def matching_contexts_for(search_context, result_context, klass, options = {})
tags_to_find = tags_on(search_context).collect { |t| t.name }
exclude_self = "#{klass.table_name}.#{klass.primary_key} != #{id} AND" if [self.class.base_class, self.class].include? klass
group_columns = ActsAsTaggableOn::Tag.using_postgresql? ? grouped_column_names_for(klass) : "#{klass.table_name}.#{klass.primary_key}"
klass.scoped({ :select => "#{klass.table_name}.*, COUNT(#{ActsAsTaggableOn::Tag.table_name}.#{ActsAsTaggableOn::Tag.primary_key}) AS count",
:from => "#{klass.table_name}, #{ActsAsTaggableOn::Tag.table_name}, #{ActsAsTaggableOn::Tagging.table_name}",
:conditions => ["#{exclude_self} #{klass.table_name}.#{klass.primary_key} = #{ActsAsTaggableOn::Tagging.table_name}.taggable_id AND #{ActsAsTaggableOn::Tagging.table_name}.taggable_type = '#{klass.base_class.to_s}' AND #{ActsAsTaggableOn::Tagging.table_name}.tag_id = #{ActsAsTaggableOn::Tag.table_name}.#{ActsAsTaggableOn::Tag.primary_key} AND #{ActsAsTaggableOn::Tag.table_name}.name IN (?) AND #{ActsAsTaggableOn::Tagging.table_name}.context = ?", tags_to_find, result_context],
:group => group_columns,
:order => "count DESC" }.update(options))
end