module Rack::Response::Helpers

def accepted?;            status == 202;                        end

def add_header(key, value)
  raise ArgumentError unless key.is_a?(String)
  if value.nil?
    return get_header(key)
  end
  value = value.to_s
  if header = get_header(key)
    if header.is_a?(Array)
      header << value
    else
      set_header(key, [header, value])
    end
  else
    set_header(key, value)
  end
end

def append(chunk)
  chunk = chunk.dup unless chunk.frozen?
  @body << chunk
  if @length
    @length += chunk.bytesize
  elsif @buffered
    @length = chunk.bytesize
  end
  return chunk
end

def bad_request?;         status == 400;                        end

def buffered_body!
  if @buffered.nil?
    if @body.is_a?(Array)
      # The user supplied body was an array:
      @body = @body.compact
      @length = @body.sum{|part| part.bytesize}
      @buffered = true
    elsif @body.respond_to?(:each)
      # Turn the user supplied body into a buffered array:
      body = @body
      @body = Array.new
      @buffered = true
      body.each do |part|
        @writer.call(part.to_s)
      end
      body.close if body.respond_to?(:close)
    else
      # We don't know how to buffer the user-supplied body:
      @buffered = false
    end
  end
  return @buffered
end

def cache!(duration = 3600, directive: "public")
  unless headers[CACHE_CONTROL] =~ /no-cache/
    set_header CACHE_CONTROL, "#{directive}, max-age=#{duration}"
    set_header EXPIRES, (Time.now + duration).httpdate
  end
end

def cache_control
  get_header CACHE_CONTROL
end

def cache_control=(value)
  set_header CACHE_CONTROL, value
end

def client_error?;        status >= 400 && status < 500;        end

def content_length
  cl = get_header CONTENT_LENGTH
  cl ? cl.to_i : cl
end

def content_type
  get_header CONTENT_TYPE
end

def content_type=(content_type)
  set_header CONTENT_TYPE, content_type
end

def created?;             status == 201;                        end

def delete_cookie(key, value = {})
  set_header(SET_COOKIE,
    Utils.delete_set_cookie_header!(
      get_header(SET_COOKIE), key, value
    )
  )
end

def do_not_cache!
  set_header CACHE_CONTROL, "no-cache, must-revalidate"
  set_header EXPIRES, Time.now.httpdate
end

def etag
  get_header ETAG
end

def etag=(value)
  set_header ETAG, value
end

def forbidden?;           status == 403;                        end

def include?(header)
  has_header?(header)
end

def informational?;       status >= 100 && status < 200;        end

def invalid?;             status < 100 || status >= 600;        end

def location
  get_header "location"
end

def location=(location)
  set_header "location", location
end

def media_type
  MediaType.type(content_type)
end

def media_type_params
  MediaType.params(content_type)
end

def method_not_allowed?;  status == 405;                        end

def moved_permanently?;   status == 301;                        end

def no_content?;          status == 204;                        end

def not_acceptable?;      status == 406;                        end

def not_found?;           status == 404;                        end

def ok?;                  status == 200;                        end

def precondition_failed?; status == 412;                        end

def redirect?;            [301, 302, 303, 307, 308].include? status; end

def redirection?;         status >= 300 && status < 400;        end

def request_timeout?;     status == 408;                        end

def server_error?;        status >= 500 && status < 600;        end

def set_cookie(key, value)
  add_header SET_COOKIE, Utils.set_cookie_header(key, value)
end

def set_cookie_header
  get_header SET_COOKIE
end

def set_cookie_header=(value)
  set_header SET_COOKIE, value
end

def successful?;          status >= 200 && status < 300;        end

def unauthorized?;        status == 401;                        end

def unprocessable?;       status == 422;                        end