Use i18n-tasks for YAML files update

Remove the old code of the solidus_i18n:sync task and document the use of
i18n-tasks.

README.md

@@ -57,6 +57,20 @@ you want your users to be able to select from the locale toggle on the frontend.
 
 ---
 
+## Updating Translations
+
+If you want to improve the translations on your language, run the tasks:
+
+    bundle exec rake solidus_i18n:update_default
+    bundle exec i18n-tasks add-missing --nil-value --locale <LOCALE>
+
+Substitute <LOCALE> with your locale code (e.g: `it`).
+
+This will do a cleanup and prepare `<LOCALE>.yml` with all the missing keys.
+You can then write the translations and open a pull request.
+
+---
+
 ## Model Translations
 
 We **removed** support for translating models into [a separate Gem](https://github.com/solidusio-contrib/solidus_globalize).

Rakefile

@@ -32,32 +32,7 @@ namespace :solidus_i18n do
     end
   end
 
-  desc 'Syncronize translation files with latest en (adds comments with fallback en value)'
-  task :sync do
-    puts 'Starting syncronization...'
-    words = translation_keys
-
-    Dir["#{locales_dir}/*.yml"].each do |filename|
-      basename = File.basename(filename, '.yml')
-      (comments, other) = SolidusI18n::Utils.read_file(filename, basename)
-      # Initializing hash variable as en fallback if it does not exist
-      words.each { |k, _v| other[k] ||= "#{words[k]}" }
-      # Remove if not defined in en locale
-      other.delete_if { |k, _v| !words[k] }
-      SolidusI18n::Utils.write_file(filename, basename, comments, other, false)
-    end
-  end
-
-  def translation_keys
-    (dummy_comments, words) = SolidusI18n::Utils.read_file(File.dirname(__FILE__) + '/default/solidus_core.yml', 'en')
-      words
-  end
-
   def locales_dir
     File.join File.dirname(__FILE__), 'config/locales'
   end
-
-  def env_locale
-    ENV['LOCALE'].presence
-  end
 end

lib/solidus_i18n.rb

@@ -3,6 +3,5 @@
 require 'solidus_i18n/engine'
 require 'solidus_i18n/locale'
 require 'solidus_i18n/version'
-require 'solidus_i18n/utils'
 require 'coffee_script'
 require 'deface'