# TODO: add a check to make sure a relationship doens't already exist before insert

module ActiveRecord
  module Associations # :nodoc:

    module ClassMethods

      def has_many_polymorphs(association_id, options={})

        pjoin = options[:polymorphic_join_table]

        #from polymorphic column field names
        pfrom = {:id_label => (options[:polymorphic_from].to_s + '_id').to_sym,:type_label => (options[:polymorphic_from].to_s + '_type').to_sym, :type => self}

        #to polymorphic column field names
        pto = {:id_label => (options[:polymorphic_to].to_s + '_id').to_sym,:type_label => (options[:polymorphic_to].to_s + '_type').to_sym,:type => association_id.to_s.classify.to_s, :table => association_id}

        single_direction_finder = "SELECT #{pto[:table]}.* " +
          "FROM #{pto[:table]} INNER JOIN #{pjoin} ON #{pto[:table]}.id = #{pjoin}.#{pto[:id_label]} " +
          "WHERE #{pjoin}.#{pfrom[:id_label]} =" + ' #{id} ' +
          "AND #{pjoin}.#{pfrom[:type_label]} = '#{pfrom[:type]}' AND #{pjoin}.#{pto[:type_label]} = '#{pto[:type]}'"

        bidirectional_finder = "SELECT #{pto[:table]}.* " +
          "FROM #{pto[:table]} INNER JOIN #{pjoin} ON " +
            "(#{pto[:table]}.id = #{pjoin}.#{pto[:id_label]} AND #{pjoin}.#{pfrom[:type_label]} = '#{pfrom[:type]}') OR " +
            "(#{pto[:table]}.id = #{pjoin}.#{pfrom[:id_label]} AND #{pjoin}.#{pto[:type_label]} = '#{pfrom[:type]}') " +
          "WHERE " +
          "(#{pjoin}.#{pfrom[:id_label]} =" + ' #{id} ' + " AND #{pjoin}.#{pfrom[:type_label]} = '#{pfrom[:type]}' AND #{pjoin}.#{pto[:type_label]} = '#{pto[:type]}') " +
          "OR " +
          "(#{pjoin}.#{pto[:id_label]} =" + ' #{id} ' + " AND #{pjoin}.#{pto[:type_label]} = '#{pfrom[:type]}' AND #{pjoin}.#{pfrom[:type_label]} = '#{pto[:type]}') "

        class_eval do

          has_and_belongs_to_many pto[:table],
            {:join_table => pjoin,
             :foreign_key => pfrom[:id_label],
             :association_foreign_key => pto[:id_label],
             :finder_sql => (options[:bidirectional].blank? ? single_direction_finder : bidirectional_finder),
             :insert_sql =>
               "INSERT INTO #{pjoin} (`#{pfrom[:id_label]}`, `#{pfrom[:type_label]}`, `#{pto[:id_label]}`, `#{pto[:type_label]}`) " +
               'VALUES (#{id}, ' + "'#{pfrom[:type]}', " + '#{record.id}, ' + "'#{pto[:type]}')",
             :delete_sql =>
               "DELETE FROM #{pjoin} WHERE #{pfrom[:id_label]} = " +
               '#{id}' + " AND #{pfrom[:type_label]} = '#{pfrom[:type]}' AND #{pto[:id_label]} = " +
               '#{record.id}' + " AND #{pto[:type_label]} = '#{pto[:type]}'"
             }
      end #end clas_eval

      end #end def


  end #end classmethods
  end #associatioins

end #end active record