# All plugins should include this module. It defines the basic
# operations that all plugins are supposed to support.
module Plugin

  module Run
    # Module methods, meant to be extended. Includers can explicitly
    # extend this to get a run() method defined in terms of their own
    # runner() and dummy_runner() methods.

    def included(c)
      # Callback, called whenever another class or module includes this
      # one. The parameter given is the name of the class or module
      # that included us.
      @includers ||= []
      @includers << c
    end

    def includers
      @includers ||= []
      return @includers
    end

    def runner()
      # The Runner associated with this plugin.
      raise NotImplementedError
    end

    def dummy_runner()
      # The RummyRunner associated with this plugin.
      raise NotImplementedError
    end

    def run(cfg, *args)
      includers().each do |includer|
        plugin = includer.new(cfg)

        if cfg.i_mean_business then
          runner = runner().new()
        else
          runner = dummy_runner().new()
        end

        # The splat passes the correct (we hope) number of arguments to the
        # appropriate runner. The Rm(Dummy)Runner have splats on their
        # *target arguments as well, to turn ARGV back into an array.
        runner.run(plugin, *args)
      end
    end
  end

  def describe_domain(domain)
    # Provide a "description" of the domain. This is output along
    # with the domain name and can be anything of use to the system
    # administrator.
    raise NotImplementedError
  end

  def describe_user(user)
    # Provide a "description" of the user. This is output along
    # with the domain name and can be anything of use to the system
    # administrator.
    raise NotImplementedError
  end

  def list_users()
    # Return a list of all users managed by this plugin.
    raise NotImplementedError
  end

  def user_exists(username)
    # Does the given username exist for this plugin? We use a naive
    # implementation here based on list_users() which is required to
    # exist above. Plugins can override this with something fast.
    users = list_users()
    return users.include?(username)
  end

  def list_domains_users(domains)
    # Get all usernames belonging to the given domains. If a username
    # ends in @example.com, it belongs to the domain example.com
    #
    # This uses a naive loop, but relies only on the existence of a
    # list_users() method which is guaranteed above. More efficient
    # implementations can usually be made within the plugin.
    domains_users = []

    usernames = list_users();
    domains.each do |d|
      matches = usernames.select do |username|
        username =~ /@#{d}$/
      end

      domains_users += matches
    end

    return domains_users
  end

end