module RailsSlugs
  module ActiveRecord
    module Base

      def self.included(base)
        base.extend ClassMethods
      end

      def to_param
        self.class.sluggable? ? slug : super
      end

      protected

      def assign_slug
        if slug.nil? or not slug_changed?
          options = self.class.slug
          case options
          when Symbol      
            value = send(options)
          when Array                     
            value = options.each.map{|p|send(p)}.join(' ')
          when Proc                       
            value = options.call(self)
          end
          if value.present?
            value = value.parameterize
            previous_value = previous_slug?(value)
            if previous_value != false
              if previous_value.present?
                index = Regexp.new(value + '-(\d+)$').match(previous_value)
                if index.present?
                  value << "-#{index[1].to_i + 1}"
                else
                  value << '-1'
                end
              end
              self.slug = value
            end
          end
        end
      end

      module ClassMethods

        def inherited(subclass)
          subclass.instance_variable_set(:@slug, @slug)
          super
        end
        
        def sluggable?
          @slug.present?
        end
        
        def slug(*args)
          if args.any?
            unless sluggable?
              if respond_to? :translatable? and translatable?
                include RailsSlugs::ActiveRecord::Base::Translatable
                attr_translatable :slug 
                before_validation :generate_slugs
              else
                include RailsSlugs::ActiveRecord::Base::NonTranslatable
                before_validation :generate_slug
              end
              @slug = args.size == 1 ? args[0] : args                              
            end
          end
          @slug
        end
      
      end
      module NonTranslatable

        def self.included(base)
          base.extend ClassMethods
        end
        
        protected
        
        def previous_slug?(slug)
          r = self.class.where(
            "(slug = '#{slug}' OR slug LIKE '#{slug}-_')"
          ).order(
            'slug DESC'
          ).first
          r.respond_to?(:slug) ? (r == self ? false : r.slug) : nil
        end

        def generate_slug
          assign_slug
        end

        module ClassMethods

          def exists_by_slug(id)
            exists? :slug => id
          end
      
        end
      end
      module Translatable
      
        def self.included(base)
          base.extend ClassMethods
        end
        
        protected

        def change_locale(locale)
          I18n.locale = locale
          with_locale locale
        end

        def previous_slug?(slug)
          t = self.class.reflect_on_association(:translations)
          r = self.class.joins(
            "INNER JOIN #{t.table_name} t ON t.#{t.foreign_key} = #{self.class.table_name}.#{t.active_record_primary_key}"
          ).where(
            "(t.slug = '#{slug}' OR t.slug LIKE '#{slug}-_') AND t.locale = '#{I18n.locale.to_s}'"
          ).order(
            't.slug DESC'
          ).first
          r.respond_to?(:slug) ? (r == self ? false : r.slug) : nil
        end

        def generate_slugs
          locale = current_locale
          I18n.available_locales.each do |locale|
            change_locale locale
            assign_slug
          end
          change_locale locale
        end

        module ClassMethods

          def find_by_slug(id)
            t = reflect_on_association(:translations)
            joins(
              "INNER JOIN #{t.table_name} t ON t.#{t.foreign_key} = #{table_name}.#{t.active_record_primary_key}"
            ).where(
              "t.slug = '#{id}' AND t.locale = '#{I18n.locale.to_s}'"
            ).readonly(false).first
          end
          
          def exists_by_slug(id)
            t = reflect_on_association(:translations)
            joins(:translations).exists?(t.table_name.to_sym => {:slug => id, :locale => I18n.locale})
          end

        end      
      end
    end
  end
end