require 'dispatcher'
require 'stringio'
require 'uri'

module ActionController
  module Integration

    # An integration Session instance represents a set of requests and responses
    # performed sequentially by some virtual user. Becase you can instantiate
    # multiple sessions and run them side-by-side, you can also mimic (to some
    # limited extent) multiple simultaneous users interacting with your system.
    #
    # Typically, you will instantiate a new session using IntegrationTest#open_session,
    # rather than instantiating Integration::Session directly.
    class Session
      include Test::Unit::Assertions
      include ActionController::TestProcess
      include ActionController::Routing::NamedRoutes

      # The integer HTTP status code of the last request.
      attr_reader :status

      # The status message that accompanied the status code of the last request.
      attr_reader :status_message

      # The URI of the last request.
      attr_reader :path

      # The hostname used in the last request.
      attr_reader :host

      # A map of the cookies returned by the last response, and which will be
      # sent with the next request.
      attr_reader :cookies

      # A map of the headers returned by the last response.
      attr_reader :headers

      # A reference to the controller instance used by the last request.
      attr_reader :controller

      # A reference to the request instance used by the last request.
      attr_reader :request

      # A reference to the response instance used by the last request.
      attr_reader :response

      # Create an initialize a new Session instance.
      def initialize
        reset!
      end

      # Resets the instance. This can be used to reset the state information
      # in an existing session instance, so it can be used from a clean-slate
      # condition.
      #
      #   session.reset!
      def reset!
        @status = @path = @host = @headers = nil
        @result = @status_message = nil
        @https = false
        @cookies = {}
        @controller = @request = @response = nil
      
        initialize_url_writer
      end

      # Specify whether or not the session should mimic a secure HTTPS request.
      #
      #   session.https!
      #   session.https!(false)
      def https!(flag=true)
        @https = flag
        initialize_url_writer
      end

      # Return +true+ if the session is mimicing a secure HTTPS request.
      #
      #   if session.https?
      #     ...
      #   end
      def https?
        @https
      end

      # Set the host name to use in the next request.
      #
      #   session.host! "www.example.test"
      def host!(name)
        @host = name
        initialize_url_writer
      end

      # Follow a single redirect response. If the last response was not a
      # redirect, an exception will be raised. Otherwise, the redirect is
      # performed on the location header.
      def follow_redirect!
        raise "not a redirect! #{@status} #{@status_message}" unless redirect?
        get(interpret_uri(headers["location"].first))
      end

      # Performs a GET request, following any subsequent redirect. Note that
      # the redirects are followed until the response is not a redirect--this
      # means you may run into an infinite loop if your redirect loops back to
      # itself.
      def get_via_redirect(path, args={})
        get path, args
        follow_redirect! while redirect?
      end

      # Performs a POST request, following any subsequent redirect. This is
      # vulnerable to infinite loops, the same as #get_via_redirect.
      def post_via_redirect(path, args={})
        post path, args
        follow_redirect! while redirect?
      end

      # Returns +true+ if the last response was a redirect.
      def redirect?
        status/100 == 3
      end

      # Performs a GET request with the given parameters. The parameters may
      # be +nil+, a Hash, or a string that is appropriately encoded
      # (application/x-www-form-urlencoded or multipart/form-data).
      def get(path, parameters=nil, headers=nil)
        process :get, path, parameters, headers
      end

      # Performs a POST request with the given parameters. The parameters may
      # be +nil+, a Hash, or a string that is appropriately encoded
      # (application/x-www-form-urlencoded or multipart/form-data).
      def post(path, parameters=nil, headers=nil)
        process :post, path, parameters, headers
      end

      # Performs an XMLHttpRequest request with the given parameters, mimicing
      # the request environment created by the Prototype library. The parameters
      # may be +nil+, a Hash, or a string that is appropriately encoded
      # (application/x-www-form-urlencoded or multipart/form-data).
      def xml_http_request(path, parameters=nil, headers=nil)
        headers = (headers || {}).merge("X-Requested-With" => "XMLHttpRequest")
        post(path, parameters, headers)
      end

      # Returns the URL for the given options, according to the rules specified
      # in the application's routes.
      def url_for(options)
        @rewriter.rewrite(options)
      end

      private
  
        class MockCGI < CGI #:nodoc:
          attr_accessor :stdinput, :stdoutput, :env_table

          def initialize(env, input=nil)
            self.env_table = env
            self.stdinput = StringIO.new(input || "")
            self.stdoutput = StringIO.new

            super()
          end
        end

        # Tailors the session based on the given URI, setting the HTTPS value
        # and the hostname.
        def interpret_uri(path)
          location = URI.parse(path)
          https! URI::HTTPS === location
          host! location.host
          location.query ? "#{location.path}?#{location.query}" : location.path
        end

        # Performs the actual request.
        def process(method, path, parameters=nil, headers=nil)
          data = requestify(parameters)
          path = interpret_uri(path) if path =~ %r{://}
          path = "/#{path}" unless path[0] == ?/
          @path = path
          env = {}

          if method == :get
            env["QUERY_STRING"] = data
            data = nil
          end

          env.update(
            "REQUEST_METHOD" => method.to_s.upcase,
            "REQUEST_URI"    => path,
            "HTTP_HOST"      => host,
            "SERVER_PORT"    => (https? ? "443" : "80"),
            "CONTENT_TYPE"   => "application/x-www-form-urlencoded",
            "CONTENT_LENGTH" => data ? data.length.to_s : nil,
            "HTTP_COOKIE"    => encode_cookies,
            "HTTPS"          => https? ? "on" : "off"
          )

          (headers || {}).each do |key, value|
            key = key.to_s.upcase.gsub(/-/, "_")
            key = "HTTP_#{key}" unless env.has_key?(key)
            env[key] = value
          end

          unless ActionController::Base.respond_to?(:clear_last_instantiation!)
            ActionController::Base.send(:include, ControllerCapture)
          end

          ActionController::Base.clear_last_instantiation!

          cgi = MockCGI.new(env, data)
          Dispatcher.dispatch(cgi, ActionController::CgiRequest::DEFAULT_SESSION_OPTIONS, cgi.stdoutput)
          @result = cgi.stdoutput.string

          @controller = ActionController::Base.last_instantiation
          @request = @controller.request
          @response = @controller.response

          parse_result
        end

        # Parses the result of the response and extracts the various values,
        # like cookies, status, headers, etc.
        def parse_result
          headers, result_body = @result.split(/\r\n\r\n/, 2)

          @headers = Hash.new { |h,k| h[k] = [] }
          headers.each_line do |line|
            key, value = line.strip.split(/:\s*/, 2)
            @headers[key.downcase] << value
          end

          (@headers['set-cookie'] || [] ).each do |string|
            name, value = string.match(/^(.*?)=(.*?);/)[1,2]
            @cookies[name] = value
          end

          @status, @status_message = @headers["status"].first.split(/ /)
          @status = @status.to_i
        end

        # Encode the cookies hash in a format suitable for passing to a 
        # request.
        def encode_cookies
          cookies.inject("") do |string, (name, value)|
            string << "#{name}=#{value}; "
          end
        end

        # Initialize the URL writer object that will be used to generate
        # URL's.
        def initialize_url_writer
          cgi = MockCGI.new('REQUEST_METHOD' => "GET",
                            'QUERY_STRING'   => "",
                            "REQUEST_URI"    => "/",
                            "HTTP_HOST"      => host,
                            "SERVER_PORT"    => https? ? "80" : "443",
                            "HTTPS"          => https? ? "on" : "off")                          
          @rewriter = ActionController::UrlRewriter.new(ActionController::CgiRequest.new(cgi), {})
        end

        # Convert the given parameters to a request string. The parameters may
        # be a string, +nil+, or a Hash.
        def requestify(parameters)
          if Hash === parameters
            parameters.empty? ? nil :
              parameters.map { |k,v| "#{CGI.escape(k.to_s)}=#{CGI.escape(v.to_s)}" }.join("&")
          else
            parameters
          end
        end

    end

    # A module used to extend ActionController::Base, so that integration tests
    # can capture the controller used to satisfy a request.
    module ControllerCapture #:nodoc:
      def self.included(base)
        base.extend(ClassMethods)
        base.class_eval do
          class <<self
            alias_method :new_without_capture, :new
            alias_method :new, :new_with_capture
          end
        end
      end

      module ClassMethods
        mattr_accessor :last_instantiation

        def clear_last_instantiation!
          self.last_instantiation = nil
        end
    
        def new_with_capture(*args)
          self.last_instantiation ||= new_without_capture(*args)
        end
      end
    end
  end

  # An IntegrationTest is one that spans multiple controllers and actions,
  # tying them all together to ensure they work together as expected. It tests
  # more completely than either unit or functional tests do, exercising the
  # entire stack, from the dispatcher to the database.
  #
  # At its simplest, you simply extend IntegrationTest and write your tests
  # using the get/post methods:
  #
  #   require "#{File.dirname(__FILE__)}/test_helper"
  #   require "integration_test"
  #
  #   class ExampleTest < ActionController::IntegrationTest
  #     fixtures :people
  #
  #     def test_login
  #       # get the login page
  #       get "/login"
  #       assert_equal 200, status
  #
  #       # post the login and follow through to the home page
  #       post "/login", :username => people(:jamis).username,
  #         :password => people(:jamis).password
  #       follow_redirect!
  #       assert_equal 200, status
  #       assert_equal "/home", path
  #     end
  #   end
  #
  # However, you can also have multiple session instances open per test, and
  # even extend those instances with assertions and methods to create a very
  # powerful testing DSL that is specific for your application. You can even
  # reference any named routes you happen to have defined!
  #
  #   require "#{File.dirname(__FILE__)}/test_helper"
  #   require "integration_test"
  #
  #   class AdvancedTest < ActionController::IntegrationTest
  #     fixtures :people, :rooms
  #
  #     def test_login_and_speak
  #       jamis, david = login(:jamis), login(:david)
  #       room = rooms(:office)
  #
  #       jamis.enter(room)
  #       jamis.speak(room, "anybody home?")
  #
  #       david.enter(room)
  #       david.speak(room, "hello!")
  #     end
  #
  #     private
  #
  #       module CustomAssertions
  #         def enter(room)
  #           # reference a named route, for maximum internal consistency!
  #           get(room_url(:id => room.id))
  #           assert(...)
  #           ...
  #         end
  #
  #         def speak(room, message)
  #           xml_http_request "/say/#{room.id}", :message => message
  #           assert(...)
  #           ...
  #         end
  #       end
  #
  #       def login(who)
  #         open_session do |sess|
  #           sess.extend(CustomAssertions)
  #           who = people(who)
  #           sess.post "/login", :username => who.username,
  #             :password => who.password
  #           assert(...)
  #         end
  #       end
  #   end
  class IntegrationTest < Test::Unit::TestCase
    # Work around test/unit's requirement that every subclass of TestCase have
    # at least one test method. Note that this implementation extends to all
    # subclasses, as well, so subclasses of IntegrationTest may also exist
    # without any test methods.
    def run(*args) #:nodoc:
      return if @method_name == :default_test
      super   
    end

    # Reset the current session. This is useful for testing multiple sessions
    # in a single test case.
    def reset!
      @integration_session = open_session
    end

    %w(get post cookies assigns).each do |method|
      define_method(method) do |*args|
        @integration_session.send(method, *args)
      end
    end

    # Open a new session instance. If a block is given, the new session is
    # yielded to the block before being returned.
    #
    #   session = open_session do |sess|
    #     sess.extend(CustomAssertions)
    #   end
    #
    # By default, a single session is automatically created for you, but you
    # can use this method to open multiple sessions that ought to be tested
    # simultaneously.
    def open_session
      session = Integration::Session.new
      yield session if block_given?
      session
    end

    # Delegate unhandled messages to the current session instance.
    def method_missing(sym, *args, &block)
      reset! unless @integration_session
      @integration_session.send(sym, *args, &block)
    end
  end
end