class RuboCop::Cop::Style::RedundantParentheses

def allowed_ancestor?(node)
  # Don't flag `break(1)`, etc
  keyword_ancestor?(node) && parens_required?(node)
end

def allowed_array_or_hash_element?(node)
  # Don't flag
  # ```
  # { a: (1
  #      ), }
  # ```
  (hash_element?(node) || array_element?(node)) &&
    only_closing_paren_before_comma?(node)
end

def allowed_expression?(node)
  allowed_ancestor?(node) ||
    allowed_method_call?(node) ||
    allowed_array_or_hash_element?(node) ||
    allowed_multiple_expression?(node)
end

def allowed_method_call?(node)
  # Don't flag `method (arg) { }`
  arg_in_call_with_block?(node) && !parentheses?(node.parent)
end

def allowed_multiple_expression?(node)
  return false if node.children.one?
  ancestor = node.ancestors.first
  return false unless ancestor
  !ancestor.begin_type? && !ancestor.def_type? && !ancestor.block_type?
end

def array_element?(node)
  node.parent && node.parent.array_type?
end

def autocorrect(node)
  ParenthesesCorrector.correct(node)
end

def call_chain_starts_with_int?(begin_node, send_node)
  recv = first_part_of_call_chain(send_node)
  recv && recv.int_type? && (parent = begin_node.parent) &&
    parent.send_type? && (parent.method?(:-@) || parent.method?(:+@))
end

def check(begin_node)
  node = begin_node.children.first
  if keyword_with_redundant_parentheses?(node)
    return offense(begin_node, 'a keyword')
  end
  if disallowed_literal?(begin_node, node)
    return offense(begin_node, 'a literal')
  end
  return offense(begin_node, 'a variable') if node.variable?
  return offense(begin_node, 'a constant') if node.const_type?
  check_send(begin_node, node) if node.send_type?
end

def check_send(begin_node, node)
  return check_unary(begin_node, node) if node.unary_operation?
  return unless method_call_with_redundant_parentheses?(node)
  return if call_chain_starts_with_int?(begin_node, node)
  offense(begin_node, 'a method call')
end

def check_unary(begin_node, node)
  return if begin_node.chained?
  node = node.children.first while suspect_unary?(node)
  if node.send_type?
    return unless method_call_with_redundant_parentheses?(node)
  end
  offense(begin_node, 'an unary operation')
end

def disallowed_literal?(begin_node, node)
  node.literal? &&
    !ALLOWED_LITERALS.include?(node.type) &&
    !raised_to_power_negative_numeric?(begin_node, node)
end

def empty_parentheses?(node)
  # Don't flag `()`
  node.children.empty?
end

def first_argument?(node)
  first_send_argument?(node) || first_super_argument?(node)
end

def hash_element?(node)
  node.parent && node.parent.pair_type?
end

def hash_literal_as_first_arg?(node)
  # Don't flag `method ({key: value})`
  node.children.first.hash_type? && first_argument?(node) &&
    !parentheses?(node.parent)
end

def keyword_ancestor?(node)
  node.parent && node.parent.keyword?
end

def keyword_with_redundant_parentheses?(node)
  return false unless node.keyword?
  return true if node.special_keyword?
  args = *node
  if only_begin_arg?(args)
    parentheses?(args.first)
  else
    args.empty? || parentheses?(node)
  end
end

def method_call_with_redundant_parentheses?(node)
  return false unless node.send_type?
  return false if node.prefix_not?
  return false if range_end?(node)
  send_node, args = method_node_and_args(node)
  args.empty? || parentheses?(send_node) || square_brackets?(send_node)
end

def offense(node, msg)
  add_offense(node, message: "Don't use parentheses around #{msg}.")
end

def on_begin(node)
  return if !parentheses?(node) || parens_allowed?(node)
  check(node)
end

def only_begin_arg?(args)
  args.one? && args.first.begin_type?
end

def only_closing_paren_before_comma?(node)
  source_buffer = node.source_range.source_buffer
  line_range = source_buffer.line_range(node.loc.end.line)
  line_range.source =~ /^\s*\)\s*,/
end

def parens_allowed?(node)
  empty_parentheses?(node) ||
    hash_literal_as_first_arg?(node) ||
    rescue?(node) ||
    allowed_expression?(node)
end

def raised_to_power_negative_numeric?(begin_node, node)
  return false unless node.numeric_type?
  siblings = begin_node.parent && begin_node.parent.children
  return false if siblings.nil?
  next_sibling = siblings[begin_node.sibling_index + 1]
  base_value = node.children.first
  base_value < 0 && next_sibling == :**
end

def suspect_unary?(node)
  node.send_type? && node.unary_operation? && !node.prefix_not?
end