module Sprockets::Mime

def read_file(filename, content_type = nil)
  data = File.open(filename, 'rb') { |f| f.read }
  if type = mime_types[content_type]
    if charset = type[:charset]
      data = charset.call(data).encode(Encoding::UTF_8)
    end
  end
  data
end

def read_input(input)
  read_file(input[:filename], input[:content_type])
end

def register_encoding(name, encode)
  mutate_config(:encodings) do |encodings|
    encodings.merge(name.to_s => encode)
  end
end

def register_mime_type(mime_type, options = {})
  # Legacy extension argument, will be removed from 4.x
  if options.is_a?(String)
    options = { extensions: [options] }
  end
  extnames = Array(options[:extensions]).map { |extname|
    Sprockets::Utils.normalize_extension(extname)
  }
  charset = options[:charset]
  charset ||= EncodingUtils::DETECT if mime_type.start_with?('text/')
  mutate_config(:mime_exts) do |mime_exts|
    extnames.each do |extname|
      mime_exts[extname] = mime_type
    end
    mime_exts
  end
  mutate_config(:mime_types) do |mime_types|
    type = { extensions: extnames }
    type[:charset] = charset if charset
    mime_types.merge(mime_type => type)
  end
end

def unwrap_encoding_processors(encoding)
  processors = []
  if encoder = self.encodings[encoding]
    processors << lambda do |input|
      { data: encoder.call(input[:data]), encoding: encoding }
    end
  end
  processors
end