#! /usr/bin/env ruby
# frozen_string_literal: true

# Only use stdlib, no gems BS, no rails BS :)

dir_name = ARGV[0]
pcap_count = ARGV[1].to_i
compressed = ARGV[2].to_i

unless File.directory?(File.expand_path(dir_name))
  warn "Directory #{dir_name} does not exits. Exiting."
  exit 1
end

Dir.chdir(dir_name)

files_h = {}
Dir.foreach(dir_name) do |file|
  next if (file == '.') || (file == '..')

  # Compressed file modification time will be filename, for example:
  # capture00_1590423684.pcap.zst
  if compressed == 1 && file =~ /^capture(\d+)_(\d{10,})\.pcap\.zst$/
    timestamp = Regexp.last_match(2).to_i
    file_number = Regexp.last_match(1)
    files_h[timestamp] = file_number
  # Get uncompressed file modification time from file mtime itself
  elsif file =~ /^capture(\d+)$/
    file_number = Regexp.last_match(1)
    timestamp = File.mtime(file).to_i
    # p file_number, timestamp
    files_h[timestamp] = file_number

    if compressed == 1
      old_file = "capture#{file_number}"
      new_file = "capture#{file_number}_#{timestamp}.pcap.zst"
      File.delete(new_file) if File.exist?(new_file)
      system('/usr/bin/zstd', old_file, '-o', new_file, '--rm')
    end

  end
end

exit 0 if files_h.empty?

new_number = pcap_count - 1
zero_count = new_number.to_s.length
files = files_h.sort_by { |k, _v| -k }

files.each do |timestamp, number|

  old_prefix = "capture#{number}"
  new_number_string = format "%0#{zero_count}d", new_number
  new_prefix = "capture#{new_number_string}"

  if compressed == 1
    file_suffix = "_#{timestamp}.pcap.zst"
  else
    file_suffix = ''
  end

  file_old = old_prefix + file_suffix
  file_new = new_prefix + file_suffix

  if File.exist?(file_old)
    if File.exist?(file_new)
      File.rename(file_new, 'temp_file')
      File.rename(file_old, file_new)
      File.rename('temp_file', file_old)
    else
      File.rename(file_old, file_new)
    end
  end

  new_number -= 1
  break if new_number < 0
end