Lithium/Lithium/AppPaths.cs

using System;
using System.IO;
using System.Runtime.InteropServices;

namespace Lua
{
    internal static class AppPaths
    {
        private const string ApplicationDirectoryName = "Lithium";

        public static string ExecutableDirectory => AppDomain.CurrentDomain.BaseDirectory;

        public static string UserDataDirectory => Path.Combine(
            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
            ApplicationDirectoryName);

        public static string WebViewUserDataDirectory => Path.Combine(UserDataDirectory, "WebView2");

        public static string WebViewLoaderDirectory => Path.Combine(
            ExecutableDirectory,
            "lib",
            "runtimes",
            GetRuntimeIdentifier(),
            "native");

        private static string GetRuntimeIdentifier()
        {
            switch (RuntimeInformation.ProcessArchitecture)
            {
                case Architecture.X64:
                    return "win-x64";
                case Architecture.Arm64:
                    return "win-arm64";
                default:
                    return "win-x86";
            }
        }

        public static string GetUserFilePath(string fileName)
        {
            Directory.CreateDirectory(UserDataDirectory);
            return Path.Combine(UserDataDirectory, fileName);
        }

        public static string GetReadableFilePath(string fileName)
        {
            string userPath = Path.Combine(UserDataDirectory, fileName);
            if (File.Exists(userPath))
                return userPath;

            string portablePath = Path.Combine(ExecutableDirectory, fileName);
            return File.Exists(portablePath) ? portablePath : null;
        }
    }
}