class Sprockets::Preprocessors::DefaultSourceMap

def call(input)
  result        = { data: input[:data] }
  map           = input[:metadata][:map]
  filename      = input[:filename]
  load_path     = input[:load_path]
  lines         = input[:data].lines.count
  basename      = File.basename(filename)
  mime_exts     = input[:environment].config[:mime_exts]
  pipeline_exts = input[:environment].config[:pipeline_exts]
  if map.nil? || map.empty?
    result[:map] = {
      "version"   => 3,
      "file"      => PathUtils.split_subpath(load_path, filename),
      "mappings"  => default_mappings(lines),
      "sources"   => [PathUtils.set_pipeline(basename, mime_exts, pipeline_exts, :source)],
      "names"     => []
    }
  end
  return result
end