class HTTP::Redirector

def collect_cookies_from_request
  request_cookie_header = @request.headers["Cookie"]
  cookies =
    if request_cookie_header
      HTTP::Cookie.cookie_value_to_hash(request_cookie_header)
    else
      {}
    end
  cookies.each do |key, value|
    cookie_jar.add(HTTP::Cookie.new(key, value, :path => @request.uri.path, :domain => @request.host))
  end
end

def collect_cookies_from_response
  # Overwrite previous cookies
  @response.cookies.each do |cookie|
    if cookie.value == ""
      cookie_jar.delete(cookie)
    else
      cookie_jar.add(cookie)
    end
  end
  # I wish we could just do @response.cookes = cookie_jar
  cookie_jar.each do |cookie|
    @response.cookies.add(cookie)
  end
end

def cookie_jar
  # it seems that @response.cookies instance is reused between responses, so we have to "clone"
  @cookie_jar ||= HTTP::CookieJar.new
end

def endless_loop?
  2 <= @visited.count(@visited.last)
end

def initialize(opts = {})
  @strict      = opts.fetch(:strict, true)
  @max_hops    = opts.fetch(:max_hops, 5).to_i
  @on_redirect = opts.fetch(:on_redirect, nil)
end

def perform(request, response)
  @request  = request
  @response = response
  @visited  = []
  collect_cookies_from_request
  collect_cookies_from_response
  while REDIRECT_CODES.include? @response.status.code
    @visited << "#{@request.verb} #{@request.uri}"
    raise TooManyRedirectsError if too_many_hops?
    raise EndlessRedirectError  if endless_loop?
    @response.flush
    # XXX(ixti): using `Array#inject` to return `nil` if no Location header.
    @request = redirect_to(@response.headers.get(Headers::LOCATION).inject(:+))
    unless cookie_jar.empty?
      @request.headers.set(Headers::COOKIE, cookie_jar.cookies.map { |c| "#{c.name}=#{c.value}" }.join("; "))
    end
    @on_redirect.call @response, @request if @on_redirect.respond_to?(:call)
    @response = yield @request
    collect_cookies_from_response
  end
  @response
end

def redirect_to(uri)
  raise StateError, "no Location header in redirect" unless uri
  verb = @request.verb
  code = @response.status.code
  if UNSAFE_VERBS.include?(verb) && STRICT_SENSITIVE_CODES.include?(code)
    raise StateError, "can't follow #{@response.status} redirect" if @strict
    verb = :get
  end
  verb = :get if !SEE_OTHER_ALLOWED_VERBS.include?(verb) && 303 == code
  @request.redirect(uri, verb)
end

def too_many_hops?
  1 <= @max_hops && @max_hops < @visited.count
end