module ElasticAPM
  module Util
    # @api private
    module Inflector
      # rubocop:disable all
      # From https://github.com/rails/rails/blob/861b70e92f4a1fc0e465ffcf2ee62680519c8f6f/activesupport/lib/active_support/inflector/methods.rb#L249
      #
      # Tries to find a constant with the name specified in the argument string.
      #
      #   'Module'.constantize     # => Module
      #   'Test::Unit'.constantize # => Test::Unit
      #
      # The name is assumed to be the one of a top-level constant, no matter
      # whether it starts with "::" or not. No lexical context is taken into
      # account:
      #
      #   C = 'outside'
      #   module M
      #     C = 'inside'
      #     C               # => 'inside'
      #     'C'.constantize # => 'outside', same as ::C
      #   end
      #
      # NameError is raised when the name is not in CamelCase or the constant is
      # unknown.
      def self.constantize(camel_cased_word)
        names = camel_cased_word.split('::')

        # Trigger a built-in NameError exception including the ill-formed constant in the message.
        Object.const_get(camel_cased_word) if names.empty?

        # Remove the first blank element in case of '::ClassName' notation.
        names.shift if names.size > 1 && names.first.empty?

        names.inject(Object) do |constant, name|
          if constant == Object
            constant.const_get(name)
          else
            candidate = constant.const_get(name)
            next candidate if constant.const_defined?(name, false)
            next candidate unless Object.const_defined?(name)

            # Go down the ancestors to check if it is owned directly. The check
            # stops when we reach Object or the end of ancestors tree.
            constant = constant.ancestors.inject do |const, ancestor|
              break const    if ancestor == Object
              break ancestor if ancestor.const_defined?(name, false)
              const
            end

            # owner is in Object, so raise
            constant.const_get(name, false)
          end
        end
      end
      # rubocop:enable all
    end
  end
end