module ActsAsTaggableOn::Taggable
  module Ownership
    def self.included(base)
      base.extend ActsAsTaggableOn::Taggable::Ownership::ClassMethods

      base.class_eval do
        after_save :save_owned_tags
      end

      base.initialize_acts_as_taggable_on_ownership
    end

    module ClassMethods
      def acts_as_taggable_on(*args)
        initialize_acts_as_taggable_on_ownership
        super(*args)
      end

      def initialize_acts_as_taggable_on_ownership
        tag_types.map(&:to_s).each do |tag_type|
          class_eval <<-RUBY, __FILE__, __LINE__ + 1
            def #{tag_type}_from(owner)
              owner_tag_list_on(owner, '#{tag_type}')
            end
          RUBY
        end
      end
    end

    def owner_tags_on(owner, context)
      if owner.nil?
        scope = base_tags.where([%(#{ActsAsTaggableOn::Tagging.table_name}.context = ?), context.to_s])
      else
        scope = base_tags.where([%(#{ActsAsTaggableOn::Tagging.table_name}.context = ? AND
                                    #{ActsAsTaggableOn::Tagging.table_name}.tagger_id = ? AND
                                    #{ActsAsTaggableOn::Tagging.table_name}.tagger_type = ?), context.to_s, owner.id, owner.class.base_class.to_s])
      end

      # when preserving tag order, return tags in created order
      # if we added the order to the association this would always apply
      if self.class.preserve_tag_order?
        scope.order("#{ActsAsTaggableOn::Tagging.table_name}.id")
      else
        scope
      end
    end

    def cached_owned_tag_list_on(context)
      variable_name = "@owned_#{context}_list"
      (instance_variable_defined?(variable_name) && instance_variable_get(variable_name)) || instance_variable_set(variable_name, {})
    end

    def owner_tag_list_on(owner, context)
      add_custom_context(context)

      cache = cached_owned_tag_list_on(context)

      cache[owner] ||= ActsAsTaggableOn::TagList.new(*owner_tags_on(owner, context).map(&:name))
    end

    def set_owner_tag_list_on(owner, context, new_list)
      add_custom_context(context)

      cache = cached_owned_tag_list_on(context)

      cache[owner] = ActsAsTaggableOn::TagList.from(new_list)
    end

    def reload(*args)
      self.class.tag_types.each do |context|
        instance_variable_set("@owned_#{context}_list", nil)
      end

      super(*args)
    end

    def save_owned_tags
      tagging_contexts.each do |context|
        cached_owned_tag_list_on(context).each do |owner, tag_list|

          # Find existing tags or create non-existing tags:
          tags = ActsAsTaggableOn::Tag.find_or_create_all_with_like_by_name(tag_list.uniq)

          # Tag objects for owned tags
          owned_tags = owner_tags_on(owner, context)

          # Tag maintenance based on whether preserving the created order of tags
          if self.class.preserve_tag_order?
            old_tags, new_tags = owned_tags - tags, tags - owned_tags

            shared_tags = owned_tags & tags

            if shared_tags.any? && tags[0...shared_tags.size] != shared_tags
              index = shared_tags.each_with_index { |_, i| break i unless shared_tags[i] == tags[i] }

              # Update arrays of tag objects
              old_tags |= owned_tags.from(index)
              new_tags |= owned_tags.from(index) & shared_tags

              # Order the array of tag objects to match the tag list
              new_tags = tags.map { |t| new_tags.find { |n| n.name.downcase == t.name.downcase } }.compact
            end
          else
            # Delete discarded tags and create new tags
            old_tags = owned_tags - tags
            new_tags = tags - owned_tags
          end

          # Find all taggings that belong to the taggable (self), are owned by the owner,
          # have the correct context, and are removed from the list.
          if old_tags.present?
            old_taggings = ActsAsTaggableOn::Tagging.where(:taggable_id => id, :taggable_type => self.class.base_class.to_s,
                                                            :tagger_type => owner.class.base_class.to_s, :tagger_id => owner.id,
                                                            :tag_id => old_tags, :context => context)
          end

          # Destroy old taggings:
          if old_taggings.present?
            ActsAsTaggableOn::Tagging.destroy_all(:id => old_taggings.map(&:id))
          end

          # Create new taggings:
          new_tags.each do |tag|
            taggings.create!(:tag_id => tag.id, :context => context.to_s, :tagger => owner, :taggable => self)
          end
        end
      end

      true
    end
  end
end