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

namespace Automata.Game;

/// <summary>
/// Win32 clipboard access without WinForms dependency.
/// </summary>
public static class ClipboardHelper
{
    private const int MaxRetries = 5;
    private const int RetryDelayMs = 30;

    public static string Read()
    {
        for (var attempt = 0; attempt < MaxRetries; attempt++)
        {
            if (ClipboardNative.OpenClipboard(IntPtr.Zero))
            {
                try
                {
                    var handle = ClipboardNative.GetClipboardData(ClipboardNative.CF_UNICODETEXT);
                    if (handle == IntPtr.Zero) return "";

                    var ptr = ClipboardNative.GlobalLock(handle);
                    if (ptr == IntPtr.Zero) return "";

                    try
                    {
                        return Marshal.PtrToStringUni(ptr) ?? "";
                    }
                    finally
                    {
                        ClipboardNative.GlobalUnlock(handle);
                    }
                }
                finally
                {
                    ClipboardNative.CloseClipboard();
                }
            }
            Thread.Sleep(RetryDelayMs);
        }
        return "";
    }

    public static void Write(string text)
    {
        for (var attempt = 0; attempt < MaxRetries; attempt++)
        {
            if (ClipboardNative.OpenClipboard(IntPtr.Zero))
            {
                try
                {
                    ClipboardNative.EmptyClipboard();
                    var bytes = Encoding.Unicode.GetBytes(text + "\0");
                    var hGlobal = ClipboardNative.GlobalAlloc(ClipboardNative.GMEM_MOVEABLE, (UIntPtr)bytes.Length);
                    if (hGlobal == IntPtr.Zero) return;

                    var ptr = ClipboardNative.GlobalLock(hGlobal);
                    if (ptr == IntPtr.Zero)
                    {
                        ClipboardNative.GlobalFree(hGlobal);
                        return;
                    }

                    try
                    {
                        Marshal.Copy(bytes, 0, ptr, bytes.Length);
                    }
                    finally
                    {
                        ClipboardNative.GlobalUnlock(hGlobal);
                    }

                    ClipboardNative.SetClipboardData(ClipboardNative.CF_UNICODETEXT, hGlobal);
                    return;
                }
                finally
                {
                    ClipboardNative.CloseClipboard();
                }
            }
            Thread.Sleep(RetryDelayMs);
        }
    }
}

internal static partial class ClipboardNative
{
    public const uint CF_UNICODETEXT = 13;
    public const uint GMEM_MOVEABLE = 0x0002;

    [LibraryImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static partial bool OpenClipboard(IntPtr hWndNewOwner);

    [LibraryImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static partial bool CloseClipboard();

    [LibraryImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static partial bool EmptyClipboard();

    [LibraryImport("user32.dll")]
    public static partial IntPtr GetClipboardData(uint uFormat);

    [LibraryImport("user32.dll")]
    public static partial IntPtr SetClipboardData(uint uFormat, IntPtr hMem);

    [LibraryImport("kernel32.dll")]
    public static partial IntPtr GlobalAlloc(uint uFlags, UIntPtr dwBytes);

    [LibraryImport("kernel32.dll")]
    public static partial IntPtr GlobalLock(IntPtr hMem);

    [LibraryImport("kernel32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static partial bool GlobalUnlock(IntPtr hMem);

    [LibraryImport("kernel32.dll")]
    public static partial IntPtr GlobalFree(IntPtr hMem);
}