#!/usr/bin/env ruby


require 'open-uri'
require 'zip'       # gem install rubyzip
require 'stringio'
require 'fileutils'
require 'uri'
require 'xz'        # gem install ruby-xz

url = 'https://artur.gurgul.pro/static/vms/debian.ext2.img.zip'
# 'https://artur.gurgul.pro/static/vms/linux-v1.zip'
# debian.ext2.img.zip	debian.ext4.img.zip  linux-v1.zip

# sudo fdisk -l debian.img
# [sudo] password for artur:
# Disk debian.img: 4 GiB, 4294967296 bytes, 8388608 sectors
# Units: sectors of 1 * 512 = 512 bytes
# Sector size (logical/physical): 512 bytes / 512 bytes
# I/O size (minimum/optimal): 512 bytes / 512 bytes
# Disklabel type: dos
# Disk identifier: 0x878d05dc
#
# Device      Boot Start     End Sectors Size Id Type
# debian.img1 *     2048 8386559 8384512   4G 83 Linux
# artur@gurgul.xyz ~/vm ➜ sudo mount -o loop,offset=1048576 debian.img /mnt
# 1048576 = 512 * 2048
# sudo tar --xattrs --acls --numeric-owner -cpf - -C /mnt/diskimg . | xz -T0 > disk-backup.tar.xz
# To preserve all metadata, ownership, permissions, symlinks, devices, etc., use tar with --xattrs, --numeric-owner
#   -cpf - → write tar to stdout
#   -C /mnt/diskimg . → change directory so root of the archive matches root of the image
#   xz -T0 → compress using all CPU cores

# https://chatgpt.com/c/688b32da-5e14-8327-9abc-b83a44252c05
# compare for differences
# sudo diff -r /mnt/diskimg /tmp/old

# Determine file extension
ext = File.extname(URI.parse(url).path)

# Open remote stream
URI.open(url) do |remote_file|
  case ext
  when '.zip'
    puts "Processing ZIP file..."

    buffer = remote_file.read
    Zip::File.open_buffer(StringIO.new(buffer)) do |zip_file|
      zip_file.each do |entry|
        puts "Extracting #{entry.name}..."
        target_path = File.join(Dir.pwd, entry.name)
        FileUtils.mkdir_p(File.dirname(target_path))
        entry.extract(target_path) { true }  # Overwrite if exists
      end
    end

  when '.xz'
    puts "Processing XZ file..."

    # Use XZ::StreamReader to decompress on-the-fly
    xz_reader = XZ::StreamReader.new(remote_file)

    # Assume .xz contains a single file; decide on output name
    output_filename = File.basename(url, '.xz')
    output_path = File.join(Dir.pwd, output_filename)

    File.open(output_path, 'wb') do |out|
      IO.copy_stream(xz_reader, out)
    end

    puts "Decompressed to #{output_path}"

  else
    puts "Unsupported file extension: #{ext}"
  end
end