using System.Runtime.InteropServices;

namespace AxCopilot.Services;

internal static class ForegroundPasteHelper
{
    private const int SW_RESTORE = 9;
    private const uint INPUT_KEYBOARD = 1;
    private const uint KEYEVENTF_KEYUP = 0x0002;
    private const ushort VK_CONTROL = 0x11;
    private const ushort VK_V = 0x56;

    public static async Task<bool> RestoreWindowAsync(
        IntPtr hwnd,
        CancellationToken ct,
        int initialDelayMs = 220,
        int settleDelayMs = 60,
        int maxAttempts = 4)
    {
        if (hwnd == IntPtr.Zero || !IsWindow(hwnd))
            return false;

        await Task.Delay(initialDelayMs, ct);

        if (IsIconic(hwnd))
            ShowWindow(hwnd, SW_RESTORE);

        for (var attempt = 0; attempt < maxAttempts; attempt++)
        {
            uint currentThread = GetCurrentThreadId();
            uint targetThread = GetWindowThreadProcessId(hwnd, out _);
            var foreground = GetForegroundWindow();
            uint foregroundThread = foreground != IntPtr.Zero
                ? GetWindowThreadProcessId(foreground, out _)
                : 0;

            var attachedTarget = false;
            var attachedForeground = false;

            try
            {
                if (targetThread != 0 && targetThread != currentThread)
                {
                    AttachThreadInput(currentThread, targetThread, true);
                    attachedTarget = true;
                }

                if (foregroundThread != 0 && foregroundThread != currentThread && foregroundThread != targetThread)
                {
                    AttachThreadInput(currentThread, foregroundThread, true);
                    attachedForeground = true;
                }

                BringWindowToTop(hwnd);
                SetForegroundWindow(hwnd);
            }
            finally
            {
                if (attachedForeground)
                    AttachThreadInput(currentThread, foregroundThread, false);

                if (attachedTarget)
                    AttachThreadInput(currentThread, targetThread, false);
            }

            await Task.Delay(settleDelayMs, ct);

            if (GetForegroundWindow() == hwnd)
                return true;
        }

        return GetForegroundWindow() == hwnd;
    }

    public static async Task<bool> PasteClipboardAsync(
        IntPtr hwnd,
        CancellationToken ct,
        int initialDelayMs = 220)
    {
        var restored = await RestoreWindowAsync(hwnd, ct, initialDelayMs);
        if (!restored)
            return false;

        await Task.Delay(40, ct);
        SendCtrlV();
        return true;
    }

    private static void SendCtrlV()
    {
        var inputs = new INPUT[4];
        inputs[0] = new INPUT { Type = INPUT_KEYBOARD, Ki = new KEYBDINPUT { wVk = VK_CONTROL } };
        inputs[1] = new INPUT { Type = INPUT_KEYBOARD, Ki = new KEYBDINPUT { wVk = VK_V } };
        inputs[2] = new INPUT { Type = INPUT_KEYBOARD, Ki = new KEYBDINPUT { wVk = VK_V, dwFlags = KEYEVENTF_KEYUP } };
        inputs[3] = new INPUT { Type = INPUT_KEYBOARD, Ki = new KEYBDINPUT { wVk = VK_CONTROL, dwFlags = KEYEVENTF_KEYUP } };
        SendInput((uint)inputs.Length, inputs, Marshal.SizeOf<INPUT>());
    }

    [StructLayout(LayoutKind.Explicit, Size = 40)]
    private struct INPUT
    {
        [FieldOffset(0)] public uint Type;
        [FieldOffset(8)] public KEYBDINPUT Ki;
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct KEYBDINPUT
    {
        public ushort wVk;
        public ushort wScan;
        public uint dwFlags;
        public uint time;
        public IntPtr dwExtraInfo;
    }

    [DllImport("user32.dll")] private static extern bool SetForegroundWindow(IntPtr hWnd);
    [DllImport("user32.dll")] private static extern bool BringWindowToTop(IntPtr hWnd);
    [DllImport("user32.dll")] private static extern IntPtr GetForegroundWindow();
    [DllImport("user32.dll")] private static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint processId);
    [DllImport("user32.dll")] private static extern bool AttachThreadInput(uint idAttach, uint idAttachTo, [MarshalAs(UnmanagedType.Bool)] bool fAttach);
    [DllImport("user32.dll")] private static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
    [DllImport("user32.dll")] private static extern bool IsWindow(IntPtr hWnd);
    [DllImport("user32.dll")] private static extern bool IsIconic(IntPtr hWnd);
    [DllImport("kernel32.dll")] private static extern uint GetCurrentThreadId();
    [DllImport("user32.dll")] private static extern uint SendInput(uint nInputs, [MarshalAs(UnmanagedType.LPArray)] INPUT[] pInputs, int cbSize);
}