Simple wrapper with caching for Amazon Translate

amazon_translate.rb

# Simple wrapper around the amazon translate SDK that also tries to
# implement basic caching to avoid sending (and being charged for)
# duplicate translations.
#
# Supports JA, EN at the moment only.
#
require 'digest/sha2'
module AmazonTranslate
  class <<self

    def to_ja(string)
      cached_ja_tanslation(string) || translate('en', 'ja', string)
    end

    def to_en(string)
      cached_en_tanslation(string) || translate('ja', 'en', string)
    end

    private

    def initialize_caches!
      @en = {} if @en.nil?
      @ja = {} if @ja.nil?
    end

    def cached_en_tanslation(string)
      initialize_caches!
      @en[Digest::SHA2.hexdigest(string)]
    end

    def cached_ja_tanslation(string)
      initialize_caches!
      @ja[Digest::SHA2.hexdigest(string)]
    end

    def translate(from, to, string)
      req = {
        text: string,
        source_language_code: from,
        target_language_code: to
      }

      client = Aws::Translate::Client.new(region: 'us-east-1')
      translated = client.translate_text(req).translated_text

      if to == 'ja'
        @ja[Digest::SHA2.hexdigest(string)] = translated
      else
        @en[Digest::SHA2.hexdigest(string)] = translated
      end

      translated
    end

  end
end