using System.Runtime.InteropServices;
using FlaUI.Core.Input;
using FlaUI.Core.Definitions;
using FlaUI.UIA3;
using Windows.Win32;
using Windows.Win32.Foundation;
using Windows.Win32.UI.Accessibility;
using Windows.Win32.UI.Shell;
using Windows.Win32.UI.WindowsAndMessaging;
using WxAgent.Core;

namespace WxAgent.Windows;

public sealed record WechatTrayDiagnostic(int ToolbarCount, int IconCount, int WechatIconCount, string DetectionMethod = "MSAA");

internal static class WechatTray
{
    internal static bool TryActivateUia(UIA3Automation automation)
    {
        var regions = automation.GetDesktop().FindAllChildren(cf => cf.ByClassName("Shell_TrayWnd"))
            .SelectMany(window => window.FindAllDescendants(cf => cf.ByClassName("TrayNotifyWnd")));
        var matches = regions.SelectMany(region => region.FindAllDescendants(cf => cf.ByControlType(ControlType.Button)))
            .Where(icon => WechatLocators.IsWechatTrayName(icon.Name)
                && !icon.IsOffscreen && !icon.BoundingRectangle.IsEmpty).ToArray();
        if (matches.Length == 0) return false;
        if (matches.Length != 1)
            throw new WxAgentException(WxAgentErrorCode.InvalidOperationState, "Multiple WeChat notification icons found; refusing an ambiguous target.");
        var bounds = matches[0].BoundingRectangle;
        ActivateAt(new Point(bounds.Left + bounds.Width / 2, bounds.Top + bounds.Height / 2));
        return true;
    }

    // On Windows 10 the notification toolbar may expose no buttons through UIA3.
    // Use its public MSAA accessibility API, never Explorer process memory or tray callback message guesses.
    internal static unsafe WechatTrayDiagnostic Inspect(bool activate, CancellationToken cancellationToken)
    {
        var toolbars = new List<HWND>();
        PInvoke.EnumWindows((root, _) =>
        {
            var className = ReadClass(root);
            if (className is not ("Shell_TrayWnd" or "NotifyIconOverflowWindow")) return true;
            PInvoke.EnumChildWindows(root, (child, _) =>
            {
                if (ReadClass(child) == "ToolbarWindow32") toolbars.Add(child);
                return true;
            }, default);
            return true;
        }, default);
        var icons = 0;
        var matches = new List<(IAccessible Owner, object Child)>();
        var owners = new List<IAccessible>();
        try
        {
            foreach (var toolbar in toolbars)
            {
                cancellationToken.ThrowIfCancellationRequested();
                void* pointer;
                var hr = PInvoke.AccessibleObjectFromWindow(toolbar, 0xfffffffc, typeof(IAccessible).GUID, out pointer);
                if (hr.Value < 0 || pointer == null) continue;
                IAccessible owner;
                try { owner = (IAccessible)Marshal.GetObjectForIUnknown((nint)pointer); }
                finally { Marshal.Release((nint)pointer); }
                owners.Add(owner);
                var count = Math.Clamp(owner.accChildCount, 0, 256);
                var children = new object[count];
                PInvoke.AccessibleChildren(owner, 0, children, out var obtained);
                for (var index = 0; index < obtained; index++)
                {
                    cancellationToken.ThrowIfCancellationRequested();
                    var child = children[index];
                    if (child is not int) continue;
                    icons++;
                    var name = owner.get_accName(child);
                    string text;
                    try { text = name.ToString() ?? string.Empty; }
                    finally { if (name.Value != null) Marshal.FreeBSTR((nint)name.Value); }
                    if (WechatLocators.IsWechatTrayName(text)) matches.Add((owner, child));
                }
            }
            if (matches.Count == 0)
            {
                var nativeBounds = FindKnownIconBounds();
                if (activate)
                {
                    if (nativeBounds.Count != 1)
                        throw new WxAgentException(WxAgentErrorCode.ControlNotFound,
                            "No unique WeChat notification icon was found through accessibility or public shell metadata; no application was started.");
                    cancellationToken.ThrowIfCancellationRequested();
                    var bounds = nativeBounds[0];
                    ActivateAt(new Point(bounds.Left + bounds.Width / 2, bounds.Top + bounds.Height / 2));
                }
                return new WechatTrayDiagnostic(toolbars.Count, icons, nativeBounds.Count, "Shell_NotifyIconGetRect");
            }
            if (activate)
            {
                if (matches.Count != 1)
                    throw new WxAgentException(WxAgentErrorCode.ControlNotFound,
                        $"Expected one WeChat notification icon; found {matches.Count}. No application was started.");
                var match = matches[0];
                match.Owner.accLocation(out var left, out var top, out var width, out var height, match.Child);
                if (width <= 0 || height <= 0 || (Convert.ToInt32(match.Owner.get_accState(match.Child)) & 0x10000) != 0)
                    throw new WxAgentException(WxAgentErrorCode.ControlNotFound, "The WeChat tray icon is in the hidden overflow area; reveal it before restoring.");
                // Qt opens the original main window on a tray double-click, not MSAA's single default action.
                ActivateAt(new Point(left + width / 2, top + height / 2));
            }
            return new WechatTrayDiagnostic(toolbars.Count, icons, matches.Count);
        }
        finally
        {
            foreach (var owner in owners) Marshal.ReleaseComObject(owner);
        }
    }

    private static unsafe List<Rectangle> FindKnownIconBounds()
    {
        var result = new List<Rectangle>();
        foreach (var window in WechatNativeWindow.Enumerate().Where(window => window.ClassName == WechatLocators.TrayMessageWindowClass))
        {
            var identifier = new NOTIFYICONIDENTIFIER
            {
                cbSize = (uint)sizeof(NOTIFYICONIDENTIFIER),
                hWnd = new HWND((nint)window.Handle),
                uID = WechatLocators.TrayIconId
            };
            RECT bounds;
            if (PInvoke.Shell_NotifyIconGetRect(&identifier, &bounds).Value == 0
                && bounds.right > bounds.left && bounds.bottom > bounds.top)
                result.Add(Rectangle.FromLTRB(bounds.left, bounds.top, bounds.right, bounds.bottom));
        }
        return result;
    }

    private static void ActivateAt(Point point)
    {
        var hit = PInvoke.WindowFromPoint(point);
        var root = PInvoke.GetAncestor(hit, GET_ANCESTOR_FLAGS.GA_ROOT);
        if (!PInvoke.IsWindowVisible(root) || !WechatLocators.IsNotificationAreaRoot(ReadClass(root)))
            throw new WxAgentException(WxAgentErrorCode.InvalidOperationState,
                "The notification icon is obscured or its overflow panel is closed; refusing an unverified click.");
        Mouse.MoveTo(point);
        Mouse.DoubleClick(MouseButton.Left);
    }

    private static string ReadClass(HWND hwnd)
    {
        Span<char> text = stackalloc char[256];
        return new string(text[..PInvoke.GetClassName(hwnd, text)]);
    }
}

public static partial class WechatChatClient
{
    public static WechatTrayDiagnostic InspectTray(CancellationToken cancellationToken = default) =>
        WechatTray.Inspect(false, cancellationToken);
}