require 'faraday'
require 'json'

module Lingo24

  # +PremiumMTAPI+ is an API wrapper for the Lingo24 Premium Machine Translation API
  # (https://developer.lingo24.com/premium-machine-translation-api).
  #
  # Machine Translation (MT) is a cost-effective, quick translation option for large volumes of content, or cases where
  # it is not feasible to use a professional human translator.
  #
  # The Lingo24 Premium Machine Translation API provides direct, secure, high volume access to our Premium Machine
  # Translation Engines. Encrypted using SSL and with no data storage at Lingo24, you can translate safely with no data
  # privacy concerns.
  #
  # We have developed a range of Premium MT engines focusing on specific language combinations and subject areas,
  # including Law, Information Technology, Pharmaceuticals, Business, IT and many more. This focused approach results in
  # much higher-quality output than generic engines from big-name translators, with the API selecting the best suited
  # engine based on the content of the text for translation.                                                                                                                                                                                                                                  Ideal for those scenarios where no post-editing is required, such as gisting (getting a basic understanding of a source text), real-time translation (tweets, IM chat, etc) or sentiment analysis, the Premium MT API enables easy access to raw machine translation.
  #
  class PremiumMTAPI
    BASE_API_URL = "https://api.lingo24.com/mt/v1/"

    public
    # Creates a new API client to handle calls to the Lingo24 Premium Machine Translation API.
    #
    # Parameters:
    # <tt>user_key</tt> - a string containing the user_key issued by the Lingo24 developer portal for your application.
    def initialize(user_key)
      @user_key = user_key
    end

    # Synchronous call to translate text using the Lingo24 Premium Machine Translation API. When calling this method
    # the text sent is analysed and routed to the engine most likely to produce the highest quality output.
    #
    # NOTE: Customers who have custom engines for specific business domains will have these prioritised ahead of Lingo24
    # vertical engines.
    #
    # Options:
    # <tt>text</tt> - a string for translation
    # <tt>source</tt> - a string containing the ISO-639-1 code for the source language
    # <tt>target</tt> - a string containing the ISO-639-1 code for the target language
    def translate(text, source, target)
      params = {:q => text, :source => source, :target => target, :user_key => @user_key}
      handle_request('translate', params, 'translation')
    end

    # Synchronous call to translate text using the Lingo24 Premium Machine Translation API. When calling this method
    # the text sent is analysed and routed to the engine most likely to produce the highest quality output.
    #
    # NOTE: Customers who have custom engines for specific business domains will have these prioritised ahead of Lingo24
    # vertical engines.
    #
    # Options:
    # <tt>text</tt> - a string for translation
    # <tt>source</tt> - a +Lingo24::Language+ containing the source language
    # <tt>target</tt> - a +Lingo24::Language+ containing the target language
    def translate_language(text, source, target)
      params = {:q => text, :source => source.code, :target => target.code, :user_key => @user_key}
      handle_request('translate', params, 'translation')
    end

    # Synchronous call to translate text using a specific Lingo24 Premium Machine Translation engine. This method is
    # typically used by customers who have a custom engine and want to ignore the automatic classification..
    #
    # Options:
    # <tt>text</tt> - a string for translation
    # <tt>source</tt> - a +Lingo24::Language+ containing the source language
    # <tt>target</tt> - a +Lingo24::Language+ containing the target language
    def translate_specific(text, id)
      params = {:q => text, :id => id, :user_key => @user_key}
      handle_request('translate', params, 'translation')
    end

    ##
    # Returns a list of the supported source languages for +PremiumMTAPI+. This method will return a list containing
    # +Lingo24::Language+ objects which provide access to both the ISO-639-1 code as well as a friendly name.
    #
    # If the +target+ is nil, the list will contain all possible source languages.
    # If the +target+ is set, the list will contain only the source languages that
    # can generate the target language.
    def get_source_langs(target = nil)
      if (target.nil?)
        params = { :user_key => @user_key }
      else
        params = { :user_key => @user_key, :target => target }
      end
      source_langs = handle_request('sourcelangs', params, 'source_langs')
      source_langs.map { |code, name| Lingo24::Language.new(code, name) }
    end

    ##
    # Returns a list of the supported target languages for +PremiumMTAPI+. This method will return a list containing
    # +Lingo24::Language+ objects which provide access to both the ISO-639-1 code as well as a friendly name.
    #
    # If +source+ is nil, the list will contain all possible target languages.
    # If +source+ is set, the list will contain only the target languages that
    # can generate the source language.
    def get_target_langs(source = nil)
      if (source.nil?)
        params = { :user_key => @user_key }
      else
        params = { :user_key => @user_key, :source => source }
      end
      target_langs = handle_request('targetlangs', params, 'target_langs')
      target_langs.map { |code, name| Lingo24::Language.new(code, name) }
    end

    private
    # Private method to handle the interaction between the client library and the Lingo24 API.
    def handle_request(method, params, field)
      response = Faraday.post BASE_API_URL + method, params do |request|
        request.options[:timeout] = 300
        request.options[:open_timeout] = 120
      end
      if (response.status.equal? '200')
        raise Lingo24::Exception.new(response.status, response.body)
      elsif (JSON.parse(response.body)['errors'])
        raise Lingo24::Exception.new('500', JSON.parse(response.body)['errors'][0])
      else
        JSON.parse(response.body)[field]
      end
    end

  end

end