class RuboCop::Cop::Sorbet::SignatureBuildOrder

def autocorrect(node)
  return nil unless can_autocorrect?
  lambda do |corrector|
    nodes = call_chain(node).sort_by { |call| ORDER[call.method_name] }
    tree =
      nodes.reduce(nil) do |receiver, caller|
        caller.updated(nil, [receiver] + caller.children.drop(1))
      end
    corrector.replace(
      node.source_range,
      Unparser.unparse(tree),
    )
  end
end

def call_chain(sig_child_node)
  call_node = root_call(sig_child_node).first
  return [] unless call_node
  calls = []
  while call_node != sig_child_node
    calls << call_node
    call_node = call_node.parent
  end
  calls << sig_child_node
  calls
end

def can_autocorrect?
  defined?(::Unparser)
end

def on_signature(node)
  calls = call_chain(node.children[2]).map(&:method_name)
  return unless calls.any?
  expected_order = calls.sort_by { |call| ORDER[call] }
  return if expected_order == calls
  message = "Sig builders must be invoked in the following order: #{expected_order.join(', ')}."
  unless can_autocorrect?
    message += ' For autocorrection, add the `unparser` gem to your project.'
  end
  add_offense(
    node.children[2],
    message: message,
  )
  node
end