class RuboCop::Cop::Style::BlockDelimiters

def array_or_range?(node)
  node.array_type? || node.range_type?
end

def autocorrect(corrector, node)
  return if correction_would_break_code?(node)
  if node.braces?
    replace_braces_with_do_end(corrector, node.loc)
  else
    replace_do_end_with_braces(corrector, node)
  end
end

def begin_required?(block_node)
  # If the block contains `rescue` or `ensure`, it needs to be wrapped in
  # `begin`...`end` when changing `do-end` to `{}`.
  block_node.each_child_node(:rescue, :ensure).any? && !block_node.single_line?
end

def braces_for_chaining_message(node)
  if node.multiline?
    if node.chained?
      'Prefer `{...}` over `do...end` for multi-line chained blocks.'
    else
      'Prefer `do...end` for multi-line blocks without chaining.'
    end
  else
    'Prefer `{...}` over `do...end` for single-line blocks.'
  end
end

def braces_for_chaining_style?(node)
  block_begin = node.loc.begin.source
  block_begin == if node.multiline?
                   (node.chained? ? '{' : 'do')
                 else
                   '{'
                 end
end

def braces_required_message(node)
  format(BRACES_REQUIRED_MESSAGE, method_name: node.method_name.to_s)
end

def braces_required_method?(method_name)
  braces_required_methods.include?(method_name.to_s)
end

def braces_required_methods
  cop_config.fetch('BracesRequiredMethods', [])
end

def braces_style?(node)
  node.loc.begin.source == '{'
end

def conditional?(node)
  node.if_type? || node.or_type? || node.and_type?
end

def correction_would_break_code?(node)
  return unless node.keywords?
  node.send_node.arguments? && !node.send_node.parenthesized?
end

def end_of_chain(node)
  return end_of_chain(node.block_node) if with_block?(node)
  return node unless node.chained?
  end_of_chain(node.parent)
end

def functional_block?(node)
  return_value_used?(node) || return_value_of_scope?(node)
end

def functional_method?(method_name)
  cop_config['FunctionalMethods'].map(&:to_sym).include?(method_name)
end

def get_blocks(node, &block)
  case node.type
  when :block, :numblock
    yield node
  when :send
    get_blocks(node.receiver, &block) if node.receiver
  when :hash
    # A hash which is passed as method argument may have no braces
    # In that case, one of the K/V pairs could contain a block node
    # which could change in meaning if do...end replaced {...}
    return if node.braces?
    node.each_child_node { |child| get_blocks(child, &block) }
  when :pair
    node.each_child_node { |child| get_blocks(child, &block) }
  end
end

def line_count_based_block_style?(node)
  node.multiline? ^ node.braces?
end

def line_count_based_message(node)
  if node.multiline?
    'Avoid using `{...}` for multi-line blocks.'
  else
    'Prefer `{...}` over `do...end` for single-line blocks.'
  end
end

def message(node)
  return braces_required_message(node) if braces_required_method?(node.method_name)
  case style
  when :line_count_based    then line_count_based_message(node)
  when :semantic            then semantic_message(node)
  when :braces_for_chaining then braces_for_chaining_message(node)
  when :always_braces       then ALWAYS_BRACES_MESSAGE
  end
end

def move_comment_before_block(corrector, comment, block_node, closing_brace)
  range = block_node.chained? ? end_of_chain(block_node.parent).source_range : closing_brace
  corrector.remove(range_with_surrounding_space(comment.source_range, side: :right))
  remove_trailing_whitespace(corrector, range, comment)
  corrector.insert_after(range, "\n")
  corrector.insert_before(block_node, "#{comment.text}\n")
end

def on_block(node)
  return if ignored_node?(node)
  return if proper_block_style?(node)
  message = message(node)
  add_offense(node.loc.begin, message: message) do |corrector|
    autocorrect(corrector, node)
  end
end

def on_send(node)
  return unless node.arguments?
  return if node.parenthesized?
  return if node.operator_method? || node.assignment_method?
  node.arguments.each do |arg|
    get_blocks(arg) do |block|
      # If there are no parentheses around the arguments, then braces
      # and do-end have different meaning due to how they bind, so we
      # allow either.
      ignore_node(block)
    end
  end
end

def procedural_method?(method_name)
  cop_config['ProceduralMethods'].map(&:to_sym).include?(method_name)
end

def procedural_oneliners_may_have_braces?
  cop_config['AllowBracesOnProceduralOneLiners']
end

def proper_block_style?(node)
  return true if require_braces?(node)
  return special_method_proper_block_style?(node) if special_method?(node.method_name)
  case style
  when :line_count_based    then line_count_based_block_style?(node)
  when :semantic            then semantic_block_style?(node)
  when :braces_for_chaining then braces_for_chaining_style?(node)
  when :always_braces       then braces_style?(node)
  end
end

def remove_trailing_whitespace(corrector, range, comment)
  range_of_trailing = range.end.join(comment.source_range.begin)
  corrector.remove(range_of_trailing) if range_of_trailing.source.match?(/\A\s+\z/)
end

def replace_braces_with_do_end(corrector, loc)
  b = loc.begin
  e = loc.end
  corrector.insert_before(b, ' ') unless whitespace_before?(b)
  corrector.insert_before(e, ' ') unless whitespace_before?(e)
  corrector.insert_after(b, ' ') unless whitespace_after?(b)
  corrector.replace(b, 'do')
  if (comment = processed_source.comment_at_line(e.line))
    move_comment_before_block(corrector, comment, loc.node, e)
  end
  corrector.replace(e, 'end')
end

def replace_do_end_with_braces(corrector, node)
  loc = node.loc
  b = loc.begin
  e = loc.end
  corrector.insert_after(b, ' ') unless whitespace_after?(b, 2)
  corrector.replace(b, '{')
  corrector.replace(e, '}')
  corrector.wrap(node.body, "begin\n", "\nend") if begin_required?(node)
end

def require_braces?(node)
  return false unless node.braces?
  node.each_ancestor(:send).any? do |send|
    send.arithmetic_operation? && node.source_range.end_pos < send.loc.selector.begin_pos
  end
end

def return_value_of_scope?(node)
  return unless node.parent
  conditional?(node.parent) || array_or_range?(node.parent) ||
    node.parent.children.last == node
end

def return_value_used?(node)
  return unless node.parent
  # If there are parentheses around the block, check if that
  # is being used.
  if node.parent.begin_type?
    return_value_used?(node.parent)
  else
    node.parent.assignment? || node.parent.call_type?
  end
end

def semantic_block_style?(node)
  method_name = node.method_name
  if node.braces?
    functional_method?(method_name) || functional_block?(node) ||
      (procedural_oneliners_may_have_braces? && !node.multiline?)
  else
    procedural_method?(method_name) || !return_value_used?(node)
  end
end

def semantic_message(node)
  block_begin = node.loc.begin.source
  if block_begin == '{'
    'Prefer `do...end` over `{...}` for procedural blocks.'
  else
    'Prefer `{...}` over `do...end` for functional blocks.'
  end
end

def special_method?(method_name)
  allowed_method?(method_name) ||
    matches_allowed_pattern?(method_name) ||
    braces_required_method?(method_name)
end

def special_method_proper_block_style?(node)
  method_name = node.method_name
  return true if allowed_method?(method_name) || matches_allowed_pattern?(method_name)
  return node.braces? if braces_required_method?(method_name)
end

def whitespace_after?(range, length = 1)
  /\s/.match?(range.source_buffer.source[range.begin_pos + length, 1])
end

def whitespace_before?(range)
  /\s/.match?(range.source_buffer.source[range.begin_pos - 1, 1])
end

def with_block?(node)
  node.respond_to?(:block_node) && node.block_node
end