#
# For users with login '*test_user*', we don't want to store these documents in
# the main users db. This is because we create and destroy a lot of test
# users. This weirdness of using a different db for some users breaks a lot of
# things, such as associations. However, this is OK for now since we don't need
# those for running the frequent nagios tests.
#
# This module is included in user.rb. This will only work if it is included
# after designs are defined, otherwise, the design definition will overwrite
# find_by_login().
#

module TemporaryUser
  extend ActiveSupport::Concern
  include CouchRest::Model::DatabaseMethod

  USER_DB     = 'users'
  TMP_USER_DB = 'tmp_users'
  TMP_LOGIN   = 'test_user'

  included do
    use_database_method :db_name

    # since the original find_by_login is dynamically created with
    # instance_eval, it appears that we also need to use instance eval to
    # override it.
    instance_eval <<-EOS, __FILE__, __LINE__ + 1
      def find_by_login(*args)
        if args.grep(/#{TMP_LOGIN}/).any?
          by_login.database(tmp_database).key(*args).first()
        else
          by_login.key(*args).first()
        end
      end
    EOS
  end

  module ClassMethods
    def get(id, db = database)
      super(id, db) || super(id, tmp_database)
    end
    alias :find :get

    # calls db_name(TMP_LOGIN), then creates a CouchRest::Database
    # from the name
    def tmp_database
      choose_database(TMP_LOGIN)
    end

    def db_name(login=nil)
      if !login.nil? && login.include?(TMP_LOGIN)
        TMP_USER_DB
      else
        USER_DB
      end
    end

    # create the tmp db if it doesn't exist.
    # requires admin access.
    def create_tmp_database!
      design_doc.sync!(tmp_database.tap{|db|db.create!})
    end
  end

  #
  # this gets called each and every time a User object needs to
  # access the database.
  #
  def db_name
    self.class.db_name(self.login)
  end

  # returns true if this User instance is stored in tmp db.
  def tmp?
    !login.nil? && login.include?(TMP_LOGIN)
  end

end