class ActionDispatch::RequestEncoder

def self.encoder(name)
  @encoders[name] || @encoders[:identity]
end

def self.parser(content_type)
  type = Mime::Type.lookup(content_type).ref if content_type
  encoder(type).response_parser
end

def self.register_encoder(mime_name, param_encoder: nil, response_parser: nil)
  @encoders[mime_name] = new(mime_name, param_encoder, response_parser)
end

def accept_header
  @mime.to_s
end

def content_type
  @mime.to_s
end

def encode_params(params)
  @param_encoder.call(params) if params
end

def initialize(mime_name, param_encoder, response_parser)
  @mime = Mime[mime_name]
  unless @mime
    raise ArgumentError, "Can't register a request encoder for " \
      "unregistered MIME Type: #{mime_name}. See `Mime::Type.register`."
  end
  @response_parser = response_parser || -> body { body }
  @param_encoder   = param_encoder   || :"to_#{@mime.symbol}".to_proc
end