create_table :friendships do |t|
  t.column :user_id,    :integer, :null => false
  t.column :friend_id,  :integer, :null => false
  t.column :status,     :integer, :null => false, :default => 0
  t.column :created_at, :datetime
end

class User < ActiveRecord::Base
  has_many :friendships_as_user,
        :foreign_key => 'user_id',
        :class_name => 'Friendship'

  has_many :friendships_as_friend,
        :foreign_key => 'friend_id',
        :class_name => 'Friendship'

  has_many :users,
        :through => :friendships_as_user,
        :source => :friend

  has_many :friends_from_me,
        :through => :friendships_as_user,
        :source => :user,
        :conditions => 'friendships.status = 1'

  has_many :friends_for_me,
        :through => :friendships_as_friend,
        :source => :friend,
        :conditions => 'friendships.status = 1'

  has_many :awaiting_friends_from_me,
        :through => :friendships_as_user,
        :source => :user,
        :conditions => 'friendships.status = 0'

  has_many :awaiting_friends_for_me,
        :through => :friendships_as_friend,
        :source => :friend,
        :conditions => 'friendships.status = 0'

  def friends
    self.friends_for_me + self.friends_from_me
  end

  def awaiting_friends
    self.awaiting_friends_for_me + self.awaiting_friends_from_me
  end
end

class Friendship < ActiveRecord::Base
  belongs_to :user,   :class_name => 'User', :foreign_key => :friend_id
  belongs_to :friend, :class_name => 'User', :foreign_key => :user_id
end