Find delegated methods in Ruby on Rails

delegated = delegates(project, :ci_cd_settings)

def delegates(fromobj, tosym)
  # Get map of delegated methods.

  # Rails doesn't maintain a table of delegated methods, so it needs to be
  # reconstructed by parsing methods source.
  regex = /^\s*delegate .*to: \s*:#{tosym}.*/mx

  delegated = {}
  fromobj.methods.each do |symname|
    method = fromobj.method(symname)
    next unless method.source_location

    next unless method.source =~ regex

    name = symname.to_s
    # Example for `Project.last.method("ci_opt_in_jwt").source``
    # "  delegate :opt_in_jwt, :opt_in_jwt=, to: :ci_cd_settings, prefix: :ci, allow_nil: true\n"
    prefix_match = method.source.match /prefix: \s+ :(\w+)/mx
    delegated[name] =
      if prefix_match
        name.delete_prefix("#{prefix_match[1]}_")
      else
        name
      end
  end
  delegated
end