# google_translate.rb

require 'open-uri'

require 'cgi'
require 'json'

class GoogleTranslate
  GOOGLE_TRANSLATE_SERVICE_URL = "http://translate.google.com"

  def self.Exception(*names)
    cl = Module === self ? self : Object

    names.each { |n| cl.const_set(n, Class.new(Exception)) }
  end

  Exception :MissingFromLanguage, :MissingToLanguage, :MissingTextLanguage, :TranslateServerIsDown,
            :InvalidResponse, :MissingText, :MissingTestText

  def translate(from, to, from_text, options={})
    raise(MissingFromLanguage) if from.nil?
    raise(MissingToLanguage) if to.nil?
    raise(MissingTextLanguage) if from_text.nil?

    begin
      url = GOOGLE_TRANSLATE_SERVICE_URL + "/translate_a/t?client=t&text=#{from_text}&hl=#{from}&sl=#{from}&tl=#{to}&multires=1&prev=btn&ssel=0&tsel=4&uptl=#{to}&alttl=#{from}&sc=1"

      open(URI.escape(url)) do |stream|
        content = stream.read

        s = content.split(',').collect { |s| s == '' ? "\"\"" : s }.join(",")

        result = JSON.parse(s)

        raise(TranslateServerIsDown) if (!result || result.empty?)

        #        raise(InvalidResponse, result["responseDetails"]) if response.code.to_i != 200 # success

        r1 = result[0][0][0]
        r2 = result[0][0][2]

        [r1, r2]
      end
    rescue Exception => e
      raise(TranslateServerIsDown)
    end
  end

  def supported_languages
    fetch_languages(GOOGLE_TRANSLATE_SERVICE_URL, [])
  end

  private

  def fetch_languages(request, keys)
    response = {}
    open(URI.escape(request)) do |stream|
      content = stream.read

      from_languages = collect_languages content, 0, 'sl', 'gt-sl'
      to_languages   = collect_languages content, 1, 'tl', 'gt-tl'

      response[:from_languages] = from_languages
      response[:to_languages]   = to_languages
    end

    response
  end

  def collect_languages buffer, index, tag_name, tag_id
    languages = []

    spaces = '\s?'
    quote  = '(\s|\'|")?'

    id_part       = "id#{spaces}=#{spaces}#{quote}#{tag_id}#{quote}"
    name_part     = "name#{spaces}=#{spaces}#{quote}#{tag_name}#{quote}"
    class_part    = "class#{spaces}=#{spaces}#{quote}(.*)?#{quote}"
    tabindex_part = "tabindex#{spaces}=#{spaces}#{quote}0#{quote}"
    phrase        = "#{spaces}#{id_part}#{spaces}#{name_part}#{spaces}#{class_part}#{spaces}#{tabindex_part}#{spaces}"

    re1 = buffer.split(%r{<select#{phrase}>(.*)?</select>}).select { |x| x =~ %r{<option} }

    stopper = "</select>"

    text = re1[index]

    if index == 0
      pos  = text.index(stopper)
      text = text[0..pos]
    end

    re2     = /<option(\s*)value="([a-z|A-Z|-]*)">([a-z|A-Z|\(|\)|\s]*)<\/option>/
    matches = text.gsub(/selected/i, '').squeeze.scan(re2)

    if matches.size == 0
      re2     = /<option(\s*)value=([a-z|A-Z|-]*)>([a-z|A-Z|\(|\)|\s]*)<\/option>/
      matches = text.gsub(/selected/i, '').squeeze.scan(re2)
    end

    matches.each do |m| languages << Language.new(m[2], m[1])
    end

    languages
  end
end