require "rack"
require "rack/openid"

module Rack
  class GoogleMarketplace
    attr_accessor :domain_param, :session_key

    def initialize app, &block
      @app = app

      # Set default values
      @domain_param ||= "domain"
      @session_key  ||= "user_id"
      @return_to    ||= "/"

      yield self if block_given?
    end

    # Duplicate self on call to make code thread safe
    def call env
      dup._call env
    end

    def _call env
      status, headers, response = @app.call env
      request = Rack::Request.new env
      session = env["rack.session"]
      @domain = request[domain_param]

      if env["PATH_INFO"] == "/login" and @domain
        status = 401
        headers["WWW-Authenticate"] = Rack::OpenID.build_header(
          :identifier => identifier,
          :return_to  => "/?#{query({@domain_param => @domain})}",
          :required   => ax_required,
          :method     => "post"
        )
      elsif resp = env["rack.openid.response"] and @domain
        if resp.status == :success
          user = {}
          user[:email]      = ax_response ax_schema("contact/email")
          user[:first_name] = ax_response ax_schema("namePerson/first")
          user[:last_name]  = ax_response ax_schema("namePerson/last")

          env["rack.googlemarketplace.openid_response"] = resp
          env["rack.googlemarketplace.user"] = user
          env["rack.googlemarketplace.domain"] = @domain
        end
        status = 302
        headers["Location"] = @return_to
      end

      [ status, headers, response ]
    end

    def identifier
      "https://www.google.com/accounts/o8/site-xrds?hd=#{@domain}"
    end

    def ax_required
      [ ax_schema("contact/email"),
        ax_schema("namePerson/first"),
        ax_schema("namePerson/last") ]
    end

    def ax_response resp
      OpenID::AX::FetchResponse.from_success_response(resp)
    end

    private
    def ax_schema path
      "http://axschema.org/#{path}"
    end

    def query(params = {})
      Rack::Utils.build_query params
    end
  end
end