update-atom-packages.rb

#!/usr/bin/env ruby

PATH = File.expand_path('../..', __FILE__)
PACKAGES_TXT = File.join(PATH, "packages.txt")

def package_list
  "apm list --installed --bare --dev false"
end

def main
  installed = parse_package_list(`#{package_list}`)
  packages_txt = parse_package_list(File.read(PACKAGES_TXT))

  packages_to_remove(packages_txt, installed).each do |name, _|
    puts "Found package \"#{name}\" that is not in packages.txt."
    puts "If you installed this and want to keep it, type \"keep\": "
    line = readline.chomp
    next if line == "keep"

    system("apm uninstall #{name}")
  end

  # Install only updated or missing packages
  packages_to_install(packages_txt, installed).each do |name, version|
    system("apm install #{name}@#{version}")
  end

  # Write new packages.txt
  `#{package_list} > #{PACKAGES_TXT}`

  puts "Done!"
end

def packages_to_remove(packages_txt, installed)
  installed.reject { |name, _| packages_txt.key?(name) }
end

def packages_to_install(packages_txt, installed)
  packages_txt.select { |name, version|
    !installed.key?(name) ||
      Gem::Version.new(version) > Gem::Version.new(installed[name])
  }
end

def parse_package_list(list)
  Hash[list.lines
    .map(&:strip)
    .reject(&:empty?)
    .map { |line| parse_package(line.strip) }]
end

def parse_package(line)
  name, version = line.split("@")
  [name, version]
end

main if __FILE__ == $PROGRAM_NAME