module ActiveRecord
  module Acts #:nodoc:
    module Taggable #:nodoc:
      def self.included(base)
        base.extend(ClassMethods)
      end

      module ClassMethods
        def acts_as_taggable(options = {})
          write_inheritable_attribute(:acts_as_taggable_options, {
            :taggable_type => ActiveRecord::Base.send(:class_name_of_active_record_descendant, self).to_s,
            :from => options[:from]
          })

          class_inheritable_reader :acts_as_taggable_options

          has_many :taggings, :as => :taggable, :dependent => true
          has_many :tags, :through => :taggings

          include ActiveRecord::Acts::Taggable::InstanceMethods
          extend ActiveRecord::Acts::Taggable::SingletonMethods
        end
      end

      module SingletonMethods
        def find_tagged_with(*list)
          find_by_sql([
            "SELECT #{table_name}.* FROM #{table_name}, tags, taggings " +
            "WHERE #{table_name}.#{primary_key} = taggings.taggable_id " +
            "AND taggings.taggable_type = ? " +
            "AND taggings.tag_id = tags.id AND tags.name IN (?)",
            acts_as_taggable_options[:taggable_type], list
          ]).uniq
        end

        def find_tagged_with_all (*list)
          tagged = list.collect { |name| find_tagged_with(name) }
          tagged.inject { |items, tagged| items & tagged }
        end

        def tags_with_count
          Tagging.count :conditions => ["taggable_type = ?", acts_as_taggable_options[:taggable_type]], :joins => "LEFT JOIN tags ON taggings.tag_id=tags.id", :group => 'tags.name', :order => 'tags.name'
        end
      end

      module InstanceMethods
        def tag_with(list)
          Tag.transaction do
            self.taggings.destroy_all

            Tag.parse(list).each do |name|
              if acts_as_taggable_options[:from]
                send(acts_as_taggable_options[:from]).tags.find_or_create_by_name(name).on(self)
              else
                Tag.find_or_create_by_name(name).on(self)
              end
            end
          end
        end

        def tag_list
          tags.collect { |tag| tag.name.include?(" ") ? "\"#{tag.name}\"" : tag.name }.join(" ")
        end
      end
    end
  end
end