multilingualism support for jekyll

multilingualism.rb

# example
# .
# |-- about.md
# |-- _config.yml
# |-- css
# |   `-- main.css
# |-- feed.xml
# |-- .gitignore
# |-- _includes
# |   |-- footer.html
# |   |-- header.html
# |   `-- head.html
# |-- index.html
# |-- _layouts
# |   |-- default.html
# |   |-- page.html
# |   `-- post.html
# |-- _plugins
# |   `-- multilingualism.rb
# |-- _posts
# |   |-- 2014-05-12-hello-world.en.md
# |   |-- 2014-05-12-hello-world.ja.md
# |   `-- 2014-05-13-hello-world.md
# `-- _site
#     |-- about
#     |   `-- index.html
#     |-- css
#     |   `-- main.css
#     |-- en
#     |   `-- 2014
#     |       `-- 05
#     |           `-- 12
#     |               `-- hello-world
#     |                   `-- index.html
#     |-- feed.xml
#     |-- index.html
#     `-- ja
#         `-- 2014
#             `-- 05
#                 `-- 12
#                     `-- hello-world
#                         `-- index.html
# 
# 18 directories, 22 files

# require 'jekyll/mpultiple/languages/plugin'

module Jekyll

  class Site

    attr_accessor :i18n

    alias :process_orig :process
    def process()

      i18n_config = "#{self.source}/_i18n.yml"

      if File.exists? i18n_config
        @i18n = YAML.load(File.read(i18n_config))
        p @i18n
      else
        Jekyll.logger.warn "Your site lacks a _i18n.yml config, it's required for multilingualism plugin."
      end

      process_orig
    end
  end

  class Post

    LANG_MATCHER = /^(.+\/)*(\d+-\d+-\d+)-(.*?)(\.[\w]{2})?(\.[^.]+)$/

    attr_accessor :lang

    alias :process_orig :process
    def process(name)
      m, cats, date, slug, lang, ext = *name.match(LANG_MATCHER)

      self.date = Time.parse(date)
      self.slug = slug
      self.ext = ext
      self.lang = (lang && lang.gsub('.', '')) || site.config['languages'].first
    rescue ArgumentError
      path = File.join(@dir || "", name)
      msg  =  "Post '#{path}' does not have a valid date.\n"
      msg  << "Fix the date, or exclude the file or directory from being processed"
      raise FatalException.new(msg)
    end

    def path_in_lang(lang)
      path.gsub(".#{@lang}", "").gsub("#{ext}", "") + ".#{lang}" + ext
    end

    def path_without_lang
      path.gsub(".#{@lang}", "")
    end

    def in_language?(lang)
      return true if lang == self.lang
      return true if File.exists? path_in_lang(lang)
      (lang == site.config['languages'].first) && (File.exists? path_without_lang)
    end

    def template
      case site.permalink_style
      when :pretty
        "/:lang/:categories/:year/:month/:day/:title/"
      when :none
        "/:lang/:categories/:title.html"
      when :date
        "/:lang/:categories/:year/:month/:day/:title.html"
      when :ordinal
        "/:lang/:categories/:year/:y_day/:title.html"
      else
        site.permalink_style.to_s
      end
    end

    def url_placeholders
      {
        :year        => date.strftime("%Y"),
        :month       => date.strftime("%m"),
        :day         => date.strftime("%d"),
        :title       => slug,
        :i_day       => date.strftime("%d").to_i.to_s,
        :i_month     => date.strftime("%m").to_i.to_s,
        :categories  => (categories || []).map { |c| c.to_s }.join('/'),
        :short_month => date.strftime("%b"),
        :short_year  => date.strftime("%y"),
        :y_day       => date.strftime("%j"),
        :output_ext  => output_ext,
        :lang        => @lang
      }
    end

  end

  class Page


    LANG_MATCHER = /^(.*?)(\.[\w]{2})?(\.[^.]+)$/

    attr_accessor :lang

    alias :process_orig :process
    def process(name)
      m, basename, lang, ext = *name.match(LANG_MATCHER)

      self.basename = basename
      self.lang = (lang && lang.gsub('.', '')) || site.config['languages'].first
      self.ext = ext
    end

    def path_in_lang(lang)
      path.gsub(".#{@lang}", "").gsub("#{ext}", "") + ".#{lang}" + ext
    end

    def path_without_lang
      path.gsub(".#{@lang}", "")
    end

    def in_language?(lang)
      File.exists? path_in_lang(lang)
      return true if lang == self.lang
      return true if File.exists? path_in_lang(lang)
      (lang == site.config['languages'].first) && (File.exists? path_without_lang)
    end

    def template
      if site.permalink_style == :pretty
        if index? && html?
          "/:path/"
        elsif html?
          "/:lang/:path/:basename/"
        elsif excluded?
          "/:path/:basename:output_ext"
        else
          "/:lang/:path/:basename:output_ext"
        end
      else
        "/:lang/:path/:basename:output_ext"
      end
    end

    def url_placeholders
      {
        :path       => @dir,
        :basename   => basename,
        :output_ext => output_ext,
        :lang       => lang
      }
    end

    def excluded?
      site.config['multilingual_exclude'].include? name
    end

  end

  module Convertible

    def write(dest)
      path = destination(dest)
      FileUtils.mkdir_p(File.dirname(path))
      File.open(path, 'wb') do |f|
        f.write(output)
      end
    end

  end

  class LocalizeTag < Liquid::Tag

    def initialize(tag_name, params, tokens)
      super
      @key, @lang = params.strip.split(' ')
    end

    def render(context)
      lang = @lang || context.registers[:site].config['languages'].first
      if (context.registers[:site].i18n.include? @key) &&
          (context.registers[:site].i18n[@key].include? lang)
        context.registers[:site].i18n[@key][lang]
      else
        raise KeyError.new "I found no key: #{@key} in #{lang} defined in _i18n.yml"
      end
    end

  end

end

Liquid::Template.register_tag('t', Jekyll::LocalizeTag)

With multilingual plugin, posts/pages should be named in yyyy-mm-dd-foo-bar.#{lang}.ext form, which #{lang} is the ISO 639 codes. Posts/pages which lack a #{lang} part is considered as in default language.

use in_language?(lang) method to check if the post is in the corresponding language (useful when show link in templates).