#-- vim:sw=2:et
#++
#
# :title: Translator plugin for rbot
#
# Author:: Yaohan Chen <yaohan.chen@gmail.com>
# Copyright:: (C) 2007 Yaohan Chen
# License:: GPLv2
#
# This plugin allows using rbot to translate text on a few translation services
#
# TODO
#
# * Configuration for whether to show translation engine
# * Optionally sync default translators with karma.rb ranking

require 'set'
require 'timeout'

# base class for implementing a translation service
# = Attributes
# direction:: supported translation directions, a hash where each key is a source
#             language name, and each value is Set of target language names. The
#             methods in the Direction module are convenient for initializing this
#             attribute
class Translator
  INFO = 'Some translation service'

  class UnsupportedDirectionError < ArgumentError
  end

  class NoTranslationError < RuntimeError
  end

  attr_reader :directions, :cache

  def initialize(directions, cache={}, bot)
    @directions = directions
    @cache = cache
    @bot = bot
  end

  # whether the translator supports this direction
  def support?(from, to)
    from != to && @directions[from].include?(to)
  end

  # this implements argument checking and caching. subclasses should define the
  # do_translate method to implement actual translation
  def translate(text, from, to)
    raise UnsupportedDirectionError unless support?(from, to)
    raise ArgumentError, _("Cannot translate empty string") if text.empty?
    request = [text, from, to]
    unless @cache.has_key? request
      translation = do_translate(text, from, to)
      raise NoTranslationError if translation.empty?
      @cache[request] = translation
    else
      @cache[request]
    end
  end

  module Direction
    # given the set of supported languages, return a hash suitable for the directions
    # attribute which includes any language to any other language
    def self.all_to_all(languages)
      directions = all_to_none(languages)
      languages.each {|l| directions[l] = languages.to_set}
      directions
    end

    # a hash suitable for the directions attribute which includes any language from/to
    # the given set of languages (center_languages)
    def self.all_from_to(languages, center_languages)
      directions = all_to_none(languages)
      center_languages.each {|l| directions[l] = languages - [l]}
      (languages - center_languages).each {|l| directions[l] = center_languages.to_set}
      directions
    end

    # get a hash from a list of pairs
    def self.pairs(list_of_pairs)
      languages = list_of_pairs.flatten.to_set
      directions = all_to_none(languages)
      list_of_pairs.each do |(from, to)|
        directions[from] << to
      end
      directions
    end

    # an empty hash with empty sets as default values
    def self.all_to_none(languages)
      Hash.new do |h, k|
        # always return empty set when the key is non-existent, but put empty set in the
        # hash only if the key is one of the languages
        if languages.include? k
          h[k] = Set.new
        else
          Set.new
        end
      end
    end
  end
end

class YandexTranslator < Translator
  INFO = 'Yandex Translator <http://translate.yandex.com/>'
  LANGUAGES = %w{ar az be bg ca cs da de el en es et fi fr he hr hu hy it ka lt lv mk nl no pl pt ro ru sk sl sq sr sv tr uk}

  URL = 'https://translate.yandex.net/api/v1.5/tr.json/translate?key=%s&lang=%s-%s&text=%s'
  KEY = 'trnsl.1.1.20140326T031210Z.1e298c8adb4058ed.d93278fea8d79e0a0ba76b6ab4bfbf6ac43ada72'
  def initialize(cache, bot)
    require 'uri'
    require 'json'
    super(Translator::Direction.all_to_all(LANGUAGES), cache, bot)
  end

  def translate(text, from, to)
    res = @bot.httputil.get_response(URL % [KEY, from, to, URI.escape(text)])
    res = JSON.parse(res.body)

    if res['code'] != 200
      raise Translator::NoTranslationError
    else
      res['text'].join(' ')
    end
  end

end

class TranslatorPlugin < Plugin
  Config.register Config::IntegerValue.new('translator.timeout',
    :default => 30, :validate => Proc.new{|v| v > 0},
    :desc => _("Number of seconds to wait for the translation service before timeout"))
  Config.register Config::StringValue.new('translator.destination',
    :default => "en",
    :desc => _("Default destination language to be used with translate command"))

  TRANSLATORS = {
    'yandex' => YandexTranslator,
  }

  def initialize
    super
    @failed_translators = []
    @translators = {}
    TRANSLATORS.each_pair do |name, c|
      watch_for_fail(name) do
        @translators[name] = c.new(@registry.sub_registry(name), @bot)
        map "#{name} :from :to *phrase",
          :action => :cmd_translate, :thread => true
      end
    end

    Config.register Config::ArrayValue.new('translator.default_list',
      :default => TRANSLATORS.keys,
      :validate => Proc.new {|l| l.all? {|t| TRANSLATORS.has_key?(t)}},
      :desc => _("List of translators to try in order when translator name not specified"),
      :on_change => Proc.new {|bot, v| update_default})
    update_default
  end

  def watch_for_fail(name, &block)
    begin
      yield
    rescue Exception
      debug 'Translator error: '+$!.to_s
      debug $@.join("\n")
      @failed_translators << { :name => name, :reason => $!.to_s }

      warning _("Translator %{name} cannot be used: %{reason}") %
             {:name => name, :reason => $!}
      map "#{name} [*args]", :action => :failed_translator,
                             :defaults => {:name => name, :reason => $!}
    end
  end

  def failed_translator(m, params)
    m.reply _("Translator %{name} cannot be used: %{reason}") %
            {:name => params[:name], :reason => params[:reason]}
  end

  def help(plugin, topic=nil)
    case (topic.intern rescue nil)
    when :failed
      unless @failed_translators.empty?
        failed_list = @failed_translators.map { |t| _("%{bold}%{translator}%{bold}: %{reason}") % {
          :translator => t[:name],
          :reason => t[:reason],
          :bold => Bold
        }}

        _("Failed translators: %{list}") % { :list => failed_list.join(", ") }
      else
        _("None of the translators failed")
      end
    else
      if @translators.has_key?(plugin)
        translator = @translators[plugin]
        _('%{translator} <from> <to> <phrase> => Look up phrase using %{info}, supported from -> to languages: %{directions}') % {
          :translator => plugin,
          :info => translator.class::INFO,
          :directions => translator.directions.map do |source, targets|
                           _('%{source} -> %{targets}') %
                           {:source => source, :targets => targets.to_a.join(', ')}
                         end.join(' | ')
        }
      else
        help_str = _('Command: <translator> <from> <to> <phrase>, where <translator> is one of: %{translators}. If "translator" is used in place of the translator name, the first translator in translator.default_list which supports the specified direction will be picked automatically. Use "help <translator>" to look up supported from and to languages') %
                     {:translators => @translators.keys.join(', ')}

        help_str << "\n" + _("%{bold}Note%{bold}: %{failed_amt} translators failed, see %{reverse}%{prefix}help translate failed%{reverse} for details") % {
          :failed_amt => @failed_translators.size,
          :bold => Bold,
          :reverse => Reverse,
          :prefix => @bot.config['core.address_prefix'].first
        }

        help_str
      end
    end
  end

  def languages
    @languages ||= @translators.map { |t| t.last.directions.keys }.flatten.uniq
  end

  def update_default
    @default_translators = bot.config['translator.default_list'] & @translators.keys
  end

  def cmd_translator(m, params)
    params[:to] = @bot.config['translator.destination'] if params[:to].nil?
    params[:from] ||= 'auto'
    translator = @default_translators.find {|t| @translators[t].support?(params[:from], params[:to])}

    if translator
      cmd_translate m, params.merge({:translator => translator, :show_provider => false})
    else
      m.reply _('None of the default translators (translator.default_list) supports translating from %{source} to %{target}') % {:source => params[:from], :target => params[:to]}
    end
  end

  def cmd_translate(m, params)
    # get the first word of the command
    tname = params[:translator] || m.message[/\A(\w+)\s/, 1]
    translator = @translators[tname]
    from, to, phrase = params[:from], params[:to], params[:phrase].to_s
    if translator
      watch_for_fail(tname) do
        begin
          translation = Timeout.timeout(@bot.config['translator.timeout']) do
            translator.translate(phrase, from, to)
          end
          m.reply(if params[:show_provider]
                    _('%{translation} (provided by %{translator})') %
                      {:translation => translation, :translator => tname.gsub("_", " ")}
                  else
                    translation
                  end)

        rescue Translator::UnsupportedDirectionError
          m.reply _("%{translator} doesn't support translating from %{source} to %{target}") %
                  {:translator => tname, :source => from, :target => to}
        rescue Translator::NoTranslationError
          m.reply _('%{translator} failed to provide a translation') %
                  {:translator => tname}
        rescue Timeout::Error
          m.reply _('The translator timed out')
        end
      end
    else
      m.reply _('No translator called %{name}') % {:name => tname}
    end
  end

  # URL translation has nothing to do with Translators so let's make it
  # separate, and Google exclusive for now
  def cmd_translate_url(m, params)
    params[:to] = @bot.config['translator.destination'] if params[:to].nil?
    params[:from] ||= 'auto'

    translate_url = "http://translate.google.com/translate?sl=%{from}&tl=%{to}&u=%{url}" % {
      :from => params[:from],
      :to   => params[:to],
      :url  => CGI.escape(params[:url].to_s)
    }

    m.reply(translate_url)
  end
end

plugin = TranslatorPlugin.new
req = Hash[*%w(from to).map { |e| [e.to_sym, /#{plugin.languages.join("|")}/] }.flatten]

plugin.map 'translate [:from] [:to] :url',
           :action => :cmd_translate_url, :requirements => req.merge(:url => %r{^https?://[^\s]*})
plugin.map 'translator [:from] [:to] :url',
           :action => :cmd_translate_url, :requirements => req.merge(:url => %r{^https?://[^\s]*})
plugin.map 'translate [:from] [:to] *phrase',
           :action => :cmd_translator, :thread => true, :requirements => req
plugin.map 'translator [:from] [:to] *phrase',
           :action => :cmd_translator, :thread => true, :requirements => req