControlViewCondition();
    void _get_ContentViewCondition();
    void _CreateCacheRequest();
    IUIAutomationCondition CreateTrueCondition();
}

[GeneratedComInterface]
[Guid("d22108aa-8ac5-49a5-837b-37bbb3d7591e")]
internal partial interface IUIAutomationElement
{
    void _SetFocus();
    IntPtr GetRuntimeId();
    void _FindFirst();
    IUIAutomationElementArray FindAll(int scope, IUIAutomationCondition condition);
    void _FindFirstBuildCache();
    void _FindAllBuildCache();
    void _BuildUpdatedCache();
    VARIANT GetCurrentPropertyValue(int propertyId);
    void _GetCurrentPropertyValueEx();
    void _GetCachedPropertyValue();
    void _GetCachedPropertyValueEx();
    void _GetCurrentPatternAs();
    void _GetCachedPatternAs();
    [return: MarshalUsing(typeof(UniqueComInterfaceMarshaller<IUIAutomationSelectionItemPattern>))]
    IUIAutomationSelectionItemPattern? GetCurrentPattern(int patternId);
}

[GeneratedComInterface]
[Guid("14314595-b4bc-4055-95f2-58f2e42c9855")]
internal partial interface IUIAutomationElementArray
{
    int Length();
    IUIAutomationElement GetElement(int index);
}

[GeneratedComInterface]
[Guid("352ffba8-0973-437c-a61f-f64cafd81df9")]
internal partial interface IUIAutomationCondition
{
}

[GeneratedComInterface]
[Guid("a8efa66a-0fda-421a-9194-38021f3578ea")]
internal partial interface IUIAutomationSelectionItemPattern
{
    void Select();
}