require 'digest/md5'

module ActionController # :nodoc:
  # Represents an HTTP response generated by a controller action. One can use
  # an ActionController::Response object to retrieve the current state
  # of the response, or customize the response. An Response object can
  # either represent a "real" HTTP response (i.e. one that is meant to be sent
  # back to the web browser) or a test response (i.e. one that is generated
  # from integration tests). See CgiResponse and TestResponse, respectively.
  #
  # Response is mostly a Ruby on Rails framework implement detail, and
  # should never be used directly in controllers. Controllers should use the
  # methods defined in ActionController::Base instead. For example, if you want
  # to set the HTTP response's content MIME type, then use
  # ActionControllerBase#headers instead of Response#headers.
  #
  # Nevertheless, integration tests may want to inspect controller responses in
  # more detail, and that's when Response can be useful for application
  # developers. Integration test methods such as
  # ActionController::Integration::Session#get and
  # ActionController::Integration::Session#post return objects of type
  # TestResponse (which are of course also of type Response).
  #
  # For example, the following demo integration "test" prints the body of the
  # controller response to the console:
  #
  #  class DemoControllerTest < ActionController::IntegrationTest
  #    def test_print_root_path_to_console
  #      get('/')
  #      puts @response.body
  #    end
  #  end
  class Response < Rack::Response
    DEFAULT_HEADERS = { "Cache-Control" => "no-cache" }
    attr_accessor :request

    attr_accessor :session, :assigns, :template, :layout
    attr_accessor :redirected_to, :redirected_to_method_params

    delegate :default_charset, :to => 'ActionController::Base'

    def initialize
      @status = 200
      @header = Rack::Utils::HeaderHash.new(DEFAULT_HEADERS)

      @writer = lambda { |x| @body << x }
      @block = nil

      @body = "",
      @session = []
      @assigns = []
    end

    def location; headers['Location'] end
    def location=(url) headers['Location'] = url end


    # Sets the HTTP response's content MIME type. For example, in the controller
    # you could write this:
    #
    #  response.content_type = "text/plain"
    #
    # If a character set has been defined for this response (see charset=) then
    # the character set information will also be included in the content type
    # information.
    def content_type=(mime_type)
      self.headers["Content-Type"] =
        if mime_type =~ /charset/ || (c = charset).nil?
          mime_type.to_s
        else
          "#{mime_type}; charset=#{c}"
        end
    end

    # Returns the response's content MIME type, or nil if content type has been set.
    def content_type
      content_type = String(headers["Content-Type"] || headers["type"]).split(";")[0]
      content_type.blank? ? nil : content_type
    end

    # Set the charset of the Content-Type header. Set to nil to remove it.
    # If no content type is set, it defaults to HTML.
    def charset=(charset)
      headers["Content-Type"] =
        if charset
          "#{content_type || Mime::HTML}; charset=#{charset}"
        else
          content_type || Mime::HTML.to_s
        end
    end

    def charset
      charset = String(headers["Content-Type"] || headers["type"]).split(";")[1]
      charset.blank? ? nil : charset.strip.split("=")[1]
    end

    def last_modified
      if last = headers['Last-Modified']
        Time.httpdate(last)
      end
    end

    def last_modified?
      headers.include?('Last-Modified')
    end

    def last_modified=(utc_time)
      headers['Last-Modified'] = utc_time.httpdate
    end

    def etag
      headers['ETag']
    end

    def etag?
      headers.include?('ETag')
    end

    def etag=(etag)
      headers['ETag'] = %("#{Digest::MD5.hexdigest(ActiveSupport::Cache.expand_cache_key(etag))}")
    end

    def redirect(url, status)
      self.status = status
      self.location = url.gsub(/[\r\n]/, '')
      self.body = "<html><body>You are being <a href=\"#{CGI.escapeHTML(url)}\">redirected</a>.</body></html>"
    end

    def sending_file?
      headers["Content-Transfer-Encoding"] == "binary"
    end

    def assign_default_content_type_and_charset!
      self.content_type ||= Mime::HTML
      self.charset ||= default_charset unless sending_file?
    end

    def prepare!
      assign_default_content_type_and_charset!
      handle_conditional_get!
      set_content_length!
      convert_content_type!
      convert_language!
      convert_cookies!
    end

    def each(&callback)
      if @body.respond_to?(:call)
        @writer = lambda { |x| callback.call(x) }
        @body.call(self, self)
      elsif @body.respond_to?(:to_str)
        yield @body
      else
        @body.each(&callback)
      end

      @writer = callback
      @block.call(self) if @block
    end

    def write(str)
      @writer.call str.to_s
      str
    end

    def flush #:nodoc:
      ActiveSupport::Deprecation.warn(
        'Calling output.flush is no longer needed for streaming output ' +
        'because ActionController::Response automatically handles it', caller)
    end

    def set_cookie(key, value)
      if value.has_key?(:http_only)
        ActiveSupport::Deprecation.warn(
          "The :http_only option in ActionController::Response#set_cookie " +
          "has been renamed. Please use :httponly instead.", caller)
        value[:httponly] ||= value.delete(:http_only)
      end

      super(key, value)
    end

    private
      def handle_conditional_get!
        if etag? || last_modified?
          set_conditional_cache_control!
        elsif nonempty_ok_response?
          self.etag = body

          if request && request.etag_matches?(etag)
            self.status = '304 Not Modified'
            self.body = ''
          end

          set_conditional_cache_control!
        end
      end

      def nonempty_ok_response?
        ok = !status || status.to_s[0..2] == '200'
        ok && body.is_a?(String) && !body.blank?
      end

      def set_conditional_cache_control!
        if headers['Cache-Control'] == DEFAULT_HEADERS['Cache-Control']
          headers['Cache-Control'] = 'private, max-age=0, must-revalidate'
        end
      end

      def convert_content_type!
        headers['Content-Type'] ||= "text/html"
        headers['Content-Type'] += "; charset=" + headers.delete('charset') if headers['charset']
      end

      # Don't set the Content-Length for block-based bodies as that would mean
      # reading it all into memory. Not nice for, say, a 2GB streaming file.
      def set_content_length!
        if status && status.to_s[0..2] == '204'
          headers.delete('Content-Length')
        elsif length = headers['Content-Length']
          headers['Content-Length'] = length.to_s
        elsif !body.respond_to?(:call) && (!status || status.to_s[0..2] != '304')
          headers["Content-Length"] = (body.respond_to?(:bytesize) ? body.bytesize : body.size).to_s
        end
      end

      def convert_language!
        headers["Content-Language"] = headers.delete("language") if headers["language"]
      end

      def convert_cookies!
        cookies = Array(headers['Set-Cookie']).compact
        headers['Set-Cookie'] = cookies unless cookies.empty?
      end
  end
end