module Agents
  class TranslationAgent < Agent

    cannot_be_scheduled!

    description <<-MD
      You can use Translation Agent to translate text between natural languages.
      Services are provided using Microsoft Translator. You can [sign up](https://datamarket.azure.com/dataset/bing/microsofttranslator) and [register your application](https://datamarket.azure.com/developer/applications/register) to get `client_id` and `client_secret` which are required to use this agent.
      `to` must be filled with a [translator language code](http://msdn.microsoft.com/en-us/library/hh456380.aspx).

      Specify what you would like to translate in `content` field, by specifying key and JSONPath of content to be translated.

      `expected_receive_period_in_days` is the maximum number of days you would allow to pass between events.
    MD

    event_description "User defined"

    def default_options
      {
        :client_id => "xxxxxx",
        :client_secret => "xxxxxx",
        :to => "fi",
        :expected_receive_period_in_days => 1,
        :content => {
          :text => "$.message.text",
          :content => "$.xyz"
        }
      }
    end

    def working?
      last_receive_at && last_receive_at > options[:expected_receive_period_in_days].to_i.days.ago && !recent_error_logs?
    end

    def translate(text, to, access_token)
      translate_uri = URI 'http://api.microsofttranslator.com/v2/Ajax.svc/Translate'
      params = {
          :text => text,
          :to => to
      }
      translate_uri.query = URI.encode_www_form params
      request = Net::HTTP::Get.new translate_uri.request_uri
      request['Authorization'] = "Bearer" + " " + access_token
      http = Net::HTTP.new translate_uri.hostname, translate_uri.port
      response = http.request request
      YAML.load response.body
    end

    def validate_options
      unless options[:client_id].present? && options[:client_secret].present? && options[:to].present? && options[:content].present? && options[:expected_receive_period_in_days].present?
        errors.add :base, "client_id,client_secret,to,expected_receive_period_in_days and content are all required"
      end
    end

    def postform(uri, params)
      req = Net::HTTP::Post.new(uri.request_uri)
      req.form_data = params
      Net::HTTP.start(uri.hostname, uri.port, :use_ssl => true) { |http| http.request(req) }
    end

    def receive(incoming_events)
      auth_uri = URI "https://datamarket.accesscontrol.windows.net/v2/OAuth2-13"
      response = postform auth_uri, :client_id => options[:client_id],
                                    :client_secret => options[:client_secret],
                                    :scope => "http://api.microsofttranslator.com",
                                    :grant_type => "client_credentials"
      access_token = JSON.parse(response.body)["access_token"]
      incoming_events.each do |event|
        translated_event = {}
        options[:content].each_pair do |key, value|
          to_be_translated = Utils.values_at event.payload, value
          translated_event[key] = translate to_be_translated.first, options[:to], access_token
        end
        create_event :payload => translated_event
      end
    end
  end
end