// SPDX-License-Identifier: GPL-3.0-only
using System;
using System.Collections.Generic;
using System.Reflection;
using System.Runtime.InteropServices;

namespace BlockMelonLoader
{
    public static class LoaderGuard
    {
        public static void EnsureAllowed(string modName)
        {
            EnsureAllowed(modName, AppDomain.CurrentDomain.GetAssemblies(), ShowAlert, Environment.FailFast);
        }

        internal static void EnsureAllowed(string modName, IEnumerable<Assembly> assemblies,
            Action<string> showAlert, Action<string> terminate)
        {
            foreach (var assembly in assemblies)
            {
                if (!string.Equals(assembly.GetName().Name, "MelonLoader", StringComparison.OrdinalIgnoreCase))
                    continue;

                var message = modName + " cannot run while MelonLoader is active.\n\n"
                    + "Remove MelonLoader and install this mod using Unity Mod Manager.\n\n"
                    + "The game will close after this message.";
                // Loader exception handlers can swallow a thrown exception, so termination
                // must happen even if the native dialog fails.
                try { showAlert(message); }
                finally { terminate(message); }
                return;
            }
        }

        private static void ShowAlert(string message)
        {
            Console.Error.WriteLine(message);
            if (Environment.OSVersion.Platform == PlatformID.Win32NT)
                MessageBoxW(IntPtr.Zero, message, "Unsupported mod loader", 0x10 | 0x10000);
        }

        [DllImport("user32.dll", CharSet = CharSet.Unicode, ExactSpelling = true)]
        private static extern int MessageBoxW(IntPtr window, string text, string caption, uint type);
    }
}