class CCK::KeysChecker

def self.compare(detected, expected)
  new(detected, expected).compare
end

def compare
  return [] if identical_keys?
  errors << "Detected extra keys in message #{message_name}: #{extra_keys}" if extra_keys.any?
  errors << "Missing keys in message #{message_name}: #{missing_keys}" if missing_keys.any?
  errors
rescue StandardError => e
  ["Unexpected error: #{e.message}"]
end

def detected_keys
  @detected_keys ||= ordered_uniq_hash_keys(detected)
end

def errors
  @errors ||= []
end

def expected_keys
  @expected_keys ||= ordered_uniq_hash_keys(expected)
end

def extra_keys
  (detected_keys - expected_keys).reject { |key| meta_message? && key == :ci }
end

def identical_keys?
  detected_keys == expected_keys
end

def initialize(detected, expected)
  @detected = detected
  @expected = expected
end

def message_name
  detected.class.name
end

def meta_message?
  detected.instance_of?(Cucumber::Messages::Meta)
end

def missing_keys
  (expected_keys - detected_keys).reject { |key| meta_message? && key == :ci }
end

def ordered_uniq_hash_keys(object)
  object.to_h(reject_nil_values: true).keys.sort
end