class RuboCop::ConfigObsoletion

def initialize(config)
  @config = config
  @rules = load_rules
  @warnings = []
end

def legacy_cop_names
  # Used by DepartmentName#qualified_legacy_cop_name
  new(Config.new).rules.select(&:cop_rule?).map(&:old_name)
end

def load_cop_rules(rules)
  rules.flat_map do |rule_type, data|
    data.map do |cop_name, configuration|
      next unless configuration # allow configurations to be disabled with `CopName: ~`
      COP_RULE_CLASSES[rule_type].new(@config, cop_name, configuration)
    end.compact
  end
end

def load_parameter_rules(rules)
  rules.flat_map do |rule_type, data|
    data.flat_map do |configuration|
      cops = Array(configuration['cops'])
      parameters = Array(configuration['parameters'])
      cops.product(parameters).map do |cop, parameter|
        PARAMETER_RULE_CLASSES[rule_type].new(@config, cop, parameter, configuration)
      end
    end
  end
end

def load_rules
  rules = self.class.files.each_with_object({}) do |filename, hash|
    hash.merge!(YAML.safe_load(File.read(filename))) do |_key, first, second|
      first.merge(second)
    end
  end
  cop_rules = rules.slice(*COP_RULE_CLASSES.keys)
  parameter_rules = rules.slice(*PARAMETER_RULE_CLASSES.keys)
  load_cop_rules(cop_rules).concat(load_parameter_rules(parameter_rules))
end

def obsoletions
  rules.map do |rule|
    next unless rule.violated?
    if rule.warning?
      @warnings.push(rule.message)
      next
    end
    rule.message
  end
end

def reject_obsolete!
  messages = obsoletions.flatten.compact
  return if messages.empty?
  raise ValidationError, messages.join("\n")
end