using System.Formats.Tar;
using System.IO.Compression;

if (args.Length < 3)
{
    Console.Error.WriteLine("usage: Monitor.Tar <source-directory> <archive-path> <executable-relative-path>...");
    return 2;
}

string sourceDirectory = Path.GetFullPath(args[0]);
string archivePath = Path.GetFullPath(args[1]);
HashSet<string> executables = args.Skip(2).Select(path => path.Replace('\\', '/')).ToHashSet(StringComparer.Ordinal);
UnixFileMode executableMode = UnixFileMode.UserRead | UnixFileMode.UserWrite | UnixFileMode.UserExecute |
                              UnixFileMode.GroupRead | UnixFileMode.GroupExecute |
                              UnixFileMode.OtherRead | UnixFileMode.OtherExecute;
UnixFileMode regularMode = UnixFileMode.UserRead | UnixFileMode.UserWrite |
                           UnixFileMode.GroupRead | UnixFileMode.OtherRead;

Directory.CreateDirectory(Path.GetDirectoryName(archivePath)!);
using FileStream fileStream = File.Create(archivePath);
using GZipStream gzipStream = new(fileStream, CompressionLevel.Optimal, leaveOpen: true);
using TarWriter writer = new(gzipStream, TarEntryFormat.Pax, leaveOpen: true);

foreach (string filePath in Directory.EnumerateFiles(sourceDirectory, "*", SearchOption.AllDirectories))
{
    string relativePath = Path.GetRelativePath(sourceDirectory, filePath).Replace('\\', '/');
    PaxTarEntry entry = new(TarEntryType.RegularFile, relativePath)
    {
        Mode = executables.Contains(relativePath) ? executableMode : regularMode,
        DataStream = File.OpenRead(filePath)
    };
    using (entry.DataStream)
    {
        writer.WriteEntry(entry);
    }
}

return 0;