class RuboCop::Cop::Sorbet::SignatureBuildOrder

def on_signature(node)
  body = node.body
  actual_calls_and_indexes = call_chain(body).map.with_index do |send_node, actual_index|
    # The index this method call appears at in the configured Order.
    expected_index = builder_method_indexes[send_node.method_name]
    [send_node, actual_index, expected_index]
  end
  # Temporarily extract unknown method calls
  expected_calls_and_indexes, unknown_calls_and_indexes = actual_calls_and_indexes
    .partition { |_, _, expected_index| expected_index }
  # Sort known method calls by expected index
  expected_calls_and_indexes.sort_by! { |_, _, expected_index| expected_index }
  # Re-insert unknown method calls in their positions
  unknown_calls_and_indexes.each do |entry|
    _, original_index, _ = entry
    expected_calls_and_indexes.insert(original_index, entry)
  end
  # Compare expected and actual ordering
  expected_method_names = expected_calls_and_indexes.map { |send_node, _, _| send_node.method_name }
  actual_method_names = actual_calls_and_indexes.map { |send_node, _, _| send_node.method_name }
  return if expected_method_names == actual_method_names
  add_offense(
    body,
    message: "Sig builders must be invoked in the following order: #{expected_method_names.join(", ")}.",
  ) { |corrector| corrector.replace(body, expected_source(expected_calls_and_indexes)) }
end