class ActiveRecord::Associations::HasManyThroughAssociation < ActiveRecord::Associations::AssociationProxy

  def find_target
    records = @reflection.klass.find(:all,
      :select     => construct_select,
      :conditions => construct_conditions,
      :from       => construct_from,
      :joins      => construct_joins,
      :order      => @reflection.options[:order],
      :limit      => @reflection.options[:limit],
      :group      => @reflection.options[:group],
      :include    => @reflection.options[:include] || @reflection.source_reflection.options[:include]
    )
    @reflection.options[:uniq] ? records.to_set.to_a : records
  end


  def construct_joins(custom_joins = nil)
    reflection = @reflection
    joins = []
    while reflection.through_reflection
      joins << construct_one_join(reflection)
      reflection = reflection.through_reflection
    end
    "#{joins.join(' ')} #{custom_joins}"
  end

   def construct_one_join(reflection)
    polymorphic_join = nil
    if reflection.through_reflection.options[:as] || reflection.source_reflection.macro == :belongs_to
      reflection_primary_key = reflection.klass.primary_key
      source_primary_key     = reflection.source_reflection.primary_key_name
      if reflection.options[:source_type]
        polymorphic_join = "AND %s.%s = %s" % [
          reflection.through_reflection.table_name, "#{reflection.source_reflection.options[:foreign_type]}",
          @owner.class.quote_value(reflection.options[:source_type])
        ]
      end
    else
      reflection_primary_key = reflection.source_reflection.primary_key_name
      source_primary_key     = reflection.klass.primary_key
      if reflection.source_reflection.options[:as]
        polymorphic_join = "AND %s.%s = %s" % [
          reflection.table_name, "#{reflection.source_reflection.options[:as]}_type",
          @owner.class.quote_value(reflection.through_reflection.klass.name)
        ]
      end
    end

    "INNER JOIN %s ON %s.%s = %s.%s %s #{reflection.options[:joins]}" % [
      reflection.through_reflection.table_name,
      reflection.table_name, reflection_primary_key,
      reflection.through_reflection.table_name, source_primary_key,
      polymorphic_join
    ]
  end

  def last_through_reflection
    reflection = @reflection.through_reflection
    while reflection.through_reflection
      reflection = reflection.through_reflection
    end
    reflection
  end

  def construct_conditions
    table_name = last_through_reflection.table_name
    conditions = construct_quoted_owner_attributes(last_through_reflection).map do |attr, value|
      "#{table_name}.#{attr} = #{value}"
    end
    conditions << @reflection.source_reflection.options[:conditions] if @reflection.source_reflection.options[:conditions]
    conditions << sql_conditions if sql_conditions
    "(" + conditions.join(') AND (') + ")"
  end


  def one_condition(reflection)
    [
      conditions_of_reflection(reflection),
      ("#{reflection.table_name}.#{reflection.klass.inheritance_column} = #{reflection.klass.quote_value(reflection.klass.name.demodulize)}" unless reflection.klass.descends_from_active_record?),
      ("#{reflection.table_name}.#{reflection.klass.deleted_attribute} IS NULL" if reflection.klass.paranoid?)
    ]
  end

  def conditions_of_reflection(reflection)
    (interpolate_sql(reflection.klass.send(:sanitize_sql, reflection.options[:conditions])) if reflection.options[:conditions])
  end

  def conditions
    reflection = @reflection
    conditions = [conditions_of_reflection(reflection)]
    while reflection = reflection.through_reflection
      conditions += one_condition(reflection)
    end
    conditions.compact!
    @conditions ||= conditions.join(' AND ') unless conditions.empty?
  end
  alias_method :sql_conditions, :conditions

end