class Jets::Builders::Md5

def checksums
  @@checksums
end

def compute!
  stage_folders.each do |path|
    @@checksums[path] = dir(path)
  end
  @@checksums
end

def dir(short_path)
  path = "#{Jets.build_root}/#{short_path}"
  files = Dir["#{path}/**/*"]
  files.reject! { |f| File.directory?(f) }
       .reject! { |f| File.symlink?(f) }
  content = files.map do |f|
    Digest::MD5.file(f).to_s[0..7]
  end.join
  # The stage/code md5 sha depends on the other 'symlinked' folders.
  if short_path == "stage/code"
    content += @@checksums.values.join
  end
  md5 = Digest::MD5.new
  md5.update(content)
  md5.hexdigest.to_s[0..7]
end

def folder_exist?(folder)
  path = "#{Jets.build_root}/stage/#{folder}"
  File.directory?(path)
end

def stage_folders
  paths = []
  paths << "stage/opt" if folder_exist?("opt")
  paths << "stage/rack" if folder_exist?("rack")
  # Important to have stage/code at the end, since its md5 checksum depends
  # on the previous folders.
  paths << "stage/code"
  paths
end